diff options
Diffstat (limited to 'src/sstv.c')
| -rw-r--r-- | src/sstv.c | 122 |
1 files changed, 122 insertions, 0 deletions
@@ -6,6 +6,20 @@ */ #include "libsstv.h" +#include "sstv.h" + +/* + * Colorspace conversion macros + * Kudos to Leszek Szary + * https://stackoverflow.com/questions/1737726/how-to-perform-rgb-yuv-conversion-in-c-c + */ +#define CLIP(X) ( (X) > 255 ? 255 : (X) < 0 ? 0 : X) +#define CRGB2Y(R, G, B) CLIP((19595 * R + 38470 * G + 7471 * B ) >> 16) +#define CRGB2Cb(R, G, B) CLIP((36962 * (B - CLIP((19595 * R + 38470 * G + 7471 * B ) >> 16) ) >> 16) + 128) +#define CRGB2Cr(R, G, B) CLIP((46727 * (R - CLIP((19595 * R + 38470 * G + 7471 * B ) >> 16) ) >> 16) + 128) +#define CYCbCr2R(Y, Cb, Cr) CLIP( Y + ( 91881 * Cr >> 16 ) - 179 ) +#define CYCbCr2G(Y, Cb, Cr) CLIP( Y - (( 22544 * Cb + 46793 * Cr ) >> 16) + 135) +#define CYCbCr2B(Y, Cb, Cr) CLIP( Y + (116129 * Cb >> 16 ) - 226 ) sstv_malloc_t sstv_malloc_user = NULL; sstv_free_t sstv_free_user = NULL; @@ -25,6 +39,114 @@ sstv_init(sstv_malloc_t alloc_func, sstv_free_t dealloc_func) } sstv_error_t +sstv_convert_image(sstv_image_t *img, sstv_image_format_t format) +{ + if (!img) { + return SSTV_BAD_PARAMETER; + } + + if (img->format == format) { + /* no conversion necessary */ + return SSTV_OK; + } + + if (img->format == SSTV_FORMAT_Y) { + /* can't convert from grayscale to anything */ + return SSTV_UNSUPPORTED_CONVERSION; + } + + /* perform conversion */ + uint32_t num_px = img->width * img->height; + uint32_t i; + switch (format) { + case SSTV_FORMAT_Y: + { + switch (img->format) { + case SSTV_FORMAT_Y: + /* identity, do nothing */ + break; + + case SSTV_FORMAT_YCBCR: + /* condense first channel */ + for (i = 0; i < num_px; i ++) { + img->buffer[i] = img->buffer[i * 3]; + } + break; + + case SSTV_FORMAT_RGB: + /* extract Y from RGB and set as first channel */ + for (i = 0; i < num_px; i ++) { + int32_t r = img->buffer[i * 3 + 0]; + int32_t g = img->buffer[i * 3 + 1]; + int32_t b = img->buffer[i * 3 + 2]; + img->buffer[i] = CRGB2Y(r, g, b); + } + break; + + default: + return SSTV_UNSUPPORTED_CONVERSION; + } + } + break; + + case SSTV_FORMAT_YCBCR: + { + switch (img->format) { + case SSTV_FORMAT_YCBCR: + /* identity, do nothing */ + break; + + case SSTV_FORMAT_RGB: + for (i = 0; i < num_px; i ++) { + int32_t r = img->buffer[i * 3 + 0]; + int32_t g = img->buffer[i * 3 + 1]; + int32_t b = img->buffer[i * 3 + 2]; + img->buffer[i * 3 + 0] = CRGB2Y(r, g, b); + img->buffer[i * 3 + 1] = CRGB2Cb(r, g, b); + img->buffer[i * 3 + 2] = CRGB2Cr(r, g, b); + } + break; + + default: + return SSTV_UNSUPPORTED_CONVERSION; + } + } + break; + + case SSTV_FORMAT_RGB: + { + switch (img->format) { + case SSTV_FORMAT_YCBCR: + for (i = 0; i < num_px; i ++) { + int32_t y = img->buffer[i * 3 + 0]; + int32_t b = img->buffer[i * 3 + 1]; + int32_t r = img->buffer[i * 3 + 2]; + img->buffer[i * 3 + 0] = CYCbCr2R(y, b ,r); + img->buffer[i * 3 + 1] = CYCbCr2G(y, b ,r); + img->buffer[i * 3 + 2] = CYCbCr2B(y, b ,r); + } + break; + + case SSTV_FORMAT_RGB: + /* identity, do nothing */ + break; + + default: + return SSTV_UNSUPPORTED_CONVERSION; + } + } + break; + + default: + return SSTV_BAD_FORMAT; + } + + /* all ok */ + img->format = format; + return SSTV_OK; +} + +sstv_error_t sstv_get_mode_image_props(sstv_mode_t mode, size_t *width, size_t *height, sstv_image_format_t *format) { switch (mode) { |