1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
|
/****************************************************************************
**
** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the Qt Graphical Effects module.
**
** $QT_BEGIN_LICENSE:BSD$
** You may use this file under the terms of the BSD license as follows:
**
** "Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are
** met:
** * Redistributions of source code must retain the above copyright
** notice, this list of conditions and the following disclaimer.
** * Redistributions in binary form must reproduce the above copyright
** notice, this list of conditions and the following disclaimer in
** the documentation and/or other materials provided with the
** distribution.
** * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names
** of its contributors may be used to endorse or promote products derived
** from this software without specific prior written permission.
**
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
**
** $QT_END_LICENSE$
**
****************************************************************************/
import QtQuick 2.0
import "private"
/*!
\qmltype GammaAdjust
\inqmlmodule QtGraphicalEffects
\since QtGraphicalEffects 1.0
\inherits QtQuick2::Item
\ingroup qtgraphicaleffects-color
\brief Alters the luminance of the source item.
GammaAdjust is applied to each pixel according to the curve which is
pre-defined as a power-law expression, where the property gamma is used as the
reciprocal scaling exponent. Refer to the property documentation of \l{GammaAdjust::gamma}{gamma}
for more details.
\table
\header
\li Source
\li Effect applied
\row
\li \image Original_bug.png
\li \image GammaAdjust_bug.png
\endtable
\section1 Example
The following example shows how to apply the effect.
\snippet GammaAdjust-example.qml example
*/
Item {
id: rootItem
/*!
This property defines the source item for which the luminance is going to be
adjusted.
\note It is not supported to let the effect include itself, for
instance by setting source to the effect's parent.
*/
property variant source
/*!
This property defines the change factor for how the luminance of each pixel
is altered according to the equation:
\code
luminance = pow(original_luminance, 1.0 / gamma); // The luminance is assumed to be between 0.0 and 1.0
\endcode
Setting the gamma values under 1.0 makes the image darker, the values
above 1.0 lighten it.
The value ranges from 0.0 (darkest) to inf (lightest). By default, the
property is set to \c 1.0 (no change).
\table
\header
\li Output examples with different gamma values
\li
\li
\row
\li \image GammaAdjust_gamma1.png
\li \image GammaAdjust_gamma2.png
\li \image GammaAdjust_gamma3.png
\row
\li \b { gamma: 0.5 }
\li \b { gamma: 1.0 }
\li \b { gamma: 2.0 }
\endtable
\table
\header
\li Pixel luminance curves of the above images.
\li
\li
\row
\li \image GammaAdjust_gamma1_graph.png
\li \image GammaAdjust_gamma2_graph.png
\li \image GammaAdjust_gamma3_graph.png
\row
\li Red curve: default gamma (1.0)
\li
\li
\row
\li Yellow curve: effect applied
\li
\li
\row
\li X-axis: pixel original luminance
\li
\li
\row
\li Y-axis: pixel luminance with effect applied
\li
\li
\endtable
*/
property real gamma: 1.0
/*!
This property allows the effect output pixels to be cached in order to
improve the rendering performance.
Every time the source or effect properties are changed, the pixels in
the cache must be updated. Memory consumption is increased, because an
extra buffer of memory is required for storing the effect output.
It is recommended to disable the cache when the source or the effect
properties are animated.
By default, the property is set to \c false.
*/
property bool cached: false
SourceProxy {
id: sourceProxy
input: rootItem.source
}
ShaderEffectSource {
id: cacheItem
anchors.fill: parent
visible: rootItem.cached
smooth: true
sourceItem: shaderItem
live: true
hideSource: visible
}
ShaderEffect {
id: shaderItem
property variant source: sourceProxy.output
property real gamma: 1.0 / Math.max(rootItem.gamma, 0.0001)
anchors.fill: parent
fragmentShader: "
varying highp vec2 qt_TexCoord0;
uniform highp float qt_Opacity;
uniform lowp sampler2D source;
uniform highp float gamma;
void main(void) {
highp vec4 originalColor = texture2D(source, qt_TexCoord0.st);
originalColor.rgb = originalColor.rgb / max(1.0/256.0, originalColor.a);
highp vec3 adjustedColor = pow(originalColor.rgb, vec3(gamma));
gl_FragColor = vec4(adjustedColor * originalColor.a, originalColor.a) * qt_Opacity;
}
"
}
}
|
