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I had the whole premultiply thing backwards.

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This commit is contained in:
Jorge Rodriguez
2014-07-31 18:46:00 -07:00
parent 21c7c8f5d9
commit 13acfca829
2 changed files with 49 additions and 41 deletions
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26
tests/resample_test.cpp
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@ -286,11 +286,14 @@ void test_premul(const char* file)
unsigned char* input_data = stbi_load(file, &w, &h, &n, 4);
n = 4;
// Premultiply the first texel.
input_data[0] /= 2;
input_data[1] /= 2;
input_data[2] /= 2;
input_data[3] = 255 / 2;
// Set alpha for the top half.
for (int x = 0; x < w; x++)
{
for (int y = 0; y < h / 2; y++)
input_data[(y*w + x)*n + 3] = input_data[(y*w + x)*n + 0];
}
stbi_write_png("test-output/premul-original.png", w, h, n, input_data, 0);
int new_w = (int)(w * .5);
int new_h = (int)(h * .5);
@ -302,14 +305,19 @@ void test_premul(const char* file)
stbr_resize_advanced(input_data, w, h, 0, output_data, new_w, new_h, 0, 0, 0, 1, 1, n, 3, STBR_TYPE_UINT8, STBR_FILTER_CATMULLROM, STBR_EDGE_CLAMP, STBR_COLORSPACE_SRGB, tempmem, tempmem_size);
free(tempmem);
stbi_image_free(input_data);
char output[200];
sprintf(output, "test-output/premul-%s", file);
stbi_write_png(output, new_w, new_h, n, output_data, 0);
stbr_resize_advanced(input_data, w, h, 0, output_data, new_w, new_h, 0, 0, 0, 1, 1, n, 0, STBR_TYPE_UINT8, STBR_FILTER_CATMULLROM, STBR_EDGE_CLAMP, STBR_COLORSPACE_SRGB, tempmem, tempmem_size);
sprintf(output, "test-output/nopremul-%s", file);
stbi_write_png(output, new_w, new_h, n, output_data, 0);
free(tempmem);
stbi_image_free(input_data);
free(output_data);
}