[FFmpeg-devel] [PATCH 1/2] avfilter/vf_nlmeans: better weighting of centered pixel

[Paul B Mahol]

Signed-off-by: Paul B Mahol <onemda at gmail.com>
---
 libavfilter/vf_nlmeans.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/libavfilter/vf_nlmeans.c b/libavfilter/vf_nlmeans.c
index 82e779ce85..6c9c9d312d 100644
--- a/libavfilter/vf_nlmeans.c
+++ b/libavfilter/vf_nlmeans.c
@@ -39,6 +39,7 @@
 #include "video.h"
 
 struct weighted_avg {
+    float max_weight;
     float total_weight;
     float sum;
 };
@@ -403,6 +404,7 @@ static int nlmeans_slice(AVFilterContext *ctx, void *arg, int jobnr, int nb_jobs
             if (patch_diff_sq < s->max_meaningful_diff) {
                 const unsigned weight_lut_idx = patch_diff_sq * s->pdiff_lut_scale;
                 const float weight = s->weight_lut[weight_lut_idx]; // exp(-patch_diff_sq * s->pdiff_scale)
+                wa[x].max_weight = FFMAX(weight, wa[x].max_weight);
                 wa[x].total_weight += weight;
                 wa[x].sum += weight * src[x];
             }
@@ -422,8 +424,10 @@ static void weight_averages(uint8_t *dst, ptrdiff_t dst_linesize,
     for (y = 0; y < h; y++) {
         for (x = 0; x < w; x++) {
             // Also weight the centered pixel
-            wa[x].total_weight += 1.f;
-            wa[x].sum += 1.f * src[x];
+            if (!isnormal(wa[x].max_weight))
+                wa[x].max_weight = 1.f;
+            wa[x].total_weight += wa[x].max_weight;
+            wa[x].sum += src[x] * wa[x].max_weight;
             dst[x] = av_clip_uint8(wa[x].sum / wa[x].total_weight);
         }
         dst += dst_linesize;
-- 
2.11.0