diff options
Diffstat (limited to 'dither.c')
| -rw-r--r-- | dither.c | 193 |
1 files changed, 0 insertions, 193 deletions
diff --git a/dither.c b/dither.c deleted file mode 100644 index 2eaeb31..0000000 --- a/dither.c +++ /dev/null @@ -1,193 +0,0 @@ -/* - * ordered dither rotines - * - * stolen from The GIMP and trimmed for speed - * - */ - -#include <stdlib.h> -#include "dither.h" - -#define DITHER_LEVEL 8 - -void (*dither_line)(unsigned char *, unsigned char *, int, int); - -static long red_mult, green_mult; -static long red_dither[256]; -static long green_dither[256]; -static long blue_dither[256]; -static long gray_dither[256]; - -typedef unsigned long vector[DITHER_LEVEL]; -typedef vector matrix[DITHER_LEVEL]; - -#if DITHER_LEVEL == 8 -#define DITHER_MASK 7 -static matrix DM = -{ - {0, 32, 8, 40, 2, 34, 10, 42}, - {48, 16, 56, 24, 50, 18, 58, 26}, - {12, 44, 4, 36, 14, 46, 6, 38}, - {60, 28, 52, 20, 62, 30, 54, 22}, - {3, 35, 11, 43, 1, 33, 9, 41}, - {51, 19, 59, 27, 49, 17, 57, 25}, - {15, 47, 7, 39, 13, 45, 5, 37}, - {63, 31, 55, 23, 61, 29, 53, 21} -}; - -#endif - -#if DITHER_LEVEL == 4 -#define DITHER_MASK 3 -static matrix DM = -{ - {0, 8, 2, 10}, - {12, 4, 14, 6}, - {3, 11, 1, 9}, - {15, 7, 13, 5} -}; - -#endif - -void -init_dither(int shades_r, int shades_g, int shades_b, int shades_gray) -{ - int i, j; - unsigned char low_shade, high_shade; - unsigned short index; - float red_colors_per_shade; - float green_colors_per_shade; - float blue_colors_per_shade; - float gray_colors_per_shade; - - red_mult = shades_g * shades_b; - green_mult = shades_b; - - red_colors_per_shade = 256.0 / (shades_r - 1); - green_colors_per_shade = 256.0 / (shades_g - 1); - blue_colors_per_shade = 256.0 / (shades_b - 1); - gray_colors_per_shade = 256.0 / (shades_gray - 1); - - /* this avoids a shift when checking these values */ - for (i = 0; i < DITHER_LEVEL; i++) - for (j = 0; j < DITHER_LEVEL; j++) - DM[i][j] *= 0x10000; - - /* setup arrays containing three bytes of information for red, green, & blue */ - /* the arrays contain : - * 1st byte: low end shade value - * 2nd byte: high end shade value - * 3rd & 4th bytes: ordered dither matrix index - */ - - for (i = 0; i < 256; i++) { - - /* setup the red information */ - { - low_shade = (unsigned char) (i / red_colors_per_shade); - high_shade = low_shade + 1; - - index = (unsigned short) - (((i - low_shade * red_colors_per_shade) / red_colors_per_shade) * - (DITHER_LEVEL * DITHER_LEVEL + 1)); - - low_shade *= red_mult; - high_shade *= red_mult; - - red_dither[i] = (index << 16) + (high_shade << 8) + (low_shade); - } - - /* setup the green information */ - { - low_shade = (unsigned char) (i / green_colors_per_shade); - high_shade = low_shade + 1; - - index = (unsigned short) - (((i - low_shade * green_colors_per_shade) / green_colors_per_shade) * - (DITHER_LEVEL * DITHER_LEVEL + 1)); - - low_shade *= green_mult; - high_shade *= green_mult; - - green_dither[i] = (index << 16) + (high_shade << 8) + (low_shade); - } - - /* setup the blue information */ - { - low_shade = (unsigned char) (i / blue_colors_per_shade); - high_shade = low_shade + 1; - - index = (unsigned short) - (((i - low_shade * blue_colors_per_shade) / blue_colors_per_shade) * - (DITHER_LEVEL * DITHER_LEVEL + 1)); - - blue_dither[i] = (index << 16) + (high_shade << 8) + (low_shade); - } - - /* setup the gray information */ - { - low_shade = (unsigned char) (i / gray_colors_per_shade); - high_shade = low_shade + 1; - - index = (unsigned short) - (((i - low_shade * gray_colors_per_shade) / gray_colors_per_shade) * - (DITHER_LEVEL * DITHER_LEVEL + 1)); - - gray_dither[i] = (index << 16) + (high_shade << 8) + (low_shade); - } - } -} - -void -dither_line_color(unsigned char *src, unsigned char *dest, int y, int width) -{ - register long a, b; - long *ymod, xmod; - - ymod = DM[y & DITHER_MASK]; - - while (width--) { - xmod = width & DITHER_MASK; - - b = red_dither[*(src++)]; - if (ymod[xmod] < b) - b >>= 8; - - a = green_dither[*(src++)]; - if (ymod[xmod] < a) - a >>= 8; - b += a; - - a = blue_dither[*(src++)]; - if (ymod[xmod] < a) - a >>= 8; - b += a; - - *(dest++) = b & 0xff; - } -} - -void -dither_line_gray(unsigned char *src, unsigned char *dest, int y, int width) -{ - long *ymod, xmod; - register long a,g; - - ymod = DM[y & DITHER_MASK]; - - while (width--) { - xmod = width & DITHER_MASK; - -#if 1 - g = (src[0]*3 + src[1]*6 + src[2]) / 10; - a = gray_dither[g]; - src += 3; -#else - a = gray_dither[*(src++)]; -#endif - if (ymod[xmod] < a) - a >>= 8; - - *(dest++) = a & 0xff; - } -} |