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fix(idiff): Fail comparison when images have different dimensions #4976

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Merged
lgritz merged 1 commit into from
Dec 17, 2025
+8 −8
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fix(idiff): Fail comparison when images have different dimensions #4976

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4 changes: 2 additions & 2 deletions src/libOpenImageIO/imagebufalgo_yee.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -52,7 +52,7 @@ class GaussianPyramid {
if (lev >= PYRAMID_MAX_LEVELS)
return 0.0f;
else
return level[lev].getchannel(x, y, 0, 1);
return level[lev].getchannel(x, y, 0, 0);
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@lgritz lgritz Dec 12, 2025

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It was this all along? Weird. Why did this ever work?

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@pmady pmady Dec 15, 2025

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"It 'worked' in the sense that it didn't crash - getchannel() likely returns 0 for out-of-bounds channels. Since both pyramids returned the same incorrect value (0), the computed differences were always 0, making images appear identical. This explains why perceptual comparison was passing for clearly different images in #4948."

}

#if 0 /* unused */
Expand All @@ -65,7 +65,7 @@ class GaussianPyramid {
float operator()(int x, int y, int lev) const
{
OIIO_DASSERT(lev < PYRAMID_MAX_LEVELS);
return level[lev].getchannel(x, y, 0, 1);
return level[lev].getchannel(x, y, 0, 0);
}
#endif

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6 changes: 3 additions & 3 deletions testsuite/diff/ref/out-fmt6.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -16,7 +16,7 @@ Computing diff of "img1.exr" vs "img2.exr"
121 pixels (2.95%) over 1e-06
FAILURE
Computing perceptual diff of "img1.exr" vs "img2.exr"
Max error = 1.0 @ (5, 17, R) values are 0.1, 0.1, 0.1 vs 0.1, 0.6, 0.1
Max error = 10.0 @ (5, 17, R) values are 0.1, 0.1, 0.1 vs 0.1, 0.6, 0.1
121 pixels (2.95%) failed the perceptual test
FAILURE
Computing perceptual diff of "img1.exr" vs "img1.exr"
Expand All @@ -26,7 +26,7 @@ Comparing "img1.exr" and "img2.exr"
Mean error = 0
RMS error = 0
Peak SNR = 0
Max error = 1 @ (5, 17, R) values are 0.1, 0.1, 0.1 vs 0.1, 0.6, 0.1
Max error = 10 @ (5, 17, R) values are 0.1, 0.1, 0.1 vs 0.1, 0.6, 0.1
0 pixels (0%) over 0.008
121 pixels (2.95%) over 0.004
121 pixels (2.9541%) failed the perceptual test
Expand All @@ -38,7 +38,7 @@ Comparing "img1.exr" and "img2.exr"
Mean error = 0
RMS error = 0
Peak SNR = 0
Max error = 1 @ (5, 17, R) values are 0.1, 0.1, 0.1 vs 0.1, 0.6, 0.1
Max error = 10 @ (5, 17, R) values are 0.1, 0.1, 0.1 vs 0.1, 0.6, 0.1
0 pixels (0%) over 0.008
121 pixels (2.95%) over 1.0
121 pixels (2.9541%) failed the perceptual test
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6 changes: 3 additions & 3 deletions testsuite/diff/ref/out.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -16,7 +16,7 @@ Computing diff of "img1.exr" vs "img2.exr"
121 pixels (2.95%) over 1e-06
FAILURE
Computing perceptual diff of "img1.exr" vs "img2.exr"
Max error = 1 @ (5, 17, R) values are 0.1, 0.1, 0.1 vs 0.1, 0.6, 0.1
Max error = 10 @ (5, 17, R) values are 0.1, 0.1, 0.1 vs 0.1, 0.6, 0.1
121 pixels (2.95%) failed the perceptual test
FAILURE
Computing perceptual diff of "img1.exr" vs "img1.exr"
Expand All @@ -26,7 +26,7 @@ Comparing "img1.exr" and "img2.exr"
Mean error = 0
RMS error = 0
Peak SNR = 0
Max error = 1 @ (5, 17, R) values are 0.1, 0.1, 0.1 vs 0.1, 0.6, 0.1
Max error = 10 @ (5, 17, R) values are 0.1, 0.1, 0.1 vs 0.1, 0.6, 0.1
0 pixels (0%) over 0.008
121 pixels (2.95%) over 0.004
121 pixels (2.9541%) failed the perceptual test
Expand All @@ -38,7 +38,7 @@ Comparing "img1.exr" and "img2.exr"
Mean error = 0
RMS error = 0
Peak SNR = 0
Max error = 1 @ (5, 17, R) values are 0.1, 0.1, 0.1 vs 0.1, 0.6, 0.1
Max error = 10 @ (5, 17, R) values are 0.1, 0.1, 0.1 vs 0.1, 0.6, 0.1
0 pixels (0%) over 0.008
121 pixels (2.95%) over 1
121 pixels (2.9541%) failed the perceptual test
Expand Down
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