vo_gpu: replace --icc-contrast by --icc-force-contrast

Not only does this have semantics that make far more sense, it also has
a default that makes far more sense. (Equivalent to the old
`icc-contrast=inf`)

This removes the weird 1000:1 contrast default assumption which
especially broke perceptual profiles and also screws things up for
OLED/CRT/etc.

Should probably close some issues but I honestly can't be bothered to
figure out which of the thousands colorimetry-related issues are
affected.

DOCS/interface-changes.rst

@@ -37,6 +37,9 @@ Interface changes
     - add an additional optional `albumart` argument to the `video-add` command,
       which tells mpv to load the given video as album art.
     - undeprecate `--cache-secs` option
+    - remove `--icc-contrast` and introduce `--icc-force-contrast`. The latter
+      defaults to the equivalent of the old `--icc-contrast=inf`, and can
+      instead be used to specifically set the contrast to any value.
  --- mpv 0.33.0 ---
     - add `--d3d11-exclusive-fs` flag to enable D3D11 exclusive fullscreen mode
       when the player enters fullscreen.

DOCS/man/options.rst

@@ -6358,14 +6358,15 @@ The following video options are currently all specific to ``--vo=gpu`` and
     Size of the 3D LUT generated from the ICC profile in each dimension.
     Default is 64x64x64. Sizes may range from 2 to 512.
 
-``--icc-contrast=<0-1000000|inf>``
-    Specifies an upper limit on the target device's contrast ratio. This is
-    detected automatically from the profile if possible, but for some profiles
-    it might be missing, causing the contrast to be assumed as infinite. As a
-    result, video may appear darker than intended. This only affects BT.1886
-    content. The default of 0 means no limit if the detected contrast is less
-    than 100000, and limits to 1000 otherwise. Use ``--icc-contrast=inf`` to
-    preserve the infinite contrast (most likely when using OLED displays).
+``--icc-force-contrast=<no|0-1000000|inf>``
+    Override the target device's detected contrast ratio by a specific value.
+    This is detected automatically from the profile if possible, but for some
+    profiles it might be missing, causing the contrast to be assumed as
+    infinite. As a result, video may appear darker than intended. If this is
+    the case, setting this option might help. This only affects BT.1886
+    content. The default of ``no`` means to use the profile values. The special
+    value ``inf`` causes the BT.1886 curve to be treated as a pure power gamma
+    2.4 function.
 
 ``--blend-subtitles=<yes|video|no>``
     Blend subtitles directly onto upscaled video frames, before interpolation

video/out/gpu/lcms.c

@@ -84,11 +84,12 @@ const struct m_sub_options mp_icc_conf = {
         {"icc-profile-auto", OPT_FLAG(profile_auto)},
         {"icc-cache-dir", OPT_STRING(cache_dir), .flags = M_OPT_FILE},
         {"icc-intent", OPT_INT(intent)},
-        {"icc-contrast", OPT_CHOICE(contrast, {"inf", -1}),
+        {"icc-force-contrast", OPT_CHOICE(contrast, {"no", 0}, {"inf", -1}),
             M_RANGE(0, 1000000)},
         {"icc-3dlut-size", OPT_STRING_VALIDATE(size_str, validate_3dlut_size_opt)},
         {"3dlut-size", OPT_REPLACED("icc-3dlut-size")},
         {"icc-cache", OPT_REMOVED("see icc-cache-dir")},
+        {"icc-contrast", OPT_REMOVED("see icc-force-contrast")},
         {0}
     },
     .size = sizeof(struct mp_icc_opts),
@@ -272,48 +273,46 @@ static cmsHPROFILE get_vid_profile(struct gl_lcms *p, cmsContext cms,
         break;
 
     case MP_CSP_TRC_BT_1886: {
-        // To build an appropriate BT.1886 transformation we need access to
-        // the display's black point, so we LittleCMS' detection function.
-        // Relative colorimetric is used since we want to approximate the
-        // BT.1886 to the target device's actual black point even in e.g.
-        // perceptual mode
-        const int intent = MP_INTENT_RELATIVE_COLORIMETRIC;
-        cmsCIEXYZ bp_XYZ;
-        if (!cmsDetectBlackPoint(&bp_XYZ, disp_profile, intent, 0))
-            return false;
-
-        // Map this XYZ value back into the (linear) source space
-        cmsToneCurve *linear = cmsBuildGamma(cms, 1.0);
-        cmsHPROFILE rev_profile = cmsCreateRGBProfileTHR(cms, &wp_xyY, &prim_xyY,
-                (cmsToneCurve*[3]){linear, linear, linear});
-        cmsHPROFILE xyz_profile = cmsCreateXYZProfile();
-        cmsHTRANSFORM xyz2src = cmsCreateTransformTHR(cms,
-                xyz_profile, TYPE_XYZ_DBL, rev_profile, TYPE_RGB_DBL,
-                intent, 0);
-        cmsFreeToneCurve(linear);
-        cmsCloseProfile(rev_profile);
-        cmsCloseProfile(xyz_profile);
-        if (!xyz2src)
-            return false;
-
         double src_black[3];
-        cmsDoTransform(xyz2src, &bp_XYZ, src_black, 1);
-        cmsDeleteTransform(xyz2src);
-
-        // Contrast limiting
-        if (p->opts->contrast > 0) {
+        if (p->opts->contrast < 0) {
+            // User requested infinite contrast, return 2.4 profile
+            tonecurve[0] = cmsBuildGamma(cms, 2.4);
+            break;
+        } else if (p->opts->contrast > 0) {
+            MP_VERBOSE(p, "Using specified contrast: %d\n", p->opts->contrast);
             for (int i = 0; i < 3; i++)
-                src_black[i] = MPMAX(src_black[i], 1.0 / p->opts->contrast);
-        }
+                src_black[i] = 1.0 / p->opts->contrast;
+        } else {
+            // To build an appropriate BT.1886 transformation we need access to
+            // the display's black point, so we use LittleCMS' detection
+            // function. Relative colorimetric is used since we want to
+            // approximate the BT.1886 to the target device's actual black
+            // point even in e.g. perceptual mode
+            const int intent = MP_INTENT_RELATIVE_COLORIMETRIC;
+            cmsCIEXYZ bp_XYZ;
+            if (!cmsDetectBlackPoint(&bp_XYZ, disp_profile, intent, 0))
+                return false;
 
-        // Built-in contrast failsafe
-        double contrast = 3.0 / (src_black[0] + src_black[1] + src_black[2]);
-        MP_VERBOSE(p, "Detected ICC profile contrast: %f\n", contrast);
-        if (contrast > 100000 && !p->opts->contrast) {
-            MP_WARN(p, "ICC profile detected contrast very high (>100000),"
-                    " falling back to contrast 1000 for sanity. Set the"
-                    " icc-contrast option to silence this warning.\n");
-            src_black[0] = src_black[1] = src_black[2] = 1.0 / 1000;
+            // Map this XYZ value back into the (linear) source space
+            cmsHPROFILE rev_profile;
+            cmsToneCurve *linear = cmsBuildGamma(cms, 1.0);
+            rev_profile = cmsCreateRGBProfileTHR(cms, &wp_xyY, &prim_xyY,
+                    (cmsToneCurve*[3]){linear, linear, linear});
+            cmsHPROFILE xyz_profile = cmsCreateXYZProfile();
+            cmsHTRANSFORM xyz2src = cmsCreateTransformTHR(cms,
+                    xyz_profile, TYPE_XYZ_DBL, rev_profile, TYPE_RGB_DBL,
+                    intent, 0);
+            cmsFreeToneCurve(linear);
+            cmsCloseProfile(rev_profile);
+            cmsCloseProfile(xyz_profile);
+            if (!xyz2src)
+                return false;
+
+            cmsDoTransform(xyz2src, &bp_XYZ, src_black, 1);
+            cmsDeleteTransform(xyz2src);
+
+            double contrast = 3.0 / (src_black[0] + src_black[1] + src_black[2]);
+            MP_VERBOSE(p, "Detected ICC profile contrast: %f\n", contrast);
         }
 
         // Build the parametric BT.1886 transfer curve, one per channel