avfilter/vf_blend: add hardmix mode

Signed-off-by: Paul B Mahol <onemda@gmail.com>

doc/filters.texi

@@ -2749,6 +2749,7 @@ Available values for component modes are:
 @item dodge
 @item exclusion
 @item hardlight
+@item hardmix
 @item lighten
 @item multiply
 @item negation

libavfilter/vf_blend.c

@@ -59,6 +59,7 @@ enum BlendMode {
     BLEND_SUBTRACT,
     BLEND_VIVIDLIGHT,
     BLEND_XOR,
+    BLEND_HARDMIX,
     BLEND_NB
 };
 
@@ -117,6 +118,7 @@ typedef struct {
     { "dodge",      "", 0, AV_OPT_TYPE_CONST, {.i64=BLEND_DODGE},      0, 0, FLAGS, "mode" },\
     { "exclusion",  "", 0, AV_OPT_TYPE_CONST, {.i64=BLEND_EXCLUSION},  0, 0, FLAGS, "mode" },\
     { "hardlight",  "", 0, AV_OPT_TYPE_CONST, {.i64=BLEND_HARDLIGHT},  0, 0, FLAGS, "mode" },\
+    { "hardmix",    "", 0, AV_OPT_TYPE_CONST, {.i64=BLEND_HARDMIX},    0, 0, FLAGS, "mode" },\
     { "lighten",    "", 0, AV_OPT_TYPE_CONST, {.i64=BLEND_LIGHTEN},    0, 0, FLAGS, "mode" },\
     { "multiply",   "", 0, AV_OPT_TYPE_CONST, {.i64=BLEND_MULTIPLY},   0, 0, FLAGS, "mode" },\
     { "negation",   "", 0, AV_OPT_TYPE_CONST, {.i64=BLEND_NEGATION},   0, 0, FLAGS, "mode" },\
@@ -201,6 +203,7 @@ DEFINE_BLEND(difference128, av_clip_uint8(128 + A - B))
 DEFINE_BLEND(screen,     SCREEN(1, A, B))
 DEFINE_BLEND(overlay,    (A < 128) ? MULTIPLY(2, A, B) : SCREEN(2, A, B))
 DEFINE_BLEND(hardlight,  (B < 128) ? MULTIPLY(2, B, A) : SCREEN(2, B, A))
+DEFINE_BLEND(hardmix,    (A < (255 - B)) ? 0: 255)
 DEFINE_BLEND(darken,     FFMIN(A, B))
 DEFINE_BLEND(lighten,    FFMAX(A, B))
 DEFINE_BLEND(divide,     av_clip_uint8(((float)A / ((float)B) * 255)))
@@ -326,6 +329,7 @@ static av_cold int init(AVFilterContext *ctx)
         case BLEND_DODGE:      param->blend = blend_dodge;      break;
         case BLEND_EXCLUSION:  param->blend = blend_exclusion;  break;
         case BLEND_HARDLIGHT:  param->blend = blend_hardlight;  break;
+        case BLEND_HARDMIX:    param->blend = blend_hardmix;    break;
         case BLEND_LIGHTEN:    param->blend = blend_lighten;    break;
         case BLEND_MULTIPLY:   param->blend = blend_multiply;   break;
         case BLEND_NEGATION:   param->blend = blend_negation;   break;