[core] Rewrite image handling

* Consolidate Image and StillImage
* Typecheck unassociated vs premultiplied images
* Rewrite default platform image decoding implementation

34 files changed, 307 insertions, 696 deletions

diff --git a/bin/render.cpp b/bin/render.cpp
index 685f3ddac4..8a8bcc1a4b 100644
--- a/bin/render.cpp
+++ b/bin/render.cpp
@@ -1,5 +1,4 @@
 #include <mbgl/map/map.hpp>
-#include <mbgl/map/still_image.hpp>
 #include <mbgl/util/image.hpp>
 #include <mbgl/util/io.hpp>
 
@@ -105,16 +104,14 @@ int main(int argc, char *argv[]) {
 
     uv_async_t *async = new uv_async_t;
     uv_async_init(uv_default_loop(), async, [](UV_ASYNC_PARAMS(as)) {
-        std::unique_ptr<const StillImage> image(reinterpret_cast<const StillImage *>(as->data));
+        std::unique_ptr<UnassociatedImage> image(reinterpret_cast<UnassociatedImage*>(as->data));
         uv_close(reinterpret_cast<uv_handle_t *>(as), [](uv_handle_t *handle) {
             delete reinterpret_cast<uv_async_t *>(handle);
         });
-
-        const std::string png = util::compress_png(image->width, image->height, image->pixels.get());
-        util::write_file(output, png);
+        util::write_file(output, encodePNG(*image));
     });
 
-    map.renderStill([async](std::exception_ptr error, std::unique_ptr<const StillImage> image) {
+    map.renderStill([async](std::exception_ptr error, UnassociatedImage&& image) {
         try {
             if (error) {
                 std::rethrow_exception(error);
@@ -124,7 +121,7 @@ int main(int argc, char *argv[]) {
             exit(1);
         }
 
-        async->data = const_cast<StillImage *>(image.release());
+        async->data = new UnassociatedImage(std::move(image));
         uv_async_send(async);
     });
 
diff --git a/gyp/platform-android.gypi b/gyp/platform-android.gypi
index c12c7d2600..e3e1141c51 100644
--- a/gyp/platform-android.gypi
+++ b/gyp/platform-android.gypi
@@ -15,7 +15,6 @@
         '../platform/default/thread.cpp',
         '../platform/default/string_stdlib.cpp',
         '../platform/default/image.cpp',
-        '../platform/default/image_reader.cpp',
         '../platform/default/png_reader.cpp',
         '../platform/default/jpeg_reader.cpp',
       ],
diff --git a/gyp/platform-linux.gypi b/gyp/platform-linux.gypi
index f614b831e5..3ee39e2b70 100644
--- a/gyp/platform-linux.gypi
+++ b/gyp/platform-linux.gypi
@@ -16,7 +16,6 @@
         '../platform/default/asset_root.cpp',
         '../platform/default/thread.cpp',
         '../platform/default/image.cpp',
-        '../platform/default/image_reader.cpp',
         '../platform/default/png_reader.cpp',
         '../platform/default/jpeg_reader.cpp',
       ],
diff --git a/include/mbgl/map/map.hpp b/include/mbgl/map/map.hpp
index c190088088..80b50c2fa4 100644
--- a/include/mbgl/map/map.hpp
+++ b/include/mbgl/map/map.hpp
@@ -2,6 +2,7 @@
 #define MBGL_MAP_MAP
 
 #include <mbgl/util/chrono.hpp>
+#include <mbgl/util/image.hpp>
 #include <mbgl/map/update.hpp>
 #include <mbgl/map/mode.hpp>
 #include <mbgl/util/geo.hpp>
@@ -21,7 +22,6 @@ class FileSource;
 class View;
 class MapData;
 class MapContext;
-class StillImage;
 class SpriteImage;
 class Transform;
 class PointAnnotation;
@@ -58,7 +58,7 @@ public:
 
     // Register a callback that will get called (on the render thread) when all resources have
     // been loaded and a complete render occurs.
-    using StillImageCallback = std::function<void(std::exception_ptr, std::unique_ptr<const StillImage>)>;
+    using StillImageCallback = std::function<void (std::exception_ptr, UnassociatedImage&&)>;
     void renderStill(StillImageCallback callback);
 
     // Triggers a synchronous render.
diff --git a/include/mbgl/map/still_image.hpp b/include/mbgl/map/still_image.hpp
deleted file mode 100644
index 36922fe95a..0000000000
--- a/include/mbgl/map/still_image.hpp
+++ /dev/null
@@ -1,19 +0,0 @@
-#ifndef MBGL_MAP_STILL_IMAGE
-#define MBGL_MAP_STILL_IMAGE
-
-#include <mbgl/util/noncopyable.hpp>
-
-#include <cstdint>
-
-namespace mbgl {
-
-class StillImage : util::noncopyable {
-public:
-    size_t width = 0;
-    size_t height = 0;
-    std::unique_ptr<uint8_t[]> pixels;
-};
-
-}
-
-#endif
diff --git a/include/mbgl/map/view.hpp b/include/mbgl/map/view.hpp
index fadd035e49..68bde5fe30 100644
--- a/include/mbgl/map/view.hpp
+++ b/include/mbgl/map/view.hpp
@@ -2,14 +2,14 @@
 #define MBGL_MAP_VIEW
 
 #include <mbgl/util/chrono.hpp>
-#include <functional>
+#include <mbgl/util/image.hpp>
 
+#include <functional>
 #include <memory>
 
 namespace mbgl {
 
 class Map;
-class StillImage;
 
 enum MapChange : uint8_t {
     MapChangeRegionWillChange = 0,
@@ -70,7 +70,7 @@ public:
 
     // Reads the pixel data from the current framebuffer. If your View implementation
     // doesn't support reading from the framebuffer, return a null pointer.
-    virtual std::unique_ptr<StillImage> readStillImage();
+    virtual UnassociatedImage readStillImage();
 
     // Notifies a watcher of map x/y/scale/rotation changes.
     // Must only be called from the same thread that caused the change.
diff --git a/include/mbgl/platform/default/headless_view.hpp b/include/mbgl/platform/default/headless_view.hpp
index 50edc48428..8b25620524 100644
--- a/include/mbgl/platform/default/headless_view.hpp
+++ b/include/mbgl/platform/default/headless_view.hpp
@@ -39,7 +39,7 @@ public:
     void invalidate() override;
     void beforeRender() override;
     void afterRender() override;
-    std::unique_ptr<StillImage> readStillImage() override;
+    UnassociatedImage readStillImage() override;
 
     void resizeFramebuffer();
     void resize(uint16_t width, uint16_t height);
diff --git a/include/mbgl/platform/default/image_reader.hpp b/include/mbgl/platform/default/image_reader.hpp
deleted file mode 100644
index e46bb08ea2..0000000000
--- a/include/mbgl/platform/default/image_reader.hpp
+++ /dev/null
@@ -1,40 +0,0 @@
-#ifndef MBGL_UTIL_IMAGE_READER_HPP
-#define MBGL_UTIL_IMAGE_READER_HPP
-
-#include <mbgl/util/noncopyable.hpp>
-// stl
-#include <stdexcept>
-#include <string>
-#include <memory>
-
-namespace mbgl { namespace util {
-
-class ImageReaderException : public std::exception
-{
-private:
-    std::string message_;
-public:
-    ImageReaderException(std::string const& message)
-        : message_(message) {}
-
-    ~ImageReaderException() throw() {}
-
-    virtual const char* what() const throw()
-    {
-        return message_.c_str();
-    }
-};
-
-struct ImageReader : private noncopyable
-{
-    virtual unsigned width() const=0;
-    virtual unsigned height() const=0;
-    virtual std::unique_ptr<uint8_t[]> read()=0;
-    virtual ~ImageReader() {}
-};
-
-std::unique_ptr<ImageReader> getImageReader(const uint8_t* data, size_t size);
-
-}}
-
-#endif
diff --git a/include/mbgl/platform/default/jpeg_reader.hpp b/include/mbgl/platform/default/jpeg_reader.hpp
deleted file mode 100644
index 2f988374c3..0000000000
--- a/include/mbgl/platform/default/jpeg_reader.hpp
+++ /dev/null
@@ -1,72 +0,0 @@
-#ifndef MBGL_UTIL_JPEG_READER_HPP
-#define MBGL_UTIL_JPEG_READER_HPP
-
-#include <mbgl/platform/default/image_reader.hpp>
-
-// jpeg
-extern "C"
-{
-#include <jpeglib.h>
-}
-
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wunknown-pragmas"
-#pragma GCC diagnostic ignored "-Wunused-local-typedefs"
-#pragma GCC diagnostic ignored "-Wshadow"
-#include <boost/iostreams/stream.hpp>
-#pragma GCC diagnostic pop
-
-namespace mbgl { namespace util {
-
-template <typename T>
-class JpegReader : public ImageReader
-{
-public:
-    using source_type = T;
-    using input_stream = boost::iostreams::stream<source_type>;
-    const static unsigned BUF_SIZE = 4096;
-private:
-    struct jpeg_stream_wrapper
-    {
-        jpeg_source_mgr manager;
-        input_stream * stream;
-        JOCTET buffer[BUF_SIZE];
-    };
-
-    struct jpeg_info_guard
-    {
-        jpeg_info_guard(jpeg_decompress_struct * cinfo)
-            : i_(cinfo) {}
-
-        ~jpeg_info_guard()
-        {
-            jpeg_destroy_decompress(i_);
-        }
-        jpeg_decompress_struct * i_;
-    };
-
-private:
-    source_type source_;
-    input_stream stream_;
-    unsigned width_;
-    unsigned height_;
-public:
-    JpegReader(const uint8_t* data, size_t size);
-    ~JpegReader();
-    unsigned width() const;
-    unsigned height() const;
-    std::unique_ptr<uint8_t[]> read();
-private:
-    void init();
-    static void on_error(j_common_ptr cinfo);
-    static void on_error_message(j_common_ptr cinfo);
-    static void init_source(j_decompress_ptr cinfo);
-    static boolean fill_input_buffer(j_decompress_ptr cinfo);
-    static void skip(j_decompress_ptr cinfo, long count);
-    static void term(j_decompress_ptr cinfo);
-    static void attach_stream(j_decompress_ptr cinfo, input_stream* in);
-};
-
-}}
-
-#endif // MBGL_UTIL_JPEG_READER_HPP
diff --git a/include/mbgl/platform/default/png_reader.hpp b/include/mbgl/platform/default/png_reader.hpp
deleted file mode 100644
index c869e78ea4..0000000000
--- a/include/mbgl/platform/default/png_reader.hpp
+++ /dev/null
@@ -1,65 +0,0 @@
-#ifndef MBGL_UTIL_PNG_READER_HPP
-#define MBGL_UTIL_PNG_READER_HPP
-
-#include <mbgl/platform/default/image_reader.hpp>
-
-extern "C"
-{
-#include <png.h>
-}
-
-#include <cstring>
-#include <memory>
-
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wunknown-pragmas"
-#pragma GCC diagnostic ignored "-Wunused-local-typedefs"
-#pragma GCC diagnostic ignored "-Wshadow"
-#include <boost/iostreams/stream.hpp>
-#pragma GCC diagnostic pop
-
-namespace mbgl { namespace util {
-
-template <typename T>
-class PngReader : public ImageReader
-{
-    using source_type = T;
-    using input_stream = boost::iostreams::stream<source_type>;
-
-    struct png_struct_guard
-    {
-        png_struct_guard(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr)
-            : p_(png_ptr_ptr),
-              i_(info_ptr_ptr) {}
-
-        ~png_struct_guard()
-        {
-            png_destroy_read_struct(p_,i_,0);
-        }
-        png_structpp p_;
-        png_infopp i_;
-    };
-
-private:
-    source_type source_;
-    input_stream stream_;
-    unsigned width_;
-    unsigned height_;
-    int bit_depth_;
-    int color_type_;
-    bool has_alpha_;
-public:
-    PngReader(const uint8_t* data, std::size_t size);
-    ~PngReader();
-    unsigned width() const;
-    unsigned height() const;
-    std::unique_ptr<uint8_t[]> read();
-private:
-    void init();
-    static void png_read_data(png_structp png_ptr, png_bytep data, png_size_t length);
-};
-
-
-}}
-
-#endif // MBGL_UTIL_PNG_READER_HPP
diff --git a/include/mbgl/util/image.hpp b/include/mbgl/util/image.hpp
index fc4078501e..0604691dd1 100644
--- a/include/mbgl/util/image.hpp
+++ b/include/mbgl/util/image.hpp
@@ -5,30 +5,37 @@
 #include <memory>
 
 namespace mbgl {
-namespace util {
-
-std::string compress_png(size_t width, size_t height, const uint8_t* rgba);
 
+enum ImageAlphaMode {
+    Unassociated,
+    Premultiplied
+};
 
+template <ImageAlphaMode Mode>
 class Image {
 public:
-    explicit Image(const std::string& img);
+    Image() {}
 
-    inline const uint8_t* getData() const { return img.get(); }
-    inline uint32_t getWidth() const { return width; }
-    inline uint32_t getHeight() const { return height; }
-    inline operator bool() const { return img && width && height; }
+    Image(size_t w, size_t h)
+        : width(w),
+          height(h),
+          data(std::make_unique<uint8_t[]>(size())) {}
 
-private:
-    // loaded image dimensions
-    uint32_t width = 0, height = 0;
+    size_t stride() const { return width * 4; }
+    size_t size() const { return width * height * 4; }
 
-    // the raw image data
-    std::unique_ptr<uint8_t[]> img;
+    size_t width = 0;
+    size_t height = 0;
+    std::unique_ptr<uint8_t[]> data;
 };
 
+using UnassociatedImage = Image<ImageAlphaMode::Unassociated>;
+using PremultipliedImage = Image<ImageAlphaMode::Premultiplied>;
+
+// TODO: don't use std::string for binary data.
+PremultipliedImage decodeImage(const std::string&);
+std::string encodePNG(const UnassociatedImage&);
 
-}
 }
 
 #endif
diff --git a/platform/darwin/image.mm b/platform/darwin/image.mm
index 8965f1ea93..e7187366b9 100644
--- a/platform/darwin/image.mm
+++ b/platform/darwin/image.mm
@@ -9,10 +9,9 @@
 #endif
 
 namespace mbgl {
-namespace util {
 
-std::string compress_png(size_t width, size_t height, const uint8_t* rgba) {
-    CGDataProviderRef provider = CGDataProviderCreateWithData(NULL, rgba, width * height * 4, NULL);
+std::string encodePNG(const UnassociatedImage& src) {
+    CGDataProviderRef provider = CGDataProviderCreateWithData(NULL, src.data.get(), src.size(), NULL);
     if (!provider) {
         return "";
     }
@@ -23,7 +22,7 @@ std::string compress_png(size_t width, size_t height, const uint8_t* rgba) {
         return "";
     }
 
-    CGImageRef image = CGImageCreate(width, height, 8, 32, 4 * width, color_space,
+    CGImageRef image = CGImageCreate(src.width, src.height, 8, 32, 4 * src.width, color_space,
         kCGBitmapByteOrderDefault | kCGImageAlphaLast, provider, NULL, false,
         kCGRenderingIntentDefault);
     if (!image) {
@@ -66,23 +65,23 @@ std::string compress_png(size_t width, size_t height, const uint8_t* rgba) {
     return result;
 }
 
-Image::Image(const std::string &source_data) {
+PremultipliedImage decodeImage(const std::string &source_data) {
     CFDataRef data = CFDataCreateWithBytesNoCopy(kCFAllocatorDefault, reinterpret_cast<const unsigned char *>(source_data.data()), source_data.size(), kCFAllocatorNull);
     if (!data) {
-        return;
+        throw std::runtime_error("CFDataCreateWithBytesNoCopy failed");
     }
 
     CGImageSourceRef image_source = CGImageSourceCreateWithData(data, NULL);
     if (!image_source) {
         CFRelease(data);
-        return;
+        throw std::runtime_error("CGImageSourceCreateWithData failed");
     }
 
     CGImageRef image = CGImageSourceCreateImageAtIndex(image_source, 0, NULL);
     if (!image) {
         CFRelease(image_source);
         CFRelease(data);
-        return;
+        throw std::runtime_error("CGImageSourceCreateImageAtIndex failed");
     }
 
     CGColorSpaceRef color_space = CGColorSpaceCreateDeviceRGB();
@@ -90,27 +89,24 @@ Image::Image(const std::string &source_data) {
         CGImageRelease(image);
         CFRelease(image_source);
         CFRelease(data);
-        return;
+        throw std::runtime_error("CGColorSpaceCreateDeviceRGB failed");
     }
 
-    width = uint32_t(CGImageGetWidth(image));
-    height = uint32_t(CGImageGetHeight(image));
-    CGRect rect = {{ 0, 0 }, { static_cast<CGFloat>(width), static_cast<CGFloat>(height) }};
+    PremultipliedImage result { CGImageGetWidth(image), CGImageGetHeight(image) };
 
-    img = std::make_unique<uint8_t[]>(width * height * 4);
-    CGContextRef context = CGBitmapContextCreate(img.get(), width, height, 8, width * 4,
+    CGContextRef context = CGBitmapContextCreate(result.data.get(), result.width, result.height, 8, result.stride(),
         color_space, kCGImageAlphaPremultipliedLast);
     if (!context) {
         CGColorSpaceRelease(color_space);
         CGImageRelease(image);
         CFRelease(image_source);
         CFRelease(data);
-        width = 0;
-        height = 0;
-        return;
+        throw std::runtime_error("CGBitmapContextCreate failed");
     }
 
     CGContextSetBlendMode(context, kCGBlendModeCopy);
+
+    CGRect rect = {{ 0, 0 }, { static_cast<CGFloat>(result.width), static_cast<CGFloat>(result.height) }};
     CGContextDrawImage(context, rect, image);
 
     CGContextRelease(context);
@@ -118,7 +114,8 @@ Image::Image(const std::string &source_data) {
     CGImageRelease(image);
     CFRelease(image_source);
     CFRelease(data);
+
+    return result;
 }
 
 }
-}
\ No newline at end of file
diff --git a/platform/default/headless_view.cpp b/platform/default/headless_view.cpp
index fa83f65967..d96b3ffcd1 100644
--- a/platform/default/headless_view.cpp
+++ b/platform/default/headless_view.cpp
@@ -3,9 +3,6 @@
 #include <mbgl/platform/default/headless_display.hpp>
 #include <mbgl/platform/log.hpp>
 
-#include <mbgl/map/still_image.hpp>
-
-
 #include <stdexcept>
 #include <sstream>
 #include <string>
@@ -170,29 +167,25 @@ void HeadlessView::resize(const uint16_t width, const uint16_t height) {
     needsResize = true;
 }
 
-std::unique_ptr<StillImage> HeadlessView::readStillImage() {
+UnassociatedImage HeadlessView::readStillImage() {
     assert(isActive());
 
     const unsigned int w = dimensions[0] * pixelRatio;
     const unsigned int h = dimensions[1] * pixelRatio;
 
-    auto image = std::make_unique<StillImage>();
-    image->width = w;
-    image->height = h;
-    image->pixels = std::make_unique<uint8_t[]>(w * h * 4);
-
-    MBGL_CHECK_ERROR(glReadPixels(0, 0, w, h, GL_RGBA, GL_UNSIGNED_BYTE, image->pixels.get()));
+    UnassociatedImage image { w, h };
+    MBGL_CHECK_ERROR(glReadPixels(0, 0, w, h, GL_RGBA, GL_UNSIGNED_BYTE, image.data.get()));
 
-    const int stride = w * 4;
-    auto tmp = std::make_unique<char[]>(stride);
-    char *rgba = reinterpret_cast<char *>(image->pixels.get());
+    const int stride = image.stride();
+    auto tmp = std::make_unique<uint8_t[]>(stride);
+    uint8_t* rgba = image.data.get();
     for (int i = 0, j = h - 1; i < j; i++, j--) {
         std::memcpy(tmp.get(), rgba + i * stride, stride);
         std::memcpy(rgba + i * stride, rgba + j * stride, stride);
         std::memcpy(rgba + j * stride, tmp.get(), stride);
     }
 
-    return image;
+    return std::move(image);
 }
 
 void HeadlessView::clearBuffers() {
diff --git a/platform/default/image.cpp b/platform/default/image.cpp
index 182b7d4c01..dc28c68ef9 100644
--- a/platform/default/image.cpp
+++ b/platform/default/image.cpp
@@ -1,16 +1,8 @@
 #include <mbgl/util/image.hpp>
-#include <mbgl/platform/log.hpp>
 #include <mbgl/util/string.hpp>
 
 #include <png.h>
 
-#include <cassert>
-#include <cstdlib>
-#include <stdexcept>
-#include <cstring>
-
-#include <mbgl/platform/default/image_reader.hpp>
-
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wunused-variable"
 // Check png library version.
@@ -25,32 +17,28 @@ const static bool png_version_check = []() {
     return true;
 }();
 #pragma GCC diagnostic pop
-
 namespace mbgl {
-namespace util {
 
-std::string compress_png(size_t width, size_t height, const uint8_t* rgba) {
+std::string encodePNG(const UnassociatedImage& src) {
     png_voidp error_ptr = 0;
     png_structp png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, error_ptr, NULL, NULL);
     if (!png_ptr) {
-        Log::Error(Event::Image, "couldn't create png_ptr");
-        return "";
+        throw std::runtime_error("couldn't create png_ptr");
     }
 
     png_infop info_ptr = png_create_info_struct(png_ptr);
     if (!png_ptr) {
         png_destroy_write_struct(&png_ptr, (png_infopp)0);
-        Log::Error(Event::Image, "couldn't create info_ptr");
-        return "";
+        throw std::runtime_error("couldn't create info_ptr");
     }
 
-    png_set_IHDR(png_ptr, info_ptr, width, height, 8, PNG_COLOR_TYPE_RGB_ALPHA, PNG_INTERLACE_NONE,
+    png_set_IHDR(png_ptr, info_ptr, src.width, src.height, 8, PNG_COLOR_TYPE_RGB_ALPHA, PNG_INTERLACE_NONE,
                  PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
 
     jmp_buf *jmp_context = (jmp_buf *)png_get_error_ptr(png_ptr);
     if (jmp_context) {
         png_destroy_write_struct(&png_ptr, &info_ptr);
-        return "";
+        throw std::runtime_error("png error");
     }
 
     std::string result;
@@ -63,10 +51,10 @@ std::string compress_png(size_t width, size_t height, const uint8_t* rgba) {
         ptrs(size_t count) : rows(new png_bytep[count]) {}
         ~ptrs() { delete[] rows; }
         png_bytep *rows = nullptr;
-    } pointers(height);
+    } pointers(src.height);
 
-    for (size_t i = 0; i < height; i++) {
-        pointers.rows[i] = (png_bytep)((png_bytep)rgba + width * 4 * i);
+    for (size_t i = 0; i < src.height; i++) {
+        pointers.rows[i] = src.data.get() + src.stride() * i;
     }
 
     png_set_rows(png_ptr, info_ptr, pointers.rows);
@@ -76,31 +64,28 @@ std::string compress_png(size_t width, size_t height, const uint8_t* rgba) {
     return result;
 }
 
-Image::Image(std::string const& data)
-{
-    try
-    {
-        auto reader = getImageReader(reinterpret_cast<const uint8_t*>(data.c_str()), data.size());
-        width = reader->width();
-        height = reader->height();
-        img = reader->read();
-    }
-    catch (ImageReaderException const& ex)
-    {
-        Log::Error(Event::Image, "%s", ex.what());
-        img.reset();
-        width = 0;
-        height = 0;
+PremultipliedImage decodePNG(const uint8_t*, size_t);
+PremultipliedImage decodeJPEG(const uint8_t*, size_t);
 
+PremultipliedImage decodeImage(const std::string& string) {
+    const uint8_t* data = reinterpret_cast<const uint8_t*>(string.data());
+    const size_t size = string.size();
+
+    if (size >= 4) {
+        unsigned int magic = (data[0] << 24) | (data[1] << 16) | (data[2] << 8) | data[3];
+        if (magic == 0x89504E47U) {
+            return decodePNG(data, size);
+        }
     }
-    catch (...) // catch the rest
-    {
-        Log::Error(Event::Image, "exception in constructor");
-        img.reset();
-        width = 0;
-        height = 0;
+
+    if (size >= 2) {
+        unsigned int magic = ((data[0] << 8) | data[1]) & 0xffff;
+        if (magic == 0xffd8) {
+            return decodeJPEG(data, size);
+        }
     }
-}
 
+    throw std::runtime_error("unsupported image type");
 }
+
 }
diff --git a/platform/default/image_reader.cpp b/platform/default/image_reader.cpp
deleted file mode 100644
index 3d27db58c3..0000000000
--- a/platform/default/image_reader.cpp
+++ /dev/null
@@ -1,62 +0,0 @@
-#include <mbgl/platform/default/image_reader.hpp>
-#include <mbgl/platform/default/png_reader.hpp>
-#include <mbgl/platform/default/jpeg_reader.hpp>
-
-#include <boost/optional.hpp>
-#include <boost/iostreams/device/array.hpp>
-
-namespace mbgl { namespace util {
-
-inline boost::optional<std::string> type_from_bytes(const uint8_t* data, size_t size)
-{
-    using result_type = boost::optional<std::string>;
-    if (size >= 4)
-    {
-        unsigned int magic = (data[0] << 24) | (data[1] << 16) | (data[2] << 8) | data[3];
-        if (magic == 0x89504E47U)
-        {
-            return result_type("png");
-        }
-        else if (magic == 0x49492A00 || magic == 0x4D4D002A)
-        {
-            return result_type("tiff");
-        }
-    }
-    if (size>=2)
-    {
-        unsigned int magic = ((data[0] << 8) | data[1]) & 0xffff;
-        if (magic == 0xffd8)
-        {
-            return result_type("jpeg");
-        }
-    }
-
-    if (size>=12)
-    {
-        if (data[0] == 'R' && data[1] == 'I' && data[2] == 'F' && data[3] == 'F' &&
-            data[8] == 'W' && data[9] == 'E' && data[10] == 'B' && data[11] == 'P')
-        {
-            return result_type("webp");
-        }
-    }
-    return result_type();
-}
-
-std::unique_ptr<ImageReader> getImageReader(const uint8_t* data, size_t size)
-{
-    boost::optional<std::string> type = type_from_bytes(data, size);
-    if (type)
-    {
-        if (*type == "png")
-        {
-            return std::make_unique<PngReader<boost::iostreams::array_source>>(data, size);
-        }
-        else if (*type == "jpeg")
-        {
-            return std::make_unique<JpegReader<boost::iostreams::array_source>>(data, size);
-        }
-    }
-    throw ImageReaderException("ImageReader: can't determine type from input data");
-}
-
-}}
diff --git a/platform/default/jpeg_reader.cpp b/platform/default/jpeg_reader.cpp
index a537eeeb08..73b0b9c1b2 100644
--- a/platform/default/jpeg_reader.cpp
+++ b/platform/default/jpeg_reader.cpp
@@ -1,43 +1,39 @@
-#include <mbgl/platform/default/jpeg_reader.hpp>
+#include <mbgl/util/image.hpp>
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunknown-pragmas"
+#pragma GCC diagnostic ignored "-Wunused-local-typedefs"
+#pragma GCC diagnostic ignored "-Wshadow"
+#include <boost/iostreams/stream.hpp>
+#pragma GCC diagnostic pop
 
-// boost
 #include <boost/iostreams/device/file.hpp>
 #include <boost/iostreams/device/array.hpp>
 
+extern "C"
+{
+#include <jpeglib.h>
+}
 
-// std
-#include <cstdio>
-#include <memory>
+namespace mbgl {
 
-namespace mbgl { namespace util {
+using source_type = boost::iostreams::array_source;
+using input_stream = boost::iostreams::stream<source_type>;
 
-// ctor
-template <typename T>
-JpegReader<T>::JpegReader(const uint8_t* data, size_t size)
-    : source_(reinterpret_cast<const char*>(data), size),
-      stream_(source_),
-      width_(0),
-      height_(0)
-{
-    if (!stream_) throw ImageReaderException("cannot open image stream");
-    init();
-}
+const static unsigned BUF_SIZE = 4096;
 
-// dtor
-template <typename T>
-JpegReader<T>::~JpegReader() {}
+struct jpeg_stream_wrapper {
+    jpeg_source_mgr manager;
+    input_stream * stream;
+    JOCTET buffer[BUF_SIZE];
+};
 
-// jpeg stream wrapper
-template <typename T>
-void JpegReader<T>::init_source (j_decompress_ptr cinfo)
-{
+static void init_source(j_decompress_ptr cinfo) {
     jpeg_stream_wrapper* wrap = reinterpret_cast<jpeg_stream_wrapper*>(cinfo->src);
     wrap->stream->seekg(0,std::ios_base::beg);
 }
 
-template <typename T>
-boolean JpegReader<T>::fill_input_buffer (j_decompress_ptr cinfo)
-{
+static boolean fill_input_buffer(j_decompress_ptr cinfo) {
     jpeg_stream_wrapper* wrap = reinterpret_cast<jpeg_stream_wrapper*>(cinfo->src);
     wrap->stream->read(reinterpret_cast<char*>(&wrap->buffer[0]),BUF_SIZE);
     std::streamsize size = wrap->stream->gcount();
@@ -46,9 +42,7 @@ boolean JpegReader<T>::fill_input_buffer (j_decompress_ptr cinfo)
     return (size > 0) ? TRUE : FALSE;
 }
 
-template <typename T>
-void JpegReader<T>::skip(j_decompress_ptr cinfo, long count)
-{
+static void skip(j_decompress_ptr cinfo, long count) {
     if (count <= 0) return; //A zero or negative skip count should be treated as a no-op.
     jpeg_stream_wrapper* wrap = reinterpret_cast<jpeg_stream_wrapper*>(cinfo->src);
 
@@ -66,21 +60,14 @@ void JpegReader<T>::skip(j_decompress_ptr cinfo, long count)
     }
 }
 
-template <typename T>
-void JpegReader<T>::term (j_decompress_ptr /*cinfo*/)
-{
-// no-op
-}
+static void term(j_decompress_ptr) {}
 
-template <typename T>
-void JpegReader<T>::attach_stream (j_decompress_ptr cinfo, input_stream* in)
-{
-    if (cinfo->src == 0)
-    {
+static void attach_stream(j_decompress_ptr cinfo, input_stream* in) {
+    if (cinfo->src == 0) {
         cinfo->src = (struct jpeg_source_mgr *)
             (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT, sizeof(jpeg_stream_wrapper));
     }
-    JpegReader::jpeg_stream_wrapper * src = reinterpret_cast<JpegReader::jpeg_stream_wrapper*> (cinfo->src);
+    jpeg_stream_wrapper * src = reinterpret_cast<jpeg_stream_wrapper*> (cinfo->src);
     src->manager.init_source = init_source;
     src->manager.fill_input_buffer = fill_input_buffer;
     src->manager.skip_input_data = skip;
@@ -91,22 +78,29 @@ void JpegReader<T>::attach_stream (j_decompress_ptr cinfo, input_stream* in)
     src->stream = in;
 }
 
-template <typename T>
-void JpegReader<T>::on_error(j_common_ptr /*cinfo*/)
-{
-}
+static void on_error(j_common_ptr) {}
 
-template <typename T>
-void JpegReader<T>::on_error_message(j_common_ptr cinfo)
-{
+static void on_error_message(j_common_ptr cinfo) {
     char buffer[JMSG_LENGTH_MAX];
     (*cinfo->err->format_message)(cinfo, buffer);
-    throw ImageReaderException(std::string("JPEG Reader: libjpeg could not read image: ") + buffer);
+    throw std::runtime_error(std::string("JPEG Reader: libjpeg could not read image: ") + buffer);
 }
 
-template <typename T>
-void JpegReader<T>::init()
-{
+struct jpeg_info_guard {
+    jpeg_info_guard(jpeg_decompress_struct* cinfo)
+        : i_(cinfo) {}
+
+    ~jpeg_info_guard() {
+        jpeg_destroy_decompress(i_);
+    }
+
+    jpeg_decompress_struct* i_;
+};
+
+PremultipliedImage decodeJPEG(const uint8_t* data, size_t size) {
+    source_type source(reinterpret_cast<const char*>(data), size);
+    input_stream stream(source);
+
     jpeg_decompress_struct cinfo;
     jpeg_info_guard iguard(&cinfo);
     jpeg_error_mgr jerr;
@@ -114,91 +108,52 @@ void JpegReader<T>::init()
     jerr.error_exit = on_error;
     jerr.output_message = on_error_message;
     jpeg_create_decompress(&cinfo);
-    attach_stream(&cinfo, &stream_);
+    attach_stream(&cinfo, &stream);
+
     int ret = jpeg_read_header(&cinfo, TRUE);
     if (ret != JPEG_HEADER_OK)
-        throw ImageReaderException("JPEG Reader: failed to read header");
+        throw std::runtime_error("JPEG Reader: failed to read header");
+
     jpeg_start_decompress(&cinfo);
-    width_ = cinfo.output_width;
-    height_ = cinfo.output_height;
 
     if (cinfo.out_color_space == JCS_UNKNOWN)
-    {
-        throw ImageReaderException("JPEG Reader: failed to read unknown color space");
-    }
-    if (cinfo.output_width == 0 || cinfo.output_height == 0)
-    {
-        throw ImageReaderException("JPEG Reader: failed to read image size of");
-    }
-}
+        throw std::runtime_error("JPEG Reader: failed to read unknown color space");
 
-template <typename T>
-unsigned JpegReader<T>::width() const
-{
-    return width_;
-}
+    if (cinfo.output_width == 0 || cinfo.output_height == 0)
+        throw std::runtime_error("JPEG Reader: failed to read image size");
 
-template <typename T>
-unsigned JpegReader<T>::height() const
-{
-    return height_;
-}
+    size_t width = cinfo.output_width;
+    size_t height = cinfo.output_height;
+    size_t components = cinfo.output_components;
+    size_t rowStride = components * width;
 
-template <typename T>
-std::unique_ptr<uint8_t[]> JpegReader<T>::read()
-{
-    std::unique_ptr<uint8_t[]> image = std::make_unique<uint8_t[]>(width_ * height_ * 4);
+    PremultipliedImage image { width, height };
+    uint8_t* dst = image.data.get();
 
-    stream_.clear();
-    stream_.seekg(0, std::ios_base::beg);
+    JSAMPARRAY buffer = (*cinfo.mem->alloc_sarray)((j_common_ptr) &cinfo, JPOOL_IMAGE, rowStride, 1);
 
-    jpeg_decompress_struct cinfo;
-    jpeg_info_guard iguard(&cinfo);
-    jpeg_error_mgr jerr;
-    cinfo.err = jpeg_std_error(&jerr);
-    jerr.error_exit = on_error;
-    jerr.output_message = on_error_message;
-    jpeg_create_decompress(&cinfo);
-    attach_stream(&cinfo, &stream_);
-    int ret = jpeg_read_header(&cinfo, TRUE);
-    if (ret != JPEG_HEADER_OK) throw ImageReaderException("JPEG Reader read(): failed to read header");
-    jpeg_start_decompress(&cinfo);
-    JSAMPARRAY buffer;
-    int row_stride;
-    unsigned char r,g,b;
-    row_stride = cinfo.output_width * cinfo.output_components;
-    buffer = (*cinfo.mem->alloc_sarray) ((j_common_ptr) &cinfo, JPOOL_IMAGE, row_stride, 1);
-
-    const std::unique_ptr<unsigned int[]> out_row(new unsigned int[width_]);
-    unsigned row = 0;
-    while (cinfo.output_scanline < cinfo.output_height)
-    {
+    while (cinfo.output_scanline < cinfo.output_height) {
         jpeg_read_scanlines(&cinfo, buffer, 1);
-        if (row < height_)
-        {
-            for (unsigned int x = 0; x < width_; ++x)
-            {
-                unsigned col = x;
-                r = buffer[0][cinfo.output_components * col];
-                if (cinfo.output_components > 2)
-                {
-                    g = buffer[0][cinfo.output_components * col + 1];
-                    b = buffer[0][cinfo.output_components * col + 2];
-                } else {
-                    g = r;
-                    b = r;
-                }
-                out_row[x] =  (0xff << 24) | (b << 16) | (g << 8) | r;
+
+        for (size_t i = 0; i < width; ++i) {
+            dst[0] = buffer[0][components * i];
+            dst[3] = 0xFF;
+
+            if (components > 2) {
+                dst[1] = buffer[0][components * i + 1];
+                dst[2] = buffer[0][components * i + 2];
+            } else {
+                dst[1] = dst[0];
+                dst[2] = dst[0];
             }
-            std::copy((char*)out_row.get(), (char*)out_row.get() + width_*4, image.get() + row*width_*4);
+
+            dst += 4;
         }
-        ++row;
     }
+
     jpeg_finish_decompress(&cinfo);
 
-    return image;
+    return std::move(image);
 }
 
-template class JpegReader<boost::iostreams::array_source>;
-
-}}
+}
diff --git a/platform/default/png_reader.cpp b/platform/default/png_reader.cpp
index 1f7207337c..7577d9725c 100644
--- a/platform/default/png_reader.cpp
+++ b/platform/default/png_reader.cpp
@@ -1,35 +1,35 @@
-#include <mbgl/platform/default/png_reader.hpp>
+#include <mbgl/util/image.hpp>
 #include <mbgl/platform/log.hpp>
-#include <iostream>
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunknown-pragmas"
+#pragma GCC diagnostic ignored "-Wunused-local-typedefs"
+#pragma GCC diagnostic ignored "-Wshadow"
+#include <boost/iostreams/stream.hpp>
+#pragma GCC diagnostic pop
+
+#include <boost/iostreams/device/file.hpp>
+#include <boost/iostreams/device/array.hpp>
+
 extern "C"
 {
 #include <png.h>
 }
 
-// boost
-#include <boost/iostreams/device/file.hpp>
-#include <boost/iostreams/device/array.hpp>
-#include <boost/iostreams/stream.hpp>
-
-// stl
-#include <cstring>
-#include <memory>
+namespace mbgl {
 
-namespace mbgl { namespace util {
+using source_type = boost::iostreams::array_source;
+using input_stream = boost::iostreams::stream<source_type>;
 
-void user_error_fn(png_structp /*png_ptr*/, png_const_charp error_msg)
-{
-    throw ImageReaderException(std::string("failed to read invalid png: '") + error_msg + "'");
+static void user_error_fn(png_structp, png_const_charp error_msg) {
+    throw std::runtime_error(std::string("failed to read invalid png: '") + error_msg + "'");
 }
 
-void user_warning_fn(png_structp /*png_ptr*/, png_const_charp warning_msg)
-{
+static void user_warning_fn(png_structp, png_const_charp warning_msg) {
     Log::Warning(Event::Image, "ImageReader (PNG): %s", warning_msg);
 }
 
-template <typename T>
-void PngReader<T>::png_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
-{
+static void png_read_data(png_structp png_ptr, png_bytep data, png_size_t length) {
     input_stream * fin = reinterpret_cast<input_stream*>(png_get_io_ptr(png_ptr));
     fin->read(reinterpret_cast<char*>(data), length);
     std::streamsize read_count = fin->gcount();
@@ -39,122 +39,74 @@ void PngReader<T>::png_read_data(png_structp png_ptr, png_bytep data, png_size_t
     }
 }
 
-template <typename T>
-PngReader<T>::PngReader(const uint8_t* data, std::size_t size)
-    : source_(reinterpret_cast<const char*>(data), size),
-      stream_(source_),
-      width_(0),
-      height_(0),
-      bit_depth_(0),
-      color_type_(0),
-      has_alpha_(false)
-{
+struct png_struct_guard {
+    png_struct_guard(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr)
+        : p_(png_ptr_ptr),
+          i_(info_ptr_ptr) {}
 
-    if (!stream_) throw ImageReaderException("PNG reader: cannot open image stream");
-    init();
-}
+    ~png_struct_guard() {
+        png_destroy_read_struct(p_,i_,0);
+    }
 
+    png_structpp p_;
+    png_infopp i_;
+};
 
-template <typename T>
-PngReader<T>::~PngReader() {}
+PremultipliedImage decodePNG(const uint8_t* data, size_t size) {
+    source_type source(reinterpret_cast<const char*>(data), size);
+    input_stream stream(source);
 
+    png_byte header[8] = { 0 };
+    stream.read(reinterpret_cast<char*>(header), 8);
+    if (stream.gcount() != 8)
+        throw std::runtime_error("PNG reader: Could not read image");
 
-template <typename T>
-void PngReader<T>::init()
-{
-    png_byte header[8];
-    std::memset(header,0,8);
-    stream_.read(reinterpret_cast<char*>(header),8);
-    if ( stream_.gcount() != 8)
-    {
-        throw ImageReaderException("PNG reader: Could not read image");
-    }
-    int is_png=!png_sig_cmp(header,0,8);
+    int is_png = !png_sig_cmp(header, 0, 8);
     if (!is_png)
-    {
-        throw ImageReaderException("File or stream is not a png");
-    }
-    png_structp png_ptr = png_create_read_struct
-        (PNG_LIBPNG_VER_STRING,0,0,0);
+        throw std::runtime_error("File or stream is not a png");
 
+    png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, 0, 0, 0);
     if (!png_ptr)
-    {
-        throw ImageReaderException("failed to allocate png_ptr");
-    }
+        throw std::runtime_error("failed to allocate png_ptr");
 
     // catch errors in a custom way to avoid the need for setjmp
     png_set_error_fn(png_ptr, png_get_error_ptr(png_ptr), user_error_fn, user_warning_fn);
 
     png_infop info_ptr;
-    png_struct_guard sguard(&png_ptr,&info_ptr);
+    png_struct_guard sguard(&png_ptr, &info_ptr);
     info_ptr = png_create_info_struct(png_ptr);
-    if (!info_ptr) throw ImageReaderException("failed to create info_ptr");
+    if (!info_ptr)
+        throw std::runtime_error("failed to create info_ptr");
 
-    png_set_read_fn(png_ptr, (png_voidp)&stream_, png_read_data);
-
-    png_set_sig_bytes(png_ptr,8);
+    png_set_read_fn(png_ptr, &stream, png_read_data);
+    png_set_sig_bytes(png_ptr, 8);
     png_read_info(png_ptr, info_ptr);
 
-    png_uint_32  w, h;
-    png_get_IHDR(png_ptr, info_ptr, &w, &h, &bit_depth_, &color_type_,0,0,0);
-    has_alpha_ = (color_type_ & PNG_COLOR_MASK_ALPHA) || png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS);
-    width_=w;
-    height_=h;
-}
+    unsigned width = 0;
+    unsigned height = 0;
+    int bit_depth = 0;
+    int color_type = 0;
+    png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type, 0, 0, 0);
 
-template <typename T>
-unsigned PngReader<T>::width() const
-{
-    return width_;
-}
+    PremultipliedImage image { width, height };
 
-template <typename T>
-unsigned PngReader<T>::height() const
-{
-    return height_;
-}
-
-template <typename T>
-std::unique_ptr<uint8_t[]> PngReader<T>::read()
-{
-    std::unique_ptr<uint8_t[]> image = std::make_unique<uint8_t[]>(width_ * height_ * 4);
-
-    stream_.clear();
-    stream_.seekg(0, std::ios_base::beg);
-
-    png_structp png_ptr = png_create_read_struct
-        (PNG_LIBPNG_VER_STRING,0,0,0);
-
-    if (!png_ptr)
-    {
-        throw ImageReaderException("failed to allocate png_ptr");
-    }
-
-    // catch errors in a custom way to avoid the need for setjmp
-    png_set_error_fn(png_ptr, png_get_error_ptr(png_ptr), user_error_fn, user_warning_fn);
-
-    png_infop info_ptr;
-    png_struct_guard sguard(&png_ptr,&info_ptr);
-    info_ptr = png_create_info_struct(png_ptr);
-    if (!info_ptr) throw ImageReaderException("failed to create info_ptr");
-
-    png_set_read_fn(png_ptr, (png_voidp)&stream_, png_read_data);
-    png_read_info(png_ptr, info_ptr);
-
-    if (color_type_ == PNG_COLOR_TYPE_PALETTE)
+    if (color_type == PNG_COLOR_TYPE_PALETTE)
         png_set_expand(png_ptr);
-    if (color_type_ == PNG_COLOR_TYPE_GRAY && bit_depth_ < 8)
+
+    if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
         png_set_expand(png_ptr);
+
     if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS))
         png_set_expand(png_ptr);
-    if (bit_depth_ == 16)
+
+    if (bit_depth == 16)
         png_set_strip_16(png_ptr);
-    if (color_type_ == PNG_COLOR_TYPE_GRAY ||
-        color_type_ == PNG_COLOR_TYPE_GRAY_ALPHA)
+
+    if (color_type == PNG_COLOR_TYPE_GRAY ||
+        color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
         png_set_gray_to_rgb(png_ptr);
 
-    // quick hack -- only work in >=libpng 1.2.7
-    png_set_add_alpha(png_ptr,0xff,PNG_FILLER_AFTER); //rgba
+    png_set_add_alpha(png_ptr, 0xff, PNG_FILLER_AFTER);
 
     double gamma;
     if (png_get_gAMA(png_ptr, info_ptr, &gamma))
@@ -164,19 +116,20 @@ std::unique_ptr<uint8_t[]> PngReader<T>::read()
     png_set_alpha_mode(png_ptr, PNG_ALPHA_PREMULTIPLIED, PNG_GAMMA_LINEAR);
 #endif
 
-    if (png_get_interlace_type(png_ptr,info_ptr) == PNG_INTERLACE_ADAM7)
-    {
+    if (png_get_interlace_type(png_ptr,info_ptr) == PNG_INTERLACE_ADAM7) {
         png_set_interlace_handling(png_ptr); // FIXME: libpng bug?
         // according to docs png_read_image
         // "..automatically handles interlacing,
         // so you don't need to call png_set_interlace_handling()"
     }
+
     png_read_update_info(png_ptr, info_ptr);
+
     // we can read whole image at once
     // alloc row pointers
-    const std::unique_ptr<png_bytep[]> rows(new png_bytep[height_]);
-    for (unsigned row = 0; row < height_; ++row)
-        rows[row] = (png_bytep)image.get() + row * width_ * 4 ;
+    const std::unique_ptr<png_bytep[]> rows(new png_bytep[height]);
+    for (unsigned row = 0; row < height; ++row)
+        rows[row] = image.data.get() + row * width * 4;
     png_read_image(png_ptr, rows.get());
 
 #ifndef PNG_ALPHA_PREMULTIPLIED
@@ -192,11 +145,9 @@ std::unique_ptr<uint8_t[]> PngReader<T>::read()
     }
 #endif
 
-    png_read_end(png_ptr,0);
+    png_read_end(png_ptr, 0);
 
     return image;
 }
 
-template class PngReader<boost::iostreams::array_source>;
-
-}}
+}
diff --git a/platform/node/src/node_map.cpp b/platform/node/src/node_map.cpp
index eb92205487..0ce7d9398b 100644
--- a/platform/node/src/node_map.cpp
+++ b/platform/node/src/node_map.cpp
@@ -3,7 +3,6 @@
 #include "node_mapbox_gl_native.hpp"
 
 #include <mbgl/platform/default/headless_display.hpp>
-#include <mbgl/map/still_image.hpp>
 #include <mbgl/util/exception.hpp>
 #include <mbgl/util/work_request.hpp>
 
@@ -281,7 +280,7 @@ NAN_METHOD(NodeMap::Render) {
     auto options = ParseOptions(info[0]->ToObject());
 
     assert(!nodeMap->callback);
-    assert(!nodeMap->image);
+    assert(!nodeMap->image.data);
     nodeMap->callback = std::make_unique<Nan::Callback>(info[1].As<v8::Function>());
 
     try {
@@ -301,12 +300,12 @@ void NodeMap::startRender(std::unique_ptr<NodeMap::RenderOptions> options) {
     map->setBearing(options->bearing);
     map->setPitch(options->pitch);
 
-    map->renderStill([this](const std::exception_ptr eptr, std::unique_ptr<const mbgl::StillImage> result) {
+    map->renderStill([this](const std::exception_ptr eptr, mbgl::UnassociatedImage&& result) {
         if (eptr) {
             error = std::move(eptr);
             uv_async_send(async);
         } else {
-            assert(!image);
+            assert(!image.data);
             image = std::move(result);
             uv_async_send(async);
         }
@@ -338,7 +337,7 @@ void NodeMap::renderFinished() {
 
     // These have to be empty to be prepared for the next render call.
     assert(!callback);
-    assert(!image);
+    assert(!image.data);
 
     if (error) {
         std::string errorMessage;
@@ -358,17 +357,16 @@ void NodeMap::renderFinished() {
         assert(!error);
 
         cb->Call(1, argv);
-    } else if (img) {
+    } else if (img.data) {
         v8::Local<v8::Object> pixels = Nan::NewBuffer(
-            reinterpret_cast<char *>(img->pixels.get()), img->width * img->height * 4,
-
-            // Retain the StillImage object until the buffer is deleted.
-            [](char *, void *hint) {
-                delete reinterpret_cast<const mbgl::StillImage *>(hint);
+            reinterpret_cast<char *>(img.data.get()), img.size(),
+            // Retain the data until the buffer is deleted.
+            [](char *, void * hint) {
+                delete [] reinterpret_cast<uint8_t*>(hint);
             },
-            const_cast<mbgl::StillImage *>(img.get())
+            img.data.get()
         ).ToLocalChecked();
-        img.release();
+        img.data.release();
 
         v8::Local<v8::Value> argv[] = {
             Nan::Null(),
diff --git a/platform/node/src/node_map.hpp b/platform/node/src/node_map.hpp
index f610408d3f..455d38e957 100644
--- a/platform/node/src/node_map.hpp
+++ b/platform/node/src/node_map.hpp
@@ -49,7 +49,7 @@ public:
     std::unique_ptr<mbgl::Map> map;
 
     std::exception_ptr error;
-    std::unique_ptr<const mbgl::StillImage> image;
+    mbgl::UnassociatedImage image;
     std::unique_ptr<Nan::Callback> callback;
 
     // Async for delivering the notifications of render completion.
diff --git a/src/mbgl/map/map_context.cpp b/src/mbgl/map/map_context.cpp
index cf06dd06eb..f00b3eaf55 100644
--- a/src/mbgl/map/map_context.cpp
+++ b/src/mbgl/map/map_context.cpp
@@ -1,7 +1,6 @@
 #include <mbgl/map/map_context.hpp>
 #include <mbgl/map/map_data.hpp>
 #include <mbgl/map/view.hpp>
-#include <mbgl/map/still_image.hpp>
 
 #include <mbgl/platform/log.hpp>
 
@@ -200,22 +199,22 @@ void MapContext::renderStill(const TransformState& state, const FrameData& frame
     }
 
     if (data.mode != MapMode::Still) {
-        fn(std::make_exception_ptr(util::MisuseException("Map is not in still image render mode")), nullptr);
+        fn(std::make_exception_ptr(util::MisuseException("Map is not in still image render mode")), {});
         return;
     }
 
     if (callback) {
-        fn(std::make_exception_ptr(util::MisuseException("Map is currently rendering an image")), nullptr);
+        fn(std::make_exception_ptr(util::MisuseException("Map is currently rendering an image")), {});
         return;
     }
 
     if (!style) {
-        fn(std::make_exception_ptr(util::MisuseException("Map doesn't have a style")), nullptr);
+        fn(std::make_exception_ptr(util::MisuseException("Map doesn't have a style")), {});
         return;
     }
 
     if (style->getLastError()) {
-        fn(style->getLastError(), nullptr);
+        fn(style->getLastError(), {});
         return;
     }
 
@@ -246,7 +245,7 @@ bool MapContext::renderSync(const TransformState& state, const FrameData& frame)
     painter->render(*style, frame);
 
     if (data.mode == MapMode::Still) {
-        callback(nullptr, view.readStillImage());
+        callback(nullptr, std::move(view.readStillImage()));
         callback = nullptr;
     }
 
@@ -320,7 +319,7 @@ void MapContext::onResourceLoadingFailed(std::exception_ptr error) {
     assert(util::ThreadContext::currentlyOn(util::ThreadType::Map));
 
     if (data.mode == MapMode::Still && callback) {
-        callback(error, nullptr);
+        callback(error, {});
         callback = nullptr;
     }
 }
diff --git a/src/mbgl/map/view.cpp b/src/mbgl/map/view.cpp
index 5da290534a..fa8b7584cc 100644
--- a/src/mbgl/map/view.cpp
+++ b/src/mbgl/map/view.cpp
@@ -1,6 +1,5 @@
 #include <mbgl/map/view.hpp>
 #include <mbgl/map/map.hpp>
-#include <mbgl/map/still_image.hpp>
 
 #include <cassert>
 
@@ -11,8 +10,8 @@ void View::initialize(Map *map_) {
     map = map_;
 }
 
-std::unique_ptr<StillImage> View::readStillImage() {
-    return nullptr;
+UnassociatedImage View::readStillImage() {
+    return {};
 }
 
 void View::notifyMapChange(MapChange) {
diff --git a/src/mbgl/renderer/raster_bucket.cpp b/src/mbgl/renderer/raster_bucket.cpp
index 4a7dfeda05..37e5c31cc4 100644
--- a/src/mbgl/renderer/raster_bucket.cpp
+++ b/src/mbgl/renderer/raster_bucket.cpp
@@ -23,7 +23,7 @@ void RasterBucket::render(Painter& painter,
     painter.renderRaster(*this, dynamic_cast<const RasterLayer&>(layer), id, matrix);
 }
 
-bool RasterBucket::setImage(std::unique_ptr<util::Image> image) {
+bool RasterBucket::setImage(PremultipliedImage image) {
     return raster.load(std::move(image));
 }
 
diff --git a/src/mbgl/renderer/raster_bucket.hpp b/src/mbgl/renderer/raster_bucket.hpp
index 2882a94bbd..e12257d864 100644
--- a/src/mbgl/renderer/raster_bucket.hpp
+++ b/src/mbgl/renderer/raster_bucket.hpp
@@ -18,7 +18,7 @@ public:
     void render(Painter&, const StyleLayer&, const TileID&, const mat4&) override;
     bool hasData() const override;
 
-    bool setImage(std::unique_ptr<util::Image> image);
+    bool setImage(PremultipliedImage);
 
     void drawRaster(RasterShader& shader, StaticVertexBuffer &vertices, VertexArrayObject &array);
 
diff --git a/src/mbgl/sprite/sprite_parser.cpp b/src/mbgl/sprite/sprite_parser.cpp
index a8ed4f0e12..3b6464be9e 100644
--- a/src/mbgl/sprite/sprite_parser.cpp
+++ b/src/mbgl/sprite/sprite_parser.cpp
@@ -14,7 +14,7 @@
 
 namespace mbgl {
 
-SpriteImagePtr createSpriteImage(const util::Image& image,
+SpriteImagePtr createSpriteImage(const PremultipliedImage& image,
                                  const uint16_t srcX,
                                  const uint16_t srcY,
                                  const uint16_t srcWidth,
@@ -37,18 +37,18 @@ SpriteImagePtr createSpriteImage(const util::Image& image,
 
     std::string data(dstWidth * dstHeight * 4, '\0');
 
-    auto srcData = reinterpret_cast<const uint32_t*>(image.getData());
+    auto srcData = reinterpret_cast<const uint32_t*>(image.data.get());
     auto dstData = reinterpret_cast<uint32_t*>(const_cast<char*>(data.data()));
 
-    const int32_t maxX = std::min(image.getWidth(), uint32_t(srcWidth + srcX)) - srcX;
-    assert(maxX <= int32_t(image.getWidth()));
-    const int32_t maxY = std::min(image.getHeight(), uint32_t(srcHeight + srcY)) - srcY;
-    assert(maxY <= int32_t(image.getHeight()));
+    const int32_t maxX = std::min(uint32_t(image.width), uint32_t(srcWidth + srcX)) - srcX;
+    assert(maxX <= int32_t(image.width));
+    const int32_t maxY = std::min(uint32_t(image.height), uint32_t(srcHeight + srcY)) - srcY;
+    assert(maxY <= int32_t(image.height));
 
     // Copy from the source image into our individual sprite image
     for (uint16_t y = 0; y < maxY; ++y) {
         const auto dstRow = y * dstWidth;
-        const auto srcRow = (y + srcY) * image.getWidth() + srcX;
+        const auto srcRow = (y + srcY) * image.width + srcX;
         for (uint16_t x = 0; x < maxX; ++x) {
             dstData[dstRow + x] = srcData[srcRow + x];
         }
@@ -105,10 +105,11 @@ SpriteParseResult parseSprite(const std::string& image, const std::string& json)
     using namespace rapidjson;
 
     Sprites sprites;
+    PremultipliedImage raster;
 
-    // Parse the sprite image.
-    const util::Image raster(image);
-    if (!raster) {
+    try {
+        raster = decodeImage(image);
+    } catch (...) {
         return std::string("Could not parse sprite image");
     }
 
diff --git a/src/mbgl/sprite/sprite_parser.hpp b/src/mbgl/sprite/sprite_parser.hpp
index d385d77aea..468ba13c53 100644
--- a/src/mbgl/sprite/sprite_parser.hpp
+++ b/src/mbgl/sprite/sprite_parser.hpp
@@ -3,6 +3,7 @@
 
 #include <mapbox/variant.hpp>
 
+#include <mbgl/util/image.hpp>
 #include <mbgl/util/noncopyable.hpp>
 #include <mbgl/util/geo.hpp>
 
@@ -12,18 +13,12 @@
 
 namespace mbgl {
 
-namespace util {
-
-class Image;
-
-} // namespace util
-
 class SpriteImage;
 
 using SpriteImagePtr = std::shared_ptr<const SpriteImage>;
 
 // Extracts an individual image from a spritesheet from the given location.
-SpriteImagePtr createSpriteImage(const util::Image& image,
+SpriteImagePtr createSpriteImage(const PremultipliedImage&,
                                  uint16_t srcX,
                                  uint16_t srcY,
                                  uint16_t srcWidth,
diff --git a/src/mbgl/util/raster.cpp b/src/mbgl/util/raster.cpp
index 1c277040cd..c4d65ff320 100644
--- a/src/mbgl/util/raster.cpp
+++ b/src/mbgl/util/raster.cpp
@@ -25,13 +25,13 @@ bool Raster::isLoaded() const {
     return loaded;
 }
 
-bool Raster::load(std::unique_ptr<util::Image> image) {
+bool Raster::load(PremultipliedImage image) {
     img = std::move(image);
-    width = img->getWidth();
-    height = img->getHeight();
+    width = GLsizei(img.width);
+    height = GLsizei(img.height);
 
     std::lock_guard<std::mutex> lock(mtx);
-    if (img->getData()) {
+    if (img.data.get()) {
         loaded = true;
     }
     return loaded;
@@ -44,7 +44,7 @@ void Raster::bind(bool linear) {
         return;
     }
 
-    if (img && !textured) {
+    if (img.data && !textured) {
         upload();
     } else if (textured) {
         MBGL_CHECK_ERROR(glBindTexture(GL_TEXTURE_2D, texture));
@@ -59,7 +59,7 @@ void Raster::bind(bool linear) {
 }
 
 void Raster::upload() {
-    if (img && !textured) {
+    if (img.data && !textured) {
         texture = texturePool.getTextureID();
         MBGL_CHECK_ERROR(glBindTexture(GL_TEXTURE_2D, texture));
 #ifndef GL_ES_VERSION_2_0
@@ -67,8 +67,8 @@ void Raster::upload() {
 #endif
         MBGL_CHECK_ERROR(glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE));
         MBGL_CHECK_ERROR(glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE));
-        MBGL_CHECK_ERROR(glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, img->getData()));
-        img.reset();
+        MBGL_CHECK_ERROR(glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, img.data.get()));
+        img.data.reset();
         textured = true;
     }
 }
diff --git a/src/mbgl/util/raster.hpp b/src/mbgl/util/raster.hpp
index adf3b2cbf7..5c65c46e9d 100644
--- a/src/mbgl/util/raster.hpp
+++ b/src/mbgl/util/raster.hpp
@@ -20,7 +20,7 @@ public:
     ~Raster();
 
     // load image data
-    bool load(std::unique_ptr<util::Image> image);
+    bool load(PremultipliedImage);
 
     // bind current texture
     void bind(bool linear = false);
@@ -58,7 +58,7 @@ private:
     GLint filter = 0;
 
     // the raw pixels
-    std::unique_ptr<util::Image> img;
+    PremultipliedImage img;
 };
 
 }
diff --git a/src/mbgl/util/worker.cpp b/src/mbgl/util/worker.cpp
index 9940fb649c..00bdb5baee 100644
--- a/src/mbgl/util/worker.cpp
+++ b/src/mbgl/util/worker.cpp
@@ -17,8 +17,11 @@ public:
     void parseRasterTile(std::unique_ptr<RasterBucket> bucket,
                          const std::shared_ptr<const std::string> data,
                          std::function<void(RasterTileParseResult)> callback) {
-        std::unique_ptr<util::Image> image(new util::Image(*data));
-        if (!(*image)) {
+        PremultipliedImage image;
+
+        try {
+            image = decodeImage(*data);
+        } catch (...) {
             callback(RasterTileParseResult("error parsing raster image"));
         }
 
diff --git a/test/api/annotations.cpp b/test/api/annotations.cpp
index 55f5ca6749..b16ec71ef6 100644
--- a/test/api/annotations.cpp
+++ b/test/api/annotations.cpp
@@ -4,7 +4,6 @@
 #include <mbgl/annotation/shape_annotation.hpp>
 #include <mbgl/sprite/sprite_image.hpp>
 #include <mbgl/map/map.hpp>
-#include <mbgl/map/still_image.hpp>
 #include <mbgl/platform/default/headless_display.hpp>
 #include <mbgl/platform/default/headless_view.hpp>
 #include <mbgl/storage/default_file_source.hpp>
@@ -17,13 +16,11 @@
 using namespace mbgl;
 
 std::string renderPNG(Map& map) {
-    std::promise<std::unique_ptr<const StillImage>> promise;
-    map.renderStill([&](std::exception_ptr, std::unique_ptr<const StillImage> image) {
+    std::promise<UnassociatedImage> promise;
+    map.renderStill([&](std::exception_ptr, UnassociatedImage&& image) {
         promise.set_value(std::move(image));
     });
-
-    auto result = promise.get_future().get();
-    return util::compress_png(result->width, result->height, result->pixels.get());
+    return encodePNG(promise.get_future().get());
 }
 
 TEST(Annotations, PointAnnotation) {
diff --git a/test/api/api_misuse.cpp b/test/api/api_misuse.cpp
index 1f54855323..4d5fe11042 100644
--- a/test/api/api_misuse.cpp
+++ b/test/api/api_misuse.cpp
@@ -2,7 +2,6 @@
 #include "../fixtures/fixture_log_observer.hpp"
 
 #include <mbgl/map/map.hpp>
-#include <mbgl/map/still_image.hpp>
 #include <mbgl/platform/default/headless_display.hpp>
 #include <mbgl/platform/default/headless_view.hpp>
 #include <mbgl/storage/default_file_source.hpp>
@@ -46,7 +45,7 @@ TEST(API, RenderWithoutStyle) {
     Map map(view, fileSource, MapMode::Still);
 
     std::promise<std::exception_ptr> promise;
-    map.renderStill([&promise](std::exception_ptr error, std::unique_ptr<const StillImage>) {
+    map.renderStill([&promise](std::exception_ptr error, UnassociatedImage&&) {
         promise.set_value(error);
     });
 
diff --git a/test/api/repeated_render.cpp b/test/api/repeated_render.cpp
index 3317b4e3a4..79349c67e7 100644
--- a/test/api/repeated_render.cpp
+++ b/test/api/repeated_render.cpp
@@ -2,7 +2,6 @@
 #include "../fixtures/fixture_log_observer.hpp"
 
 #include <mbgl/map/map.hpp>
-#include <mbgl/map/still_image.hpp>
 #include <mbgl/platform/default/headless_view.hpp>
 #include <mbgl/platform/default/headless_display.hpp>
 #include <mbgl/storage/default_file_source.hpp>
@@ -26,28 +25,26 @@ TEST(API, RepeatedRender) {
 
     {
         map.setStyleJSON(style, "");
-        std::promise<std::unique_ptr<const StillImage>> promise;
-        map.renderStill([&promise](std::exception_ptr, std::unique_ptr<const StillImage> image) {
+        std::promise<UnassociatedImage> promise;
+        map.renderStill([&promise](std::exception_ptr, UnassociatedImage&& image) {
             promise.set_value(std::move(image));
         });
-        auto result = promise.get_future().get();
-        ASSERT_EQ(256, result->width);
-        ASSERT_EQ(512, result->height);
-        const std::string png = util::compress_png(result->width, result->height, result->pixels.get());
-        util::write_file("test/fixtures/api/1.png", png);
+        auto result = std::move(promise.get_future().get());
+        ASSERT_EQ(256, result.width);
+        ASSERT_EQ(512, result.height);
+        util::write_file("test/fixtures/api/1.png", encodePNG(result));
     }
 
     {
         map.setStyleJSON(style, "TEST_DATA/suite");
-        std::promise<std::unique_ptr<const StillImage>> promise;
-        map.renderStill([&promise](std::exception_ptr, std::unique_ptr<const StillImage> image) {
+        std::promise<UnassociatedImage> promise;
+        map.renderStill([&promise](std::exception_ptr, UnassociatedImage&& image) {
             promise.set_value(std::move(image));
         });
-        auto result = promise.get_future().get();
-        ASSERT_EQ(256, result->width);
-        ASSERT_EQ(512, result->height);
-        const std::string png = util::compress_png(result->width, result->height, result->pixels.get());
-        util::write_file("test/fixtures/api/2.png", png);
+        auto result = std::move(promise.get_future().get());
+        ASSERT_EQ(256, result.width);
+        ASSERT_EQ(512, result.height);
+        util::write_file("test/fixtures/api/2.png", encodePNG(result));
     }
 
     auto observer = Log::removeObserver();
diff --git a/test/miscellaneous/bilinear.cpp b/test/miscellaneous/bilinear.cpp
index 722e7265c0..740025bbbc 100644
--- a/test/miscellaneous/bilinear.cpp
+++ b/test/miscellaneous/bilinear.cpp
@@ -23,8 +23,9 @@ TEST(Bilinear, Scaling) {
     const uint32_t *srcData = reinterpret_cast<const uint32_t *>(src + 8);
     const vec2<uint32_t> srcSize { width, height };
     const vec2<uint32_t> dstSize { 128, 128 };
-    auto dst = std::make_unique<uint32_t[]>(dstSize.x * dstSize.y);
-    uint32_t *dstData = dst.get();
+
+    UnassociatedImage dst { dstSize.x, dstSize.y };
+    uint32_t *dstData = reinterpret_cast<uint32_t*>(dst.data.get());
     std::fill(dstData, dstData + dstSize.x * dstSize.y, 0xFFFF00FF);
 
     util::bilinearScale(srcData, srcSize, { 0, 0, 24, 24 }, dstData, dstSize, { 8, 8, 24, 24 }, false);
@@ -42,7 +43,7 @@ TEST(Bilinear, Scaling) {
     util::bilinearScale(srcData, srcSize, { 252, 380, 12, 12 }, dstData, dstSize, { 18, 90, 24, 24 }, false);
 
     const std::string data { reinterpret_cast<char *>(dstData), dstSize.x * dstSize.y * sizeof(uint32_t) };
-    util::write_file("test/fixtures/sprites/atlas_actual.png", util::compress_png(dstSize.x, dstSize.y, reinterpret_cast<uint8_t *>(dstData)));
+    util::write_file("test/fixtures/sprites/atlas_actual.png", encodePNG(dst));
     util::write_file("test/fixtures/sprites/atlas_actual.bin", util::compress(data));
 
     const std::string reference = util::decompress(util::read_file("test/fixtures/sprites/atlas_reference.bin"));
diff --git a/test/sprite/sprite_parser.cpp b/test/sprite/sprite_parser.cpp
index c2e4df3c58..dfa3a1055b 100644
--- a/test/sprite/sprite_parser.cpp
+++ b/test/sprite/sprite_parser.cpp
@@ -13,10 +13,10 @@ using namespace mbgl;
 TEST(Sprite, SpriteImageCreationInvalid) {
     FixtureLog log;
 
-    const util::Image image_1x(util::read_file("test/fixtures/annotations/emerald.png"));
-    ASSERT_TRUE(image_1x);
-    ASSERT_EQ(200u, image_1x.getWidth());
-    ASSERT_EQ(299u, image_1x.getHeight());
+    const PremultipliedImage image_1x = decodeImage(util::read_file("test/fixtures/annotations/emerald.png"));
+
+    ASSERT_EQ(200u, image_1x.width);
+    ASSERT_EQ(299u, image_1x.height);
 
     ASSERT_EQ(nullptr, createSpriteImage(image_1x, 0, 0, 0, 16, 1, false));    // width == 0
     ASSERT_EQ(nullptr, createSpriteImage(image_1x, 0, 0, 16, 0, 1, false));    // height == 0
@@ -34,10 +34,10 @@ TEST(Sprite, SpriteImageCreationInvalid) {
 }
 
 TEST(Sprite, SpriteImageCreation1x) {
-    const util::Image image_1x(util::read_file("test/fixtures/annotations/emerald.png"));
-    ASSERT_TRUE(image_1x);
-    ASSERT_EQ(200u, image_1x.getWidth());
-    ASSERT_EQ(299u, image_1x.getHeight());
+    const PremultipliedImage image_1x = decodeImage(util::read_file("test/fixtures/annotations/emerald.png"));
+
+    ASSERT_EQ(200u, image_1x.width);
+    ASSERT_EQ(299u, image_1x.height);
 
     { // "museum_icon":{"x":177,"y":187,"width":18,"height":18,"pixelRatio":1,"sdf":false}
         const auto sprite = createSpriteImage(image_1x, 177, 187, 18, 18, 1, false);
@@ -74,8 +74,7 @@ TEST(Sprite, SpriteImageCreation1x) {
 }
 
 TEST(Sprite, SpriteImageCreation2x) {
-    const util::Image image_2x(util::read_file("test/fixtures/annotations/emerald@2x.png"));
-    ASSERT_TRUE(image_2x);
+    const PremultipliedImage image_2x = decodeImage(util::read_file("test/fixtures/annotations/emerald@2x.png"));
 
     // "museum_icon":{"x":354,"y":374,"width":36,"height":36,"pixelRatio":2,"sdf":false}
     const auto sprite = createSpriteImage(image_2x, 354, 374, 36, 36, 2, false);
@@ -89,8 +88,7 @@ TEST(Sprite, SpriteImageCreation2x) {
 }
 
 TEST(Sprite, SpriteImageCreation1_5x) {
-    const util::Image image_2x(util::read_file("test/fixtures/annotations/emerald@2x.png"));
-    ASSERT_TRUE(image_2x);
+    const PremultipliedImage image_2x = decodeImage(util::read_file("test/fixtures/annotations/emerald@2x.png"));
 
     // "museum_icon":{"x":354,"y":374,"width":36,"height":36,"pixelRatio":2,"sdf":false}
     const auto sprite = createSpriteImage(image_2x, 354, 374, 36, 36, 1.5, false);
diff --git a/test/style/pending_resources.cpp b/test/style/pending_resources.cpp
index 3ba59657de..58dc72937e 100644
--- a/test/style/pending_resources.cpp
+++ b/test/style/pending_resources.cpp
@@ -3,7 +3,6 @@
 #include "../fixtures/util.hpp"
 
 #include <mbgl/map/map.hpp>
-#include <mbgl/map/still_image.hpp>
 #include <mbgl/platform/default/headless_display.hpp>
 #include <mbgl/platform/default/headless_view.hpp>
 #include <mbgl/util/io.hpp>
@@ -40,7 +39,7 @@ TEST_P(PendingResources, DeleteMapObjectWithPendingRequest) {
     const std::string style = util::read_file("test/fixtures/resources/style.json");
     map->setStyleJSON(style, ".");
 
-    map->renderStill([&endTest](std::exception_ptr, std::unique_ptr<const StillImage>) {
+    map->renderStill([&endTest](std::exception_ptr, UnassociatedImage&&) {
         EXPECT_TRUE(false) << "Should never happen.";
     });