1 /**************************************************************************
3 * Copyright 2011 Jose Fonseca
4 * Copyright 2008-2010 VMware, Inc.
7 * Permission is hereby granted, free of charge, to any person obtaining a copy
8 * of this software and associated documentation files (the "Software"), to deal
9 * in the Software without restriction, including without limitation the rights
10 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
11 * copies of the Software, and to permit persons to whom the Software is
12 * furnished to do so, subject to the following conditions:
14 * The above copyright notice and this permission notice shall be included in
15 * all copies or substantial portions of the Software.
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
20 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
25 **************************************************************************/
39 double Image::compare(Image &ref)
41 if (width != ref.width ||
42 height != ref.height ||
48 // Ignore missing alpha when comparing RGB w/ RGBA, but enforce an equal
49 // number of channels otherwise.
50 unsigned minChannels = std::min(channels, ref.channels);
51 if (channels != ref.channels && minChannels < 3) {
55 const unsigned char *pSrc = start();
56 const unsigned char *pRef = ref.start();
58 unsigned long long error = 0;
59 for (unsigned y = 0; y < height; ++y) {
60 for (unsigned x = 0; x < width; ++x) {
61 // FIXME: Ignore alpha channel until we are able to pick a visual
62 // that matches the traces
63 for (unsigned c = 0; c < minChannels; ++c) {
64 int delta = pSrc[x*channels + c] - pRef[x*ref.channels + c];
73 double numerator = error*2 + 1;
74 double denominator = height*width*minChannels*255ULL*255ULL*2;
75 double quotient = numerator/denominator;
78 double precision = -log(quotient)/log(2.0);
84 } /* namespace image */