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util: add SMPTE pattern support for C1 format 

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@linux-m68k.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
---
Dithering example at https://drive.google.com/file/d/1waJczErrIaEKRhBCCU1ynxRG8agpo0Xx/view

v5:
  - Add Reviewed-by,

v4:
  - Replace FILL_COLOR() use by bw_color_lut[],

v3:
  - Add Acked-by,
  - Add Wikipedia link,

v2:
  New.
main
Geert Uytterhoeven 2022-06-30 18:14:04 +02:00
parent 15c6657617
commit 6b9b462729
1 changed files with 171 additions and 3 deletions
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174
tests/util/pattern.c
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@ -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: