Roll skia/third_party/skcms fe14a6a..e8bc226 (1 commits)

https://skia.googlesource.com/skcms.git/+log/fe14a6a..e8bc226

2018-04-23 mtklein@chromium.org skcms_OptimizeForSpeed()


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https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

If the roll is causing failures, please contact the current sheriff, who should
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TBR=stani@google.com

Change-Id: Ib0c40a1dc5314ee6ca18da6ddac9895977c12bdc
Reviewed-on: https://skia-review.googlesource.com/123072
Reviewed-by: skcms-skia-autoroll <skcms-skia-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Commit-Queue: skcms-skia-autoroll <skcms-skia-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>

third_party/skcms/skcms.h

@@ -73,6 +73,12 @@ typedef struct skcms_A2B {
     skcms_Curve     output_curves[3];
 } skcms_A2B;
 
+// A specialized approximation for transfer functions with gamma between 1 and 3.
+//     f(x) = sign(x) * (A|x|^3 + B|x|^2 + (1-A-B)|x|)
+typedef struct skcms_TF13 {
+    float A,B;
+} skcms_TF13;
+
 typedef struct skcms_ICCProfile {
     const uint8_t* buffer;
 
@@ -97,6 +103,10 @@ typedef struct skcms_ICCProfile {
     // and has_A2B to true.
     bool                   has_A2B;
     skcms_A2B              A2B;
+
+    // If has_trc, we may be able to approximate the curves more efficiently.
+    bool   has_tf13[3];
+    skcms_TF13 tf13[3];
 } skcms_ICCProfile;
 
 // The sRGB color profile is so commonly used that we offer a canonical skcms_ICCProfile for it.
@@ -114,15 +124,13 @@ bool skcms_ApproximatelyEqualProfiles(const skcms_ICCProfile* A, const skcms_ICC
 // will be used.
 bool skcms_Parse(const void*, size_t, skcms_ICCProfile*);
 
+// skcms_Parse() creates a profile that directs skcms_Transform() to favor accuracy.
+// If you want to trade a little accuracy for a big speedup, call skcms_OptimizeForSpeed().
+void skcms_OptimizeForSpeed(skcms_ICCProfile*);
+
 bool skcms_ApproximateCurve(const skcms_Curve* curve, skcms_TransferFunction* approx,
                             float* max_error);
 
-// A specialized approximation for transfer functions with gamma between 1 and 3.
-//     f(x) = Ax^3 + Bx^2 + (1-A-B)x
-typedef struct skcms_TF13 {
-    float A,B;
-} skcms_TF13;
-
 bool skcms_ApproximateCurve13(const skcms_Curve* curve, skcms_TF13* approx, float* max_error);
 
 // What is the best single transfer function to use for the given profile? Note that there is

third_party/skcms/src/ICCProfile.c

@@ -781,6 +781,14 @@ bool skcms_Parse(const void* buf, size_t len, skcms_ICCProfile* profile) {
     return usable_as_src(profile);
 }
 
+void skcms_OptimizeForSpeed(skcms_ICCProfile* profile) {
+    // If we can approximate any of the TRC curves with a skcms_TF13, do so.
+    for (int i = 0; profile->has_trc && i < 3; i++) {
+        float err;
+        profile->has_tf13[i] = skcms_ApproximateCurve13(&profile->trc[i], &profile->tf13[i], &err);
+    }
+}
+
 const skcms_ICCProfile skcms_sRGB_profile = {
     // These fields are moot when not a skcms_Parse()'d profile.
     .buffer    = NULL,

third_party/skcms/src/Transform.c

@@ -314,6 +314,11 @@ typedef struct {
     const void* arg;
 } OpAndArg;
 
+static OpAndArg select_tf13_op(const skcms_TF13* tf, int channel) {
+    static const Op ops[] = { Op_tf13_r, Op_tf13_g, Op_tf13_b };
+    return (OpAndArg){ ops[channel], tf };
+}
+
 static OpAndArg select_curve_op(const skcms_Curve* curve, int channel) {
     static const struct { Op parametric, table_8, table_16; } ops[] = {
         { Op_tf_r, Op_table_8_r, Op_table_16_r },
@@ -513,8 +518,13 @@ bool skcms_Transform(const void*             src,
 
         } else if (srcProfile->has_trc && srcProfile->has_toXYZD50) {
             for (int i = 0; i < 3; i++) {
+                // Favor Op_noop (identity curve) over anything else,
+                // and select_tf_op() over over select_curve_op() when possible.
                 OpAndArg oa = select_curve_op(&srcProfile->trc[i], i);
                 if (oa.op != Op_noop) {
+                    if (srcProfile->has_tf13[i]) {
+                        oa = select_tf13_op(&srcProfile->tf13[i], i);
+                    }
                     *ops++  = oa.op;
                     *args++ = oa.arg;
                 }

third_party/skcms/src/Transform.h

@@ -34,6 +34,9 @@
     M(tf_g)           \
     M(tf_b)           \
     M(tf_a)           \
+    M(tf13_r)         \
+    M(tf13_g)         \
+    M(tf13_b)         \
     M(table_8_r)      \
     M(table_8_g)      \
     M(table_8_b)      \

third_party/skcms/src/Transform_inl.h

@@ -239,6 +239,12 @@ SI ATTR F NS(apply_transfer_function_)(const skcms_TransferFunction* tf, F x) {
 }
 #define apply_transfer_function NS(apply_transfer_function_)
 
+SI ATTR F NS(apply_tf13_)(const skcms_TF13* tf, F x) {
+    F sign = (F)if_then_else(x < 0, -F1, F1);
+    return x*(x*(x*tf->A + sign*tf->B) + (1 - tf->A - tf->B) );
+}
+#define apply_tf13 NS(apply_tf13_)
+
 // Strided loads and stores of N values, starting from p.
 #if N == 1
     #define LOAD_3(T, p) (T)(p)[0]
@@ -840,6 +846,10 @@ static void NS(exec_ops)(const Op* ops, const void** args,
             case Op_tf_b:{ b = apply_transfer_function(*args++, b); } break;
             case Op_tf_a:{ a = apply_transfer_function(*args++, a); } break;
 
+            case Op_tf13_r:{ r = apply_tf13(*args++, r); } break;
+            case Op_tf13_g:{ g = apply_tf13(*args++, g); } break;
+            case Op_tf13_b:{ b = apply_tf13(*args++, b); } break;
+
             case Op_table_8_r: { r = NS(table_8_ )(*args++, r); } break;
             case Op_table_8_g: { g = NS(table_8_ )(*args++, g); } break;
             case Op_table_8_b: { b = NS(table_8_ )(*args++, b); } break;

third_party/skcms/version.sha1

@@ -1 +1 @@
-fe14a6aff9d05024284bbf576a93919c3cf8e9c4
+e8bc22664f84326c18feeb0444f573e8a0c75f42