djsundog
/
circuitpython
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

dither in x/y, not i/j 

The easiest thing to implement was to use the i/j numbers, but they were not
directly related to image x/y coordinates.  This may slow things down a tiny
little bit, but it looks much better.
This commit is contained in:
Jeff Epler 2021-10-27 16:52:48 -05:00
parent ef4623dfae
commit e733876574
1 changed files with 9 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
shared-module/gifio/GifWriter.c
View File

@ -231,6 +231,7 @@ void shared_module_gifio_gifwriter_add_frame(gifio_gifwriter_t *self, const mp_b
mp_get_index(&mp_type_memoryview, bufinfo->len, MP_OBJ_NEW_SMALL_INT(2 * pixel_count - 1), false);
uint16_t *pixels = bufinfo->buf;
int x = 0, y = 0;
for (int i = 0; i < blocks; i++) {
int block_size = MIN(BLOCK_SIZE, pixel_count);
pixel_count -= block_size;
@ -246,9 +247,14 @@ void shared_module_gifio_gifwriter_add_frame(gifio_gifwriter_t *self, const mp_b
int green = (pixel >> 3) & 0xfc;
int blue = (pixel << 3) & 0xf8;
red = MAX(0, red - rb_bayer[i % 4][j % 4]);
green = MAX(0, green - g_bayer[i % 4][j % 4]);
blue = MAX(0, blue - rb_bayer[i % 4][j % 4]);
red = MAX(0, red - rb_bayer[x % 4][y % 4]);
green = MAX(0, green - g_bayer[x % 4][(y + 2) % 4]);
blue = MAX(0, blue - rb_bayer[(x + 2) % 4][y % 4]);
x++;
if (x == self->width) {
x = 0;
y++;
}
*data++ = ((red >> 1) & 0x60) | ((green >> 3) & 0x1c) | (blue >> 6);
}