23     if(grad == NULL || grad->filled) return;  in lv_dither_none()
25         grad->map[i] = lv_color_hex(grad->hmap[i].full);  in lv_dither_none()
27     grad->filled = 1;  in lv_dither_none()
49 …3. It means that a pixel i,j only depends on the value of a pixel i-7, j-7 to i,j and no other one.  in lv_dither_ordered_hor()
54         int8_t factor = dither_ordered_threshold_matrix[(y & 7) * 8 + ((j) & 7)] - 32;  in lv_dither_ordered_hor()
55         lv_color32_t tmp = grad->hmap[LV_CLAMP(0, j - 4, grad->size)];  in lv_dither_ordered_hor()
61         grad->map[j] = lv_color_hex(t.full);  in lv_dither_ordered_hor()
72 …3. It means that a pixel i,j only depends on the value of a pixel i-7, j-7 to i,j and no other one.  in lv_dither_ordered_ver()
76     lv_color32_t tmp = grad->hmap[LV_CLAMP(0, y - 4, grad->size)];  in lv_dither_ordered_ver()
80         int8_t factor = dither_ordered_threshold_matrix[(y & 7) * 8 + ((j + x) & 7)] - 32;  in lv_dither_ordered_ver()
86         grad->map[j] = lv_color_hex(t.full);  in lv_dither_ordered_ver()
90     for(; j < w - 8; j += 8) {  in lv_dither_ordered_ver()
91         lv_memcpy(grad->map + j, grad->map, 8 * sizeof(*grad->map));  in lv_dither_ordered_ver()
95         grad->map[j] = grad->map[j & 7];  in lv_dither_ordered_ver()
110         Can be implemented as:            x       (x<<3 - x)  in lv_dither_err_diff_hor()
111                               (x<<2 - x) (x<<2+x)   x  in lv_dither_err_diff_hor()
114 #define FS_COMPUTE_ERROR(e) { coef[0] = (e<<3) - e; coef[1] = (e<<2) - e; coef[2] = (e<<2) + e; coe…  in lv_dither_err_diff_hor()
116 …q) { lv_color32_t u; u.full = lv_color_to32(q); e.r = (int8_t)(t.ch.red - u.ch.red); e.g = (int8_t…  in lv_dither_err_diff_hor()  argument
119     grad->map[0] = lv_color_hex(grad->hmap[0].full);  in lv_dither_err_diff_hor()
120     for(lv_coord_t x = 1; x < grad->size - 1; x++) {  in lv_dither_err_diff_hor()
121         lv_color32_t t = grad->hmap[x];  in lv_dither_err_diff_hor()
122         lv_color_t q;  in lv_dither_err_diff_hor()  local
125         next_l = grad->error_acc[x + 1];  in lv_dither_err_diff_hor()
127         q = lv_color_hex(t.full);  in lv_dither_err_diff_hor()
129         FS_QUANT_ERROR(error, t, q);  in lv_dither_err_diff_hor()
133         grad->error_acc[x - 1].r += coef[1] >> 4;  in lv_dither_err_diff_hor()
134         grad->error_acc[x].r     += coef[2] >> 4;  in lv_dither_err_diff_hor()
135         grad->error_acc[x + 1].r = coef[3] >> 4;  in lv_dither_err_diff_hor()
139         grad->error_acc[x - 1].g += coef[1] >> 4;  in lv_dither_err_diff_hor()
140         grad->error_acc[x].g     += coef[2] >> 4;  in lv_dither_err_diff_hor()
141         grad->error_acc[x + 1].g = coef[3] >> 4;  in lv_dither_err_diff_hor()
145         grad->error_acc[x - 1].b += coef[1] >> 4;  in lv_dither_err_diff_hor()
146         grad->error_acc[x].b     += coef[2] >> 4;  in lv_dither_err_diff_hor()
147         grad->error_acc[x + 1].b = coef[3] >> 4;  in lv_dither_err_diff_hor()
149         grad->map[x] = q;  in lv_dither_err_diff_hor()
151     grad->map[grad->size - 1] = lv_color_hex(grad->hmap[grad->size - 1].full);  in lv_dither_err_diff_hor()
157 …Since the given hi-resolution gradient (in src) is vertical, the Floyd Steinberg algorithm pass ne…  in lv_dither_err_diff_ver()
166            e(i,j) = 1/16 * [ e(i-1,j) * 5 + e(i-1,j+1) * 3 + e(i-1,j-1) * 1 + e(i,j-1) * 7]  in lv_dither_err_diff_ver()
172        Let's remove it and re-dispatch the error factor accordingly so they stays normalized:  in lv_dither_err_diff_ver()
173            e(i,j) ~= 1/16 * [ e(i-1,j) * 6 + e(i-1,j-1) * 1 + e(i,j-1) * 9]  in lv_dither_err_diff_ver()
182     lv_scolor24_t next_px_err, prev_l = grad->error_acc[0];  in lv_dither_err_diff_ver()
185         grad->map[0] = lv_color_hex(grad->hmap[y].full);  in lv_dither_err_diff_ver()
186         FS_QUANT_ERROR(next_px_err, grad->hmap[y], grad->map[0]);  in lv_dither_err_diff_ver()
189         lv_color_t tmp = lv_color_hex(grad->hmap[y].full);  in lv_dither_err_diff_ver()
190         lv_color32_t t = grad->hmap[y];  in lv_dither_err_diff_ver()
191         FS_QUANT_ERROR(next_px_err, grad->hmap[y], tmp);  in lv_dither_err_diff_ver()
192         FS_COMPONENTS3(t, +, next_px_err, 6, prev_l, 1, grad->error_acc[0], 9);  in lv_dither_err_diff_ver()
193         grad->map[0] = lv_color_hex(t.full);  in lv_dither_err_diff_ver()
197         lv_color32_t t = grad->hmap[y];  in lv_dither_err_diff_ver()
198         lv_color_t q;  in lv_dither_err_diff_ver()  local
200         FS_COMPONENTS3(t, +, next_px_err, 6, prev_l, 1, grad->error_acc[x], 9);  in lv_dither_err_diff_ver()
201         prev_l = grad->error_acc[x];  in lv_dither_err_diff_ver()
203         q = lv_color_hex(t.full);  in lv_dither_err_diff_ver()
204         FS_QUANT_ERROR(next_px_err, t, q);  in lv_dither_err_diff_ver()
206         grad->error_acc[x] = next_px_err;  in lv_dither_err_diff_ver()
207         grad->map[x] = q;  in lv_dither_err_diff_ver()