The split decision is now based on the per-axis variance instead of how wide they are. --- libavfilter/vf_palettegen.c | 61 ++++++++++++++++-------------- tests/ref/fate/filter-palettegen-1 | 2 +- tests/ref/fate/filter-palettegen-2 | 2 +- 3 files changed, 35 insertions(+), 30 deletions(-)
diff --git a/libavfilter/vf_palettegen.c b/libavfilter/vf_palettegen.c index 4c2bcba7f7..2976012512 100644 --- a/libavfilter/vf_palettegen.c +++ b/libavfilter/vf_palettegen.c @@ -45,6 +45,7 @@ struct color_ref { struct range_box { uint32_t color; // average color double variance; // overall variance of the box (how much the colors are spread) + double axis_variance[3]; // axis specific variance int start; // index in PaletteGenContext->refs int len; // number of referenced colors int sorted_by; // whether range of colors is sorted by red (0), green (1) or blue (2) @@ -136,24 +137,29 @@ static int cmp_color(const void *a, const void *b) return FFDIFFSIGN(box1->color , box2->color); } -static av_always_inline float diff(const uint32_t a, const uint32_t b) -{ - const struct Lab lab0 = ff_srgb_u8_to_oklab(a); - const struct Lab lab1 = ff_srgb_u8_to_oklab(b); - const float dL = lab0.L - lab1.L; - const float da = lab0.a - lab1.a; - const float db = lab0.b - lab1.b; - return dL*dL + da*da + db*db; -} - static void compute_box_variance(PaletteGenContext *s, struct range_box *box) { double variance = 0.0; for (int i = 0; i < box->len; i++) { const struct color_ref *ref = s->refs[box->start + i]; - variance += diff(ref->color, box->color) * ref->count; + const struct Lab lab0 = ff_srgb_u8_to_oklab(ref->color); + const struct Lab lab1 = ff_srgb_u8_to_oklab(box->color); + const float dL = lab0.L - lab1.L; + const float da = lab0.a - lab1.a; + const float db = lab0.b - lab1.b; + + variance += (dL*dL + da*da + db*db) * ref->count; + + /* + * No need to normalize the per-axis variances since they are compared + * only locally within the box and thus share the same weight. + */ + box->axis_variance[0] += dL*dL * ref->count; + box->axis_variance[1] += da*da * ref->count; + box->axis_variance[2] += db*db * ref->count; } + /* * The variance is computed as a Mean Squared Error of the distance of the * current color to the box color average, with an important difference: @@ -198,6 +204,7 @@ static int get_next_box_id_to_split(PaletteGenContext *s) } } else { box->variance = -1.0; + memset(box->axis_variance, 0, sizeof(box->axis_variance)); } } return best_box_id; @@ -249,6 +256,8 @@ static void split_box(PaletteGenContext *s, struct range_box *box, int n) new_box->color = get_avg_color(s->refs, new_box); box->variance = -1.0; new_box->variance = -1.0; + memset(box->axis_variance, 0, sizeof(box->axis_variance)); + memset(new_box->axis_variance, 0, sizeof(new_box->axis_variance)); } /** @@ -346,38 +355,34 @@ static AVFrame *get_palette_frame(AVFilterContext *ctx) box->sorted_by = -1; box->color = get_avg_color(s->refs, box); box->variance = -1.0; + memset(box->axis_variance, 0, sizeof(box->axis_variance)); + compute_box_variance(s, box); s->nb_boxes = 1; while (box && box->len > 1) { int i, longest; - double Lr, ar, br; + double Lv, av, bv; uint64_t median, box_weight = 0; /* compute the box weight (sum all the weights of the colors in the - * range) and its boundings */ - float min[3] = {FLT_MAX, FLT_MAX, FLT_MAX}; - float max[3] = {-FLT_MAX, -FLT_MAX, -FLT_MAX}; + * range) */ for (i = box->start; i < box->start + box->len; i++) { const struct color_ref *ref = s->refs[i]; - const struct Lab lab = ref->lab; - min[0] = FFMIN(lab.L, min[0]), max[0] = FFMAX(lab.L, max[0]); - min[1] = FFMIN(lab.a, min[1]), max[1] = FFMAX(lab.a, max[1]); - min[2] = FFMIN(lab.b, min[2]), max[2] = FFMAX(lab.b, max[2]); box_weight += ref->count; } - /* define the axis to sort by according to the widest range of colors */ - Lr = max[0] - min[0]; - ar = max[1] - min[1]; - br = max[2] - min[2]; + /* pick the axis with the biggest variance */ + Lv = box->axis_variance[0]; + av = box->axis_variance[1]; + bv = box->axis_variance[2]; longest = 0; - if (br >= Lr && br >= ar) longest = 2; - if (ar >= Lr && ar >= br) longest = 1; - if (Lr >= ar && Lr >= br) longest = 0; + if (bv >= Lv && bv >= av) longest = 2; + if (av >= Lv && av >= bv) longest = 1; + if (Lv >= av && Lv >= bv) longest = 0; - ff_dlog(ctx, "box #%02X [%6d..%-6d] (%6d) w:%-6"PRIu64" ranges:[%.3f %.3f %.3f] sort by %c (already sorted:%c) ", + ff_dlog(ctx, "box #%02X [%6d..%-6d] (%6d) w:%-6"PRIu64" var:[%.3f %.3f %.3f] sort by %c (already sorted:%c) ", box_id, box->start, box->start + box->len - 1, box->len, box_weight, - Lr, ar, br, "Lab"[longest], box->sorted_by == longest ? 'y':'n'); + Lv, av, bv, "Lab"[longest], box->sorted_by == longest ? 'y':'n'); /* sort the range by its longest axis if it's not already sorted */ if (box->sorted_by != longest) { diff --git a/tests/ref/fate/filter-palettegen-1 b/tests/ref/fate/filter-palettegen-1 index 7b7ce98b76..35730a659f 100644 --- a/tests/ref/fate/filter-palettegen-1 +++ b/tests/ref/fate/filter-palettegen-1 @@ -3,4 +3,4 @@ #codec_id 0: rawvideo #dimensions 0: 16x16 #sar 0: 1/1 -0, 0, 0, 1, 1024, 0xf1fb64c1 +0, 0, 0, 1, 1024, 0xd8fd2c22 diff --git a/tests/ref/fate/filter-palettegen-2 b/tests/ref/fate/filter-palettegen-2 index b856a79273..548902fed0 100644 --- a/tests/ref/fate/filter-palettegen-2 +++ b/tests/ref/fate/filter-palettegen-2 @@ -3,4 +3,4 @@ #codec_id 0: rawvideo #dimensions 0: 16x16 #sar 0: 1/1 -0, 0, 0, 1, 1024, 0xe84a671a +0, 0, 0, 1, 1024, 0xd1f29072 -- 2.38.1 _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".