swscale: add ICC intent enum and option

This setting can be used to infuence the type of tone and gamut mapping used internally when color space conversions are required. As discussed at VDD'24, the default was set to relative colorimetric clipping, which is approximately associative, surjective and idempotent. As such, it roundtrips well, although it is strictly speaking not associative on out-of-gamut colors.

Niklas Haas committed 1 year ago

Commit 45f0a7a1 parent 7b7c3238 files · +62 −8Browse files

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8 files

doc/APIchanges +3 −0
doc/filters.texi +31 −0
libswscale/graph.c +6 −5
libswscale/options.c +6 −0
libswscale/swscale.h +13 −0
libswscale/swscale_internal.h +1 −1
libswscale/version.h +1 −1
libswscale/x86/output.asm +1 −1

doc/APIchanges+3−0

@@ -2,6 +2,9 @@ The last version increases of all libraries were on 2024-03-07 · 1 unmodified line
2	2
3	3	API changes, most recent first:
4	4
	5	+2024-12-xx - xxxxxxxxxx - lsws 8.13.100 - swscale.h
	6	+ Add enum SwsIntent and SwsContext.intent.
	7	+
5	8	2024-12-15 - xxxxxxxxxx - lavc 61.27.100 packet.h
6	9	Add av_container_fifo_alloc_avpacket().
7	10

doc/filters.texi+31−0

@@ -21071,7 +21071,38 @@ Set libswscale input parameters for scaling algorithms that need them. See · 21070 unmodified lines
21071	21071	complete documentation. If not explicitly specified the filter applies
21072	21072	empty parameters.
21073	21073
	21074	+@item intent
	21075	+Set the ICC rendering intent to use when transforming between different color
	21076	+spaces. It accepts the following values:
21074	21077
	21078	+@table @samp
	21079	+@item perceptual
	21080	+Use a perceptually guided tone and gamut mapping curve. The exact details of
	21081	+the mapping used may change at any time and should not be relied on as stable.
	21082	+This intent is recommended for final viewing of image/video content in typical
	21083	+viewing settings.
	21084	+
	21085	+@item relative_colorimetric
	21086	+Statically clip out-of-gamut colors using a colorimetric clipping curve which
	21087	+attempts to find the colorimetrically least dissimilar in-gamut color. This
	21088	+intent performs white point adaptation and black point adaptation. This is
	21089	+the default. This intent is recommended wherever faithful color reproduction
	21090	+is of the utmost importance, even at the cost of clipping.
	21091	+
	21092	+@item absolute_colorimetric
	21093	+Hard clip out-of-gamut colors with no attempt at white or black point
	21094	+reproduction. This intent will reproduce in-gamut colors 1:1 on the output
	21095	+display as they would appear on the reference display, assuming the output
	21096	+display is appropriately calibrated.
	21097	+
	21098	+@item saturation
	21099	+Performs saturation mapping - that is, stretches the input color volume
	21100	+directly onto the output color volume, in non-linear fashion that preserves the
	21101	+original signal appearance as much as possible. This intent is recommended for
	21102	+signal content evaluation, as it will not lead to any clipping. It is roughly
	21103	+analogous to not performing any color mapping, although it still takes into
	21104	+account the mastering display primaries and any differences in encoding TRC.
	21105	+@end table
21075	21106
21076	21107	@item size, s
21077	21108	Set the video size. For the syntax of this option, check the

libswscale/graph.c+6−5

@@ -570,15 +570,16 @@ void sws_graph_free(SwsGraph **pgraph) · 569 unmodified lines
570	570	/* Tests only options relevant to SwsGraph */
571	571	static int opts_equal(const SwsContext c1, const SwsContext c2)
572	572	{
573		− return c1->flags == c2->flags &&
574		− c1->threads == c2->threads &&
575		− c1->dither == c2->dither &&
576		− c1->alpha_blend == c2->alpha_blend &&
577		− c1->gamma_flag == c2->gamma_flag &&
	573	+ return c1->flags == c2->flags &&
	574	+ c1->threads == c2->threads &&
	575	+ c1->dither == c2->dither &&
	576	+ c1->alpha_blend == c2->alpha_blend &&
	577	+ c1->gamma_flag == c2->gamma_flag &&
578	578	c1->src_h_chr_pos == c2->src_h_chr_pos &&
579	579	c1->src_v_chr_pos == c2->src_v_chr_pos &&
580	580	c1->dst_h_chr_pos == c2->dst_h_chr_pos &&
581	581	c1->dst_v_chr_pos == c2->dst_v_chr_pos &&
	582	+ c1->intent == c2->intent &&
582	583	!memcmp(c1->scaler_params, c2->scaler_params, sizeof(c1->scaler_params));
583	584
584	585	}

libswscale/options.c+6−0

@@ -84,6 +84,12 @@ static const AVOption swscale_options[] = { · 83 unmodified lines
84	84	{ "threads", "number of threads", OFFSET(threads), AV_OPT_TYPE_INT, {.i64 = 1 }, .flags = VE, .unit = "threads", .max = INT_MAX },
85	85	{ "auto", "automatic selection", 0, AV_OPT_TYPE_CONST, {.i64 = 0 }, .flags = VE, .unit = "threads" },
86	86
	87	+ { "intent", "color mapping intent", OFFSET(intent), AV_OPT_TYPE_INT, { .i64 = SWS_INTENT_RELATIVE_COLORIMETRIC }, .flags = VE, .unit = "intent", .max = SWS_INTENT_NB - 1 },
	88	+ { "perceptual", "perceptual tone mapping", 0, AV_OPT_TYPE_CONST, { .i64 = SWS_INTENT_PERCEPTUAL }, .flags = VE, .unit = "intent" },
	89	+ { "relative_colorimetric", "relative colorimetric clipping", 0, AV_OPT_TYPE_CONST, { .i64 = SWS_INTENT_RELATIVE_COLORIMETRIC }, .flags = VE, .unit = "intent" },
	90	+ { "saturation", "saturation mapping", 0, AV_OPT_TYPE_CONST, { .i64 = SWS_INTENT_SATURATION }, .flags = VE, .unit = "intent" },
	91	+ { "absolute_colorimetric", "absolute colorimetric clipping", 0, AV_OPT_TYPE_CONST, { .i64 = SWS_INTENT_ABSOLUTE_COLORIMETRIC }, .flags = VE, .unit = "intent" },
	92	+
87	93	{ NULL }
88	94	};
89	95

libswscale/swscale.h+13−0

@@ -162,6 +162,14 @@ typedef enum SwsFlags { · 161 unmodified lines
162	162	SWS_ERROR_DIFFUSION = 1 << 23, ///< Set `SwsContext.dither` instead
163	163	} SwsFlags;
164	164
	165	+typedef enum SwsIntent {
	166	+ SWS_INTENT_PERCEPTUAL = 0, ///< Perceptual tone mapping
	167	+ SWS_INTENT_RELATIVE_COLORIMETRIC = 1, ///< Relative colorimetric clipping
	168	+ SWS_INTENT_SATURATION = 2, ///< Saturation mapping
	169	+ SWS_INTENT_ABSOLUTE_COLORIMETRIC = 3, ///< Absolute colorimetric clipping
	170	+ SWS_INTENT_NB, ///< not part of the ABI
	171	+} SwsIntent;
	172	+
165	173	/***********************************
166	174	* Context creation and management *
167	175	***********************************/
@@ -226,6 +234,11 @@ typedef struct SwsContext { · 58 unmodified lines
226	234	int dst_v_chr_pos; ///< Destination vertical chroma position
227	235	int dst_h_chr_pos; ///< Destination horizontal chroma position
228	236
	237	+ /**
	238	+ * Desired ICC intent for color space conversions.
	239	+ */
	240	+ int intent;
	241	+
229	242	/* Remember to add new fields to graph.c:opts_equal() */
230	243	} SwsContext;
231	244

libswscale/swscale_internal.h+1−1

@@ -699,7 +699,7 @@ static_assert(offsetof(SwsInternal, redDither) + DITHER32_INT == offsetof(SwsInt · 698 unmodified lines
699	699	#if ARCH_X86_64
700	700	/* x86 yuv2gbrp uses the SwsInternal for yuv coefficients
701	701	if struct offsets change the asm needs to be updated too */
702		−static_assert(offsetof(SwsInternal, yuv2rgb_y_offset) == 40332,
	702	+static_assert(offsetof(SwsInternal, yuv2rgb_y_offset) == 40348,
703	703	"yuv2rgb_y_offset must be updated in x86 asm");
704	704	#endif
705	705

libswscale/version.h+1−1

@@ -28,7 +28,7 @@ · 27 unmodified lines
28	28
29	29	#include "version_major.h"
30	30
31		−#define LIBSWSCALE_VERSION_MINOR 12
	31	+#define LIBSWSCALE_VERSION_MINOR 13
32	32	#define LIBSWSCALE_VERSION_MICRO 100
33	33
34	34	#define LIBSWSCALE_VERSION_INT AV_VERSION_INT(LIBSWSCALE_VERSION_MAJOR, \

libswscale/x86/output.asm+1−1

@@ -582,7 +582,7 @@ yuv2nv12cX_fn yuv2nv21 · 581 unmodified lines
582	582
583	583	%if ARCH_X86_64
584	584	struc SwsInternal
585		− .padding: resb 40332 ; offsetof(SwsInternal, yuv2rgb_y_offset)
	585	+ .padding: resb 40348 ; offsetof(SwsInternal, yuv2rgb_y_offset)
586	586	.yuv2rgb_y_offset: resd 1
587	587	.yuv2rgb_y_coeff: resd 1
588	588	.yuv2rgb_v2r_coeff: resd 1

swscale: add ICC intent enum and option

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