diff --git a/stb_resample.h b/stb_resample.h index 5c3e9c8..0ecf7a4 100644 --- a/stb_resample.h +++ b/stb_resample.h @@ -152,10 +152,12 @@ typedef struct float support; } stbr__filter_info; +// When upsampling, the contributors are which source texels contribute. +// When downsampling, the contributors are which destination texels are contributed to. typedef struct { - int n0; // First contributing source texel - int n1; // Last contributing source texel + int n0; // First contributing texel + int n1; // Last contributing texel } stbr__contributors; typedef struct @@ -177,6 +179,7 @@ typedef struct int total_coefficients; int kernel_texel_width; + int total_horizontal_contributors; stbr__contributors* horizontal_contributors; float* horizontal_coefficients; @@ -195,7 +198,18 @@ typedef struct } stbr__info; -float stbr__filter_nearest(float x) +static stbr_inline int stbr__min(int a, int b) +{ + return a < b ? a : b; +} + +static stbr_inline int stbr__max(int a, int b) +{ + return a > b ? a : b; +} + + +static float stbr__filter_nearest(float x) { if (fabs(x) <= 0.5) return 1; @@ -203,31 +217,29 @@ float stbr__filter_nearest(float x) return 0; } -stbr__filter_info stbr__filter_info_table[] = { +static stbr__filter_info stbr__filter_info_table[] = { { NULL, 0.0f }, { stbr__filter_nearest, 0.5f }, }; // This is the maximum number of input samples that can affect an output sample // with the given filter -int stbr__get_filter_texel_width(stbr_filter filter, int upsample) +stbr_inline static int stbr__get_filter_texel_width(stbr_filter filter) { - STBR_UNIMPLEMENTED(!upsample); - STBR_ASSERT(filter != 0); STBR_ASSERT(filter < STBR_ARRAY_SIZE(stbr__filter_info_table)); return (int)ceil(stbr__filter_info_table[filter].support * 2); } -int stbr__get_total_coefficients(stbr_filter filter, int input_w, int output_w) +stbr_inline static int stbr__get_total_coefficients(stbr_filter filter, int input_w, int output_w) { - return output_w * stbr__get_filter_texel_width(filter, output_w > input_w ? 1 : 0); + return stbr__max(output_w, input_w) * stbr__get_filter_texel_width(filter); } stbr_inline static stbr__contributors* stbr__get_contributor(stbr__info* stbr_info, int n) { - STBR_DEBUG_ASSERT(n >= 0 && n < stbr_info->output_w); + STBR_DEBUG_ASSERT(n >= 0 && n < stbr_info->total_horizontal_contributors); return &stbr_info->horizontal_contributors[n]; } @@ -237,9 +249,8 @@ stbr_inline static float* stbr__get_coefficient(stbr__info* stbr_info, int n, in } // What input texels contribute to this output texel? -static void stbr__calculate_sample_range(int n, float out_filter_radius, float scale_ratio, int* in_first_texel, int* in_last_texel, float* in_center_of_out) +static void stbr__calculate_sample_range_upsample(int n, float out_filter_radius, float scale_ratio, int* in_first_texel, int* in_last_texel, float* in_center_of_out) { - // What input texels contribute to this output texel? float out_texel_center = (float)n + 0.5f; float out_texel_influence_lowerbound = out_texel_center - out_filter_radius; float out_texel_influence_upperbound = out_texel_center + out_filter_radius; @@ -252,7 +263,22 @@ static void stbr__calculate_sample_range(int n, float out_filter_radius, float s *in_last_texel = (int)(floor(in_texel_influence_upperbound - 0.5)); } -static void stbr__calculate_coefficients(stbr__info* stbr_info, int in_first_texel, int in_last_texel, float in_center_of_out, int n, stbr__contributors* contributor, float* coefficient_group) +// What output texels does this input texel contribute to? +static void stbr__calculate_sample_range_downsample(int n, float in_pixels_radius, float scale_ratio, int* out_first_texel, int* out_last_texel, float* out_center_of_in) +{ + float in_texel_center = (float)n + 0.5f; + float in_texel_influence_lowerbound = in_texel_center - in_pixels_radius; + float in_texel_influence_upperbound = in_texel_center + in_pixels_radius; + + float out_texel_influence_lowerbound = in_texel_influence_lowerbound * scale_ratio; + float out_texel_influence_upperbound = in_texel_influence_upperbound * scale_ratio; + + *out_center_of_in = in_texel_center * scale_ratio; + *out_last_texel = (int)(floor(out_texel_influence_lowerbound + 0.5)); + *out_first_texel = (int)(floor(out_texel_influence_upperbound - 0.5)); +} + +static void stbr__calculate_coefficients_upsample(stbr__info* stbr_info, int in_first_texel, int in_last_texel, float in_center_of_out, int n, stbr__contributors* contributor, float* coefficient_group) { int i; float total_filter = 0; @@ -260,7 +286,7 @@ static void stbr__calculate_coefficients(stbr__info* stbr_info, int in_first_tex STBR_DEBUG_ASSERT(in_last_texel - in_first_texel <= stbr_info->kernel_texel_width); STBR_DEBUG_ASSERT(in_first_texel >= 0); - STBR_DEBUG_ASSERT(in_last_texel < stbr_info->input_w); + STBR_DEBUG_ASSERT(in_last_texel < stbr_info->total_horizontal_contributors); contributor->n0 = in_first_texel; contributor->n1 = in_last_texel; @@ -281,6 +307,26 @@ static void stbr__calculate_coefficients(stbr__info* stbr_info, int in_first_tex coefficient_group[i] *= filter_scale; } +static void stbr__calculate_coefficients_downsample(stbr__info* stbr_info, int out_first_texel, int out_last_texel, float out_center_of_in, int n, stbr__contributors* contributor, float* coefficient_group) +{ + int i; + + float scale_ratio = (float)stbr_info->output_w / stbr_info->input_w; + + STBR_DEBUG_ASSERT(out_last_texel - out_first_texel <= stbr_info->kernel_texel_width); + STBR_DEBUG_ASSERT(out_first_texel >= 0); + STBR_DEBUG_ASSERT(out_last_texel < stbr_info->total_horizontal_contributors); + + contributor->n0 = out_first_texel; + contributor->n1 = out_last_texel; + + for (i = 0; i <= out_last_texel - out_first_texel; i++) + { + float in_texel_center = (float)(i + out_first_texel) + 0.5f; + coefficient_group[i] = stbr__filter_info_table[stbr_info->filter].kernel(out_center_of_in - in_texel_center) * scale_ratio; + } +} + // Each scan line uses the same kernel values so we should calculate the kernel // values once and then we can use them for every scan line. static void stbr__calculate_horizontal_filters(stbr__info* stbr_info) @@ -288,18 +334,37 @@ static void stbr__calculate_horizontal_filters(stbr__info* stbr_info) int n; float scale_ratio = (float)stbr_info->output_w / stbr_info->input_w; - float out_pixels_radius = stbr__filter_info_table[stbr_info->filter].support * scale_ratio; + int total_contributors = stbr_info->total_horizontal_contributors; - STBR_UNIMPLEMENTED(stbr_info->output_w < stbr_info->input_w); - - for (n = 0; n < stbr_info->output_w; n++) + if (stbr_info->output_w > stbr_info->input_w) { - float in_center_of_out; // Center of the current out texel in the in texel space - int in_first_texel, in_last_texel; + float out_pixels_radius = stbr__filter_info_table[stbr_info->filter].support * scale_ratio; - stbr__calculate_sample_range(n, out_pixels_radius, scale_ratio, &in_first_texel, &in_last_texel, &in_center_of_out); + // Looping through out texels + for (n = 0; n < total_contributors; n++) + { + float in_center_of_out; // Center of the current out texel in the in texel space + int in_first_texel, in_last_texel; - stbr__calculate_coefficients(stbr_info, in_first_texel, in_last_texel, in_center_of_out, n, stbr__get_contributor(stbr_info, n), stbr__get_coefficient(stbr_info, n, 0)); + stbr__calculate_sample_range_upsample(n, out_pixels_radius, scale_ratio, &in_first_texel, &in_last_texel, &in_center_of_out); + + stbr__calculate_coefficients_upsample(stbr_info, in_first_texel, in_last_texel, in_center_of_out, n, stbr__get_contributor(stbr_info, n), stbr__get_coefficient(stbr_info, n, 0)); + } + } + else + { + float in_pixels_radius = stbr__filter_info_table[stbr_info->filter].support / scale_ratio; + + // Looping through in texels + for (n = 0; n < total_contributors; n++) + { + float out_center_of_in; // Center of the current out texel in the in texel space + int out_first_texel, out_last_texel; + + stbr__calculate_sample_range_downsample(n, in_pixels_radius, scale_ratio, &out_first_texel, &out_last_texel, &out_center_of_in); + + stbr__calculate_coefficients_downsample(stbr_info, out_first_texel, out_last_texel, out_center_of_in, n, stbr__get_contributor(stbr_info, n), stbr__get_coefficient(stbr_info, n, 0)); + } } } @@ -343,6 +408,7 @@ static float* stbr__get_ring_buffer_index(float* ring_buffer, int index, int rin static void stbr__resample_horizontal(stbr__info* stbr_info, int n) { + STBR_UNIMPLEMENTED(stbr_info->output_w < stbr_info->input_w); int x, k, c; int output_w = stbr_info->output_w; int kernel_texel_width = stbr_info->kernel_texel_width; @@ -420,6 +486,7 @@ static float* stbr__get_ring_buffer_scanline(int get_scanline, float* ring_buffe static void stbr__resample_vertical(stbr__info* stbr_info, int n, int in_first_scanline, int in_last_scanline, float in_center_of_out) { + STBR_UNIMPLEMENTED(stbr_info->output_w < stbr_info->input_w); int x, k, c; int output_w = stbr_info->output_w; stbr__contributors* vertical_contributors = &stbr_info->vertical_contributors; @@ -437,7 +504,7 @@ static void stbr__resample_vertical(stbr__info* stbr_info, int n, int in_first_s STBR_UNIMPLEMENTED(stbr_info->type != STBR_TYPE_UINT8); - stbr__calculate_coefficients(stbr_info, in_first_scanline, in_last_scanline, in_center_of_out, n, vertical_contributors, vertical_coefficients); + STBR_UNIMPLEMENTED("stbr__calculate_coefficients(stbr_info, in_first_scanline, in_last_scanline, in_center_of_out, n, vertical_contributors, vertical_coefficients)"); int n0 = vertical_contributors->n0; int n1 = vertical_contributors->n1; @@ -524,13 +591,14 @@ STBRDEF int stbr_resize_arbitrary(const void* input_data, int input_w, int input stbr_info->filter = filter; stbr_info->total_coefficients = stbr__get_total_coefficients(filter, input_w, output_w); - stbr_info->kernel_texel_width = stbr__get_filter_texel_width(filter, output_w > input_w ? 1 : 0); + stbr_info->kernel_texel_width = stbr__get_filter_texel_width(filter); stbr_info->ring_buffer_length = output_w * channels * sizeof(float); + stbr_info->total_horizontal_contributors = stbr__max(input_w, output_w); #define STBR__NEXT_MEMPTR(current, old, newtype) (newtype*)(((unsigned char*)current) + old) stbr_info->horizontal_contributors = STBR__NEXT_MEMPTR(stbr_info, sizeof(stbr__info), stbr__contributors); - stbr_info->horizontal_coefficients = STBR__NEXT_MEMPTR(stbr_info->horizontal_contributors, output_w * sizeof(stbr__contributors), float); + stbr_info->horizontal_coefficients = STBR__NEXT_MEMPTR(stbr_info->horizontal_contributors, stbr_info->total_horizontal_contributors * sizeof(stbr__contributors), float); stbr_info->vertical_coefficients = STBR__NEXT_MEMPTR(stbr_info->horizontal_coefficients, stbr_info->total_coefficients * sizeof(float), float); stbr_info->decode_buffer = STBR__NEXT_MEMPTR(stbr_info->vertical_coefficients, stbr_info->kernel_texel_width * sizeof(float), float); stbr_info->ring_buffer = STBR__NEXT_MEMPTR(stbr_info->decode_buffer, input_w * channels * sizeof(float), float); @@ -548,10 +616,10 @@ STBRDEF int stbr_resize_arbitrary(const void* input_data, int input_w, int input for (y = 0; y < output_h; y++) { - float in_center_of_out; // Center of the current out scanline in the in scanline space - int in_first_scanline, in_last_scanline; + float in_center_of_out = 0; // Center of the current out scanline in the in scanline space + int in_first_scanline = 0, in_last_scanline = 0; - stbr__calculate_sample_range(y, out_scanlines_radius, scale_ratio, &in_first_scanline, &in_last_scanline, &in_center_of_out); + STBR_UNIMPLEMENTED("stbr__calculate_sample_range(y, out_scanlines_radius, scale_ratio, &in_first_scanline, &in_last_scanline, &in_center_of_out)"); STBR_DEBUG_ASSERT(in_last_scanline - in_first_scanline <= stbr_info->kernel_texel_width); STBR_DEBUG_ASSERT(in_first_scanline >= 0); @@ -605,10 +673,10 @@ STBRDEF stbr_size_t stbr_calculate_memory(int input_w, int input_h, int input_st int info_size = sizeof(stbr__info); int decode_buffer_size = input_w * channels * sizeof(float); - int contributors_size = output_w * sizeof(stbr__contributors); + int contributors_size = stbr__max(output_w, input_w) * sizeof(stbr__contributors); int horizontal_coefficients_size = stbr__get_total_coefficients(filter, input_w, output_w) * sizeof(float); - int vertical_coefficients_size = stbr__get_filter_texel_width(filter, output_w > input_w ? 1 : 0) * sizeof(float); - int ring_buffer_size = output_w * channels * sizeof(float) * stbr__get_filter_texel_width(filter, output_w > input_w ? 1 : 0); + int vertical_coefficients_size = stbr__get_filter_texel_width(filter) * sizeof(float); + int ring_buffer_size = output_w * channels * sizeof(float) * stbr__get_filter_texel_width(filter); int encode_buffer_size = channels * sizeof(float); return info_size + decode_buffer_size + contributors_size + horizontal_coefficients_size + vertical_coefficients_size + ring_buffer_size + encode_buffer_size; diff --git a/tests/resample_test.cpp b/tests/resample_test.cpp index 2ee2ffb..f47068e 100644 --- a/tests/resample_test.cpp +++ b/tests/resample_test.cpp @@ -39,8 +39,8 @@ int main(int argc, char** argv) return 1; } - out_w = 1024; - out_h = 1024; + out_w = 256; + out_h = 256; out_stride = (out_w + 10) * n; output_data = (unsigned char*)malloc(out_stride * out_h);