Add support for drawing the SMPTE pattern in a buffer using the C1 indexed format. As only two colors are available, the pattern is drawn in black and white, using Floyd-Steinberg dithering[1]. [1] https://en.wikipedia.org/wiki/Floyd%E2%80%93Steinberg_dithering Signed-off-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> Acked-by: Sam Ravnborg <sam@xxxxxxxxxxxx> --- Dithering example at https://drive.google.com/file/d/1waJczErrIaEKRhBCCU1ynxRG8agpo0Xx/view v4: - Replace FILL_COLOR() use by bw_color_lut[], v3: - Add Acked-by, - Add Wikipedia link, v2: New. --- tests/util/pattern.c | 174 ++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 171 insertions(+), 3 deletions(-) diff --git a/tests/util/pattern.c b/tests/util/pattern.c index 17074265dc60033c..2362555356e0dd71 100644 --- a/tests/util/pattern.c +++ b/tests/util/pattern.c @@ -654,6 +654,11 @@ static unsigned int smpte_bottom[8] = { #define EXPAND_COLOR(r, g, b) { (r) * 0x101, (g) * 0x101, (b) * 0x101 } +static const struct drm_color_lut bw_color_lut[] = { + EXPAND_COLOR( 0, 0, 0), /* black */ + EXPAND_COLOR(255, 255, 255), /* white */ +}; + static const struct drm_color_lut smpte_color_lut[] = { [SMPTE_COLOR_GREY] = EXPAND_COLOR(192, 192, 192), [SMPTE_COLOR_YELLOW] = EXPAND_COLOR(192, 192, 0), @@ -672,6 +677,164 @@ static const struct drm_color_lut smpte_color_lut[] = { #undef EXPAND_COLOR +/* + * Floyd-Steinberg dithering + */ + +struct fsd { + unsigned int width; + unsigned int x; + unsigned int i; + int red; + int green; + int blue; + int error[]; +}; + +static struct fsd *fsd_alloc(unsigned int width) +{ + unsigned int n = 3 * (width + 1); + struct fsd *fsd = malloc(sizeof(*fsd) + n * sizeof(fsd->error[0])); + + fsd->width = width; + fsd->x = 0; + fsd->i = 0; + memset(fsd->error, 0, n * sizeof(fsd->error[0])); + + return fsd; +} + +static inline int clamp(int val, int min, int max) +{ + if (val < min) + return min; + if (val > max) + return max; + return val; +} + +static void fsd_dither(struct fsd *fsd, struct drm_color_lut *color) +{ + unsigned int i = fsd->i; + + fsd->red = (int)color->red + (fsd->error[3 * i] + 8) / 16; + fsd->green = (int)color->green + (fsd->error[3 * i + 1] + 8) / 16; + fsd->blue = (int)color->blue + (fsd->error[3 * i + 2] + 8) / 16; + + color->red = clamp(fsd->red, 0, 65535); + color->green = clamp(fsd->green, 0, 65535); + color->blue = clamp(fsd->blue, 0, 65535); +} + +static void fsd_update(struct fsd *fsd, const struct drm_color_lut *actual) +{ + int error_red = fsd->red - (int)actual->red; + int error_green = fsd->green - (int)actual->green; + int error_blue = fsd->blue - (int)actual->blue; + unsigned int width = fsd->width; + unsigned int i = fsd->i, j; + unsigned int n = width + 1; + + /* Distribute errors over neighboring pixels */ + if (fsd->x == width - 1) { + /* Last pixel on this scanline */ + /* South East: initialize to zero */ + fsd->error[3 * i] = 0; + fsd->error[3 * i + 1] = 0; + fsd->error[3 * i + 2] = 0; + } else { + /* East: accumulate error */ + j = (i + 1) % n; + fsd->error[3 * j] += 7 * error_red; + fsd->error[3 * j + 1] += 7 * error_green; + fsd->error[3 * j + 2] += 7 * error_blue; + + /* South East: initial error */ + fsd->error[3 * i] = error_red; + fsd->error[3 * i + 1] = error_green; + fsd->error[3 * i + 2] = error_blue; + } + /* South West: accumulate error */ + j = (i + width - 1) % n; + fsd->error[3 * j] += 3 * error_red; + fsd->error[3 * j + 1] += 3 * error_green; + fsd->error[3 * j + 2] += 3 * error_blue; + + /* South: accumulate error */ + j = (i + width) % n; + fsd->error[3 * j] += 5 * error_red; + fsd->error[3 * j + 1] += 5 * error_green; + fsd->error[3 * j + 2] += 5 * error_blue; + + fsd->x = (fsd->x + 1) % width; + fsd->i = (fsd->i + 1) % n; +} + +static void write_pixel_1(uint8_t *mem, unsigned int x, unsigned int pixel) +{ + unsigned int shift = 7 - (x & 7); + unsigned int mask = 1U << shift; + + mem[x / 8] = (mem[x / 8] & ~mask) | ((pixel << shift) & mask); +} + +static void write_color_1(struct fsd *fsd, uint8_t *mem, unsigned int x, + unsigned int index) +{ + struct drm_color_lut color = smpte_color_lut[index]; + unsigned int pixel; + + fsd_dither(fsd, &color); + + /* ITU BT.601: Y = 0.299 R + 0.587 G + 0.114 B */ + if (3 * color.red + 6 * color.green + color.blue >= 10 * 32768) { + pixel = 1; + color.red = color.green = color.blue = 65535; + } else { + pixel = 0; + color.red = color.green = color.blue = 0; + } + + fsd_update(fsd, &color); + + write_pixel_1(mem, x, pixel); +} + +static void fill_smpte_c1(void *mem, unsigned int width, unsigned int height, + unsigned int stride) +{ + struct fsd *fsd = fsd_alloc(width); + unsigned int x; + unsigned int y; + + for (y = 0; y < height * 6 / 9; ++y) { + for (x = 0; x < width; ++x) + write_color_1(fsd, mem, x, smpte_top[x * 7 / width]); + mem += stride; + } + + for (; y < height * 7 / 9; ++y) { + for (x = 0; x < width; ++x) + write_color_1(fsd, mem, x, smpte_middle[x * 7 / width]); + mem += stride; + } + + for (; y < height; ++y) { + for (x = 0; x < width * 5 / 7; ++x) + write_color_1(fsd, mem, x, + smpte_bottom[x * 4 / (width * 5 / 7)]); + for (; x < width * 6 / 7; ++x) + write_color_1(fsd, mem, x, + smpte_bottom[(x - width * 5 / 7) * 3 / + (width / 7) + 4]); + for (; x < width; ++x) + write_color_1(fsd, mem, x, smpte_bottom[7]); + mem += stride; + } + + free(fsd); +} + static void write_pixel_4(uint8_t *mem, unsigned int x, unsigned int pixel) { if (x & 1) @@ -746,14 +909,17 @@ static void fill_smpte_c8(void *mem, unsigned int width, unsigned int height, void util_smpte_fill_lut(unsigned int ncolors, struct drm_color_lut *lut) { - if (ncolors < ARRAY_SIZE(smpte_color_lut)) { + if (ncolors < ARRAY_SIZE(bw_color_lut)) { printf("Error: lut too small: %u < %zu\n", ncolors, - ARRAY_SIZE(smpte_color_lut)); + ARRAY_SIZE(bw_color_lut)); return; } memset(lut, 0, ncolors * sizeof(struct drm_color_lut)); - memcpy(lut, smpte_color_lut, sizeof(smpte_color_lut)); + if (ncolors < ARRAY_SIZE(smpte_color_lut)) + memcpy(lut, bw_color_lut, sizeof(bw_color_lut)); + else + memcpy(lut, smpte_color_lut, sizeof(smpte_color_lut)); } static void fill_smpte(const struct util_format_info *info, void *planes[3], @@ -763,6 +929,8 @@ static void fill_smpte(const struct util_format_info *info, void *planes[3], unsigned char *u, *v; switch (info->format) { + case DRM_FORMAT_C1: + return fill_smpte_c1(planes[0], width, height, stride); case DRM_FORMAT_C4: return fill_smpte_c4(planes[0], width, height, stride); case DRM_FORMAT_C8: -- 2.34.1
