Add a new flag to the vf_colorspace filter which provides the user an
option to clamp the linear and delinear transfer characteristics LUT
values to the [0, 1] represented range. This helps constrain the
potential value range when converting between colorspaces.
Signed-off-by: Drew Dunne <asdu...@google.com>
---
doc/filters.texi | 3 +++
libavfilter/vf_colorspace.c | 14 ++++++++++++--
2 files changed, 15 insertions(+), 2 deletions(-)
diff --git a/doc/filters.texi b/doc/filters.texi
index 908c98a3cf..cb09d73f62 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -10403,6 +10403,9 @@ von Kries whitepoint adaptation
identity whitepoint adaptation (i.e. no whitepoint adaptation)
@end table
+@item clamptrc
+Clamps the linear and delinear transfer characteristics LUT values to the [0,
1] represented range.
+
@item iall
Override all input properties at once. Same accepted values as @ref{all}.
diff --git a/libavfilter/vf_colorspace.c b/libavfilter/vf_colorspace.c
index e1f4725f63..15b4858b24 100644
--- a/libavfilter/vf_colorspace.c
+++ b/libavfilter/vf_colorspace.c
@@ -123,6 +123,7 @@ typedef struct ColorSpaceContext {
int fast_mode;
enum DitherMode dither;
enum WhitepointAdaptation wp_adapt;
+ int clamp_trc;
int16_t *rgb[3];
ptrdiff_t rgb_stride;
@@ -215,7 +216,9 @@ static int fill_gamma_table(ColorSpaceContext *s)
} else {
d = out_alpha * pow(v, out_gamma) - (out_alpha - 1.0);
}
- s->delin_lut[n] = av_clip_int16(lrint(d * 28672.0));
+ long d_rounded = lrint(d * 28672.0);
+ s->delin_lut[n] = s->clamp_trc ? av_clip64(d_rounded, 0, 28672)
+ : av_clip_int16(d_rounded);
// linearize
if (v <= -in_beta * in_delta) {
@@ -225,7 +228,9 @@ static int fill_gamma_table(ColorSpaceContext *s)
} else {
l = pow((v + in_alpha - 1.0) * in_ialpha, in_igamma);
}
- s->lin_lut[n] = av_clip_int16(lrint(l * 28672.0));
+ long l_rounded = lrint(l * 28672.0);
+ s->lin_lut[n] = s->clamp_trc ? av_clip64(l_rounded, 0, 28672)
+ : av_clip_int16(l_rounded);
}
return 0;
@@ -1000,6 +1005,11 @@ static const AVOption colorspace_options[] = {
ENUM("vonkries", WP_ADAPT_VON_KRIES, "wpadapt"),
ENUM("identity", WP_ADAPT_IDENTITY, "wpadapt"),
+ { "clamptrc",
+ "Clamps the linear and delinear LUT output values to the range [0, 1].",
+ OFFSET(clamp_trc), AV_OPT_TYPE_BOOL, { .i64 = 0 },
+ 0, 1, FLAGS },
+
{ "iall", "Set all input color properties together",
OFFSET(user_iall), AV_OPT_TYPE_INT, { .i64 = CS_UNSPECIFIED },
CS_UNSPECIFIED, CS_NB - 1, FLAGS, .unit = "all" },
--
2.51.0.rc1.167.g924127e9c0-goog
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