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stb
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Add catmull rom filter. Also, move the debug asserts for values <= 1 to the very end of the process. This will make these bugs a lot harder to find, but because some filter kernels have negative values it's possible for the buffers to have values > 1 up until the point where it's converted back to an int.

pull/32/head
Jorge Rodriguez 2014-07-26 14:52:28 -07:00
parent 12acf87eec
commit 69af963c42
1 changed files with 28 additions and 22 deletions
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50
stb_resample.h
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@ -30,6 +30,7 @@ typedef enum
STBR_FILTER_NEAREST = 1,
STBR_FILTER_BILINEAR = 2,
STBR_FILTER_BICUBIC = 3, // A cubic b spline
STBR_FILTER_CATMULLROM = 4,
} stbr_filter;
typedef enum
@ -245,11 +246,26 @@ static float stbr__filter_bicubic(float x)
return (0.0f);
}
static float stbr__filter_catmullrom(float x)
{
x = (float)fabs(x);
float xx = x*x;
if (x < 1.0f)
return 1.5f * (x * xx) - 2.5f * xx + 1;
else if (x < 2.0f)
return -0.5f * (x * xx) + 2.5f * xx - 4 * x + 2;
return (0.0f);
}
static stbr__filter_info stbr__filter_info_table[] = {
{ NULL, 0.0f },
{ stbr__filter_nearest, 0.5f },
{ stbr__filter_bilinear, 1.0f },
{ stbr__filter_bicubic, 2.0f },
{ NULL, 0.0f },
{ stbr__filter_nearest, 0.5f },
{ stbr__filter_bilinear, 1.0f },
{ stbr__filter_bicubic, 2.0f },
{ stbr__filter_catmullrom, 2.0f },
};
stbr_inline static int stbr__use_width_upsampling_noinfo(int output_w, int input_w)
@ -515,8 +531,6 @@ static void stbr__output_decode_coefficients_1(float* output_buffer, int out_tex
STBR_DEBUG_ASSERT(channels == 1);
output_buffer[out_texel_index] += input_buffer[input_texel_index] * coefficient;
STBR_DEBUG_ASSERT(output_buffer[out_texel_index] <= 1.001f);
}
static void stbr__output_decode_coefficients_2(float* output_buffer, int out_texel_index, float* input_buffer, int input_texel_index, int channels, float coefficient)
@ -525,9 +539,6 @@ static void stbr__output_decode_coefficients_2(float* output_buffer, int out_tex
output_buffer[out_texel_index ] += input_buffer[input_texel_index ] * coefficient;
output_buffer[out_texel_index + 1] += input_buffer[input_texel_index + 1] * coefficient;
STBR_DEBUG_ASSERT(output_buffer[out_texel_index ] <= 1.001f);
STBR_DEBUG_ASSERT(output_buffer[out_texel_index + 1] <= 1.001f);
}
static void stbr__output_decode_coefficients_3(float* output_buffer, int out_texel_index, float* input_buffer, int input_texel_index, int channels, float coefficient)
@ -537,10 +548,6 @@ static void stbr__output_decode_coefficients_3(float* output_buffer, int out_tex
output_buffer[out_texel_index ] += input_buffer[input_texel_index ] * coefficient;
output_buffer[out_texel_index + 1] += input_buffer[input_texel_index + 1] * coefficient;
output_buffer[out_texel_index + 2] += input_buffer[input_texel_index + 2] * coefficient;
STBR_DEBUG_ASSERT(output_buffer[out_texel_index ] <= 1.001f);
STBR_DEBUG_ASSERT(output_buffer[out_texel_index + 1] <= 1.001f);
STBR_DEBUG_ASSERT(output_buffer[out_texel_index + 2] <= 1.001f);
}
static void stbr__output_decode_coefficients_4(float* output_buffer, int out_texel_index, float* input_buffer, int input_texel_index, int channels, float coefficient)
@ -551,22 +558,13 @@ static void stbr__output_decode_coefficients_4(float* output_buffer, int out_tex
output_buffer[out_texel_index + 1] += input_buffer[input_texel_index + 1] * coefficient;
output_buffer[out_texel_index + 2] += input_buffer[input_texel_index + 2] * coefficient;
output_buffer[out_texel_index + 3] += input_buffer[input_texel_index + 3] * coefficient;
STBR_DEBUG_ASSERT(output_buffer[out_texel_index ] <= 1.001f);
STBR_DEBUG_ASSERT(output_buffer[out_texel_index + 1] <= 1.001f);
STBR_DEBUG_ASSERT(output_buffer[out_texel_index + 2] <= 1.001f);
STBR_DEBUG_ASSERT(output_buffer[out_texel_index + 3] <= 1.001f);
}
static void stbr__output_decode_coefficients_n(float* output_buffer, int out_texel_index, float* input_buffer, int input_texel_index, int channels, float coefficient)
{
int c;
for (c = 0; c < channels; c++)
{
output_buffer[out_texel_index + c] += input_buffer[input_texel_index + c] * coefficient;
STBR_DEBUG_ASSERT(output_buffer[out_texel_index + c] <= 1.001f);
}
}
static stbr__output_decode_coefficients stbr__get_output_decode_coefficients_function(int channels)
@ -751,7 +749,11 @@ static void stbr__resample_vertical_upsample(stbr__info* stbr_info, int n, int i
}
for (c = 0; c < channels; c++)
{
STBR_DEBUG_ASSERT(encode_buffer[c] < 1.0f + 1.0f/255);
((unsigned char*)output_data)[out_texel_index + c] = (unsigned char)(encode_buffer[c] * 255);
}
}
}
@ -885,7 +887,11 @@ static void stbr__empty_ring_buffer(stbr__info* stbr_info, int first_necessary_s
int ring_texel_index = texel_index;
int output_texel_index = output_row + texel_index;
for (c = 0; c < channels; c++)
{
STBR_DEBUG_ASSERT(ring_buffer_entry[ring_texel_index + c] < 1.0f + 1.0f / 255);
((unsigned char*)output_data)[output_texel_index + c] = (unsigned char)(ring_buffer_entry[ring_texel_index + c] * 255);
}
}
}