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When doing a perfect po2 nearest neighbor downsample don't allow -0.5 and 0.5 to both contribute to a texel or you'll get a double tap.

pull/32/head
Jorge Rodriguez 2014-07-30 09:27:42 -07:00
parent c2449acc3e
commit 985ac75251
2 changed files with 18 additions and 5 deletions
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10
stb_resample.h
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@ -331,12 +331,12 @@ float stbr__linear_to_srgb(float f)
static float stbr__filter_nearest(float x)
{
x = (float)fabs(x);
if (x <= 0.5)
return 1;
else
if (x <= -0.5f)
return 0;
else if (x > 0.5f)
return 0;
else
return 1;
}
static float stbr__filter_bilinear(float x)

13
tests/resample_test.cpp
View File

@ -227,6 +227,19 @@ void test_suite()
resize_image("gamma_2.2.jpg", .5f, .5f, STBR_FILTER_CATMULLROM, STBR_EDGE_REFLECT, STBR_COLORSPACE_SRGB, "test-output/gamma_2.2.jpg");
resize_image("gamma_dalai_lama_gray.jpg", .5f, .5f, STBR_FILTER_CATMULLROM, STBR_EDGE_REFLECT, STBR_COLORSPACE_SRGB, "test-output/gamma_dalai_lama_gray.jpg");
// filter tests
resize_image("barbara.png", 2, 2, STBR_FILTER_NEAREST, STBR_EDGE_CLAMP, STBR_COLORSPACE_SRGB, "test-output/barbara-upsample-nearest.png");
resize_image("barbara.png", 2, 2, STBR_FILTER_BILINEAR, STBR_EDGE_CLAMP, STBR_COLORSPACE_SRGB, "test-output/barbara-upsample-bilinear.png");
resize_image("barbara.png", 2, 2, STBR_FILTER_BICUBIC, STBR_EDGE_CLAMP, STBR_COLORSPACE_SRGB, "test-output/barbara-upsample-bicubic.png");
resize_image("barbara.png", 2, 2, STBR_FILTER_CATMULLROM, STBR_EDGE_CLAMP, STBR_COLORSPACE_SRGB, "test-output/barbara-upsample-catmullrom.png");
resize_image("barbara.png", 2, 2, STBR_FILTER_MITCHELL, STBR_EDGE_CLAMP, STBR_COLORSPACE_SRGB, "test-output/barbara-upsample-mitchell.png");
resize_image("barbara.png", 0.5f, 0.5f, STBR_FILTER_NEAREST, STBR_EDGE_CLAMP, STBR_COLORSPACE_SRGB, "test-output/barbara-downsample-nearest.png");
resize_image("barbara.png", 0.5f, 0.5f, STBR_FILTER_BILINEAR, STBR_EDGE_CLAMP, STBR_COLORSPACE_SRGB, "test-output/barbara-downsample-bilinear.png");
resize_image("barbara.png", 0.5f, 0.5f, STBR_FILTER_BICUBIC, STBR_EDGE_CLAMP, STBR_COLORSPACE_SRGB, "test-output/barbara-downsample-bicubic.png");
resize_image("barbara.png", 0.5f, 0.5f, STBR_FILTER_CATMULLROM, STBR_EDGE_CLAMP, STBR_COLORSPACE_SRGB, "test-output/barbara-downsample-catmullrom.png");
resize_image("barbara.png", 0.5f, 0.5f, STBR_FILTER_MITCHELL, STBR_EDGE_CLAMP, STBR_COLORSPACE_SRGB, "test-output/barbara-downsample-mitchell.png");
for (int i = 10; i < 100; i++)
{
char outname[200];