@@ -147,31 +147,39 @@ static av_always_inline int diff(const uint32_t a, const uint32_t b)
static void compute_box_stats(PaletteGenContext *s, struct range_box *box)
{
- int rr, gr, br;
+ int avg[3];
+ int64_t er2[3] = {0};
- /* compute the box weight (sum all the weights of the colors in the
- * range) and its boundings */
- uint8_t min[3] = {0xff, 0xff, 0xff};
- uint8_t max[3] = {0x00, 0x00, 0x00};
+ /* Compute average color */
+ uint64_t sr = 0, sg = 0, sb = 0;
box->weight = 0;
for (int i = box->start; i < box->start + box->len; i++) {
const struct color_ref *ref = s->refs[i];
- const uint32_t rgb = ref->color;
- const uint8_t r = rgb >> 16 & 0xff, g = rgb >> 8 & 0xff, b = rgb & 0xff;
- min[0] = FFMIN(r, min[0]), max[0] = FFMAX(r, max[0]);
- min[1] = FFMIN(g, min[1]), max[1] = FFMAX(g, max[1]);
- min[2] = FFMIN(b, min[2]), max[2] = FFMAX(b, max[2]);
+ sr += (ref->color >> 16 & 0xff) * ref->count;
+ sg += (ref->color >> 8 & 0xff) * ref->count;
+ sb += (ref->color & 0xff) * ref->count;
box->weight += ref->count;
}
+ avg[0] = sr / box->weight;
+ avg[1] = sg / box->weight;
+ avg[2] = sb / box->weight;
- /* define the axis to sort by according to the widest range of colors */
- rr = max[0] - min[0];
- gr = max[1] - min[1];
- br = max[2] - min[2];
+ /* Compute squared error of each color channel */
+ for (int i = box->start; i < box->start + box->len; i++) {
+ const struct color_ref *ref = s->refs[i];
+ const int64_t dr = (int)(ref->color >> 16 & 0xff) - avg[0];
+ const int64_t dg = (int)(ref->color >> 8 & 0xff) - avg[1];
+ const int64_t db = (int)(ref->color & 0xff) - avg[2];
+ er2[0] += dr * dr * ref->count;
+ er2[1] += dg * dg * ref->count;
+ er2[2] += db * db * ref->count;
+ }
+
+ /* Define the best axis candidate for cutting the box */
box->major_axis = 1; // pick green by default (the color the eye is the most sensitive to)
- if (br >= rr && br >= gr) box->major_axis = 2;
- if (rr >= gr && rr >= br) box->major_axis = 0;
- if (gr >= rr && gr >= br) box->major_axis = 1; // prefer green again
+ if (er2[2] >= er2[0] && er2[2] >= er2[1]) box->major_axis = 2;
+ if (er2[0] >= er2[1] && er2[0] >= er2[2]) box->major_axis = 0;
+ if (er2[1] >= er2[0] && er2[1] >= er2[2]) box->major_axis = 1; // prefer green again
}
/**
@@ -3,4 +3,4 @@
#codec_id 0: rawvideo
#dimensions 0: 16x16
#sar 0: 1/1
-0, 0, 0, 1, 1024, 0x3395ef5a
+0, 0, 0, 1, 1024, 0x394ee723
@@ -3,4 +3,4 @@
#codec_id 0: rawvideo
#dimensions 0: 16x16
#sar 0: 1/1
-0, 0, 0, 1, 1024, 0x23e072c8
+0, 0, 0, 1, 1024, 0xc54d773d