From: mirs <fangpengch...@bilibili.com>
Signed-off-by: mirs <fangpengch...@bilibili.com>
add tonemapping hermite,this looks close real hdr display
format patch email
---
libavfilter/vf_tonemap.c | 65 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 65 insertions(+)
diff --git a/libavfilter/vf_tonemap.c b/libavfilter/vf_tonemap.c
index d1087e6bd9..3fb2bdfa2c 100644
--- a/libavfilter/vf_tonemap.c
+++ b/libavfilter/vf_tonemap.c
@@ -48,6 +48,7 @@ enum TonemapAlgorithm {
TONEMAP_REINHARD,
TONEMAP_HABLE,
TONEMAP_MOBIUS,
+ TONEMAP_HERMITE,
TONEMAP_MAX,
};
@@ -106,6 +107,66 @@ static float mobius(float in, float j, double peak)
return (b * b + 2.0f * b * j + j * j) / (b - a) * (in + a) / (in + b);
}
+static float hermite(float in) {
+ /*
+ * in theory, max mastering lumi 、max content lumi frome packet side data,
+ * display max lumi from Display system value,current value is
R-REP-BT.2390 max value
+ */
+ float max_mastering_lumi = 1000.0f;
+ float max_content_lumi = 1000.0f;
+ float display_max_lumi = 400.0f; // Terminal domain 400NITS is the maximum
lumen of a normal screen
+
+ float max_in_lumi = FFMAX(max_mastering_lumi,max_content_lumi);
+ float max_out_lumi = display_max_lumi;
+ float nits = in * (display_max_lumi / max_mastering_lumi);
+
+ // clamp
+ if (nits < 0) {
+ nits = 0.0;
+ } else if (nits > max_in_lumi) {
+ nits = max_in_lumi;
+ }
+
+ if (max_in_lumi <= max_out_lumi) {
+ nits *= max_out_lumi / max_in_lumi;
+ } else {
+ // three control points
+ const float x0 = 10.0f;
+ const float y0 = 17.0;
+ float x1 = max_out_lumi * 0.75;
+ float y1 = x1;
+ float x2 = x1 + (max_in_lumi - x1) / 2.0;
+ float y2 = y1 + (max_out_lumi - y1) * 0.75;
+ // horizontal distances between the last three control points
+ float h12 = x2 - x1;
+ float h23 = max_in_lumi - x2;
+ // tangents at the last three control points
+ float m1 = (y2 - y1) / h12;
+ float m3 = (max_out_lumi - y2) / h23;
+ float m2 = (m1 + m3) / 2.0;
+
+ if (nits < x0) {
+ // scale [0.0, x0] to [0.0, y0] linearly
+ float slope = y0 / x0;
+ nits *= slope;
+ } else if (nits < x1) {
+ // scale [x0, x1] to [y0, y1] linearly
+ float slope = (y1 - y0) / (x1 - x0);
+ nits = y0 + (nits - x0) * slope;
+ } else if (nits < x2) {
+ // scale [x1, x2] to [y1, y2] using Hermite interp
+ float t = (nits - x1) / h12;
+ nits = (y1 * (1.0 + 2.0 * t) + h12 * m1 * t) * (1.0 - t) * (1.0 -
t) +(y2 * (3.0 - 2.0 * t) + h12 * m2 * (t - 1.0)) * t * t;
+ } else {
+ // scale [x2, maxInLumi] to [y2, maxOutLumi] using Hermite interp
+ float t = (nits - x2) / h23;
+ nits = (y2 * (1.0 + 2.0 * t) + h23 * m2 * t) * (1.0 - t) * (1.0 -
t) +(max_out_lumi * (3.0 - 2.0 * t) + h23 * m3 * (t - 1.0)) * t * t;
+ }
+ }
+
+ return nits;
+}
+
#define MIX(x,y,a) (x) * (1 - (a)) + (y) * (a)
static void tonemap(TonemapContext *s, AVFrame *out, const AVFrame *in,
const AVPixFmtDescriptor *desc, int x, int y, double peak)
@@ -163,6 +224,9 @@ static void tonemap(TonemapContext *s, AVFrame *out, const
AVFrame *in,
case TONEMAP_MOBIUS:
sig = mobius(sig, s->param, peak);
break;
+ case TONEMAP_HERMITE:
+ sig = hermite(sig);
+ break;
}
/* apply the computed scale factor to the color,
@@ -291,6 +355,7 @@ static const AVOption tonemap_options[] = {
{ "reinhard", 0, 0, AV_OPT_TYPE_CONST, {.i64 = TONEMAP_REINHARD},
0, 0, FLAGS, "tonemap" },
{ "hable", 0, 0, AV_OPT_TYPE_CONST, {.i64 = TONEMAP_HABLE},
0, 0, FLAGS, "tonemap" },
{ "mobius", 0, 0, AV_OPT_TYPE_CONST, {.i64 = TONEMAP_MOBIUS},
0, 0, FLAGS, "tonemap" },
+ { "hermite", 0, 0, AV_OPT_TYPE_CONST, {.i64 = TONEMAP_HERMITE},
0, 0, FLAGS, "tonemap" },
{ "param", "tonemap parameter", OFFSET(param), AV_OPT_TYPE_DOUBLE,
{.dbl = NAN}, DBL_MIN, DBL_MAX, FLAGS },
{ "desat", "desaturation strength", OFFSET(desat),
AV_OPT_TYPE_DOUBLE, {.dbl = 2}, 0, DBL_MAX, FLAGS },
{ "peak", "signal peak override", OFFSET(peak),
AV_OPT_TYPE_DOUBLE, {.dbl = 0}, 0, DBL_MAX, FLAGS },
--
2.32.1 (Apple Git-133)
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