Revert "use linear segment instead of recalculating it"
This reverts commit 86807d30cc2951021e81dc4507a5c14b37aebd31.
Reason for revert: <INSERT REASONING HERE>
Original change's description:
> use linear segment instead of recalculating it
>
> Change-Id: I55f8e5d23f7f77681f45cfe2255ef8dda416497f
> Reviewed-on: https://skia-review.googlesource.com/123583
> Reviewed-by: Brian Osman <brianosman@google.com>
> Commit-Queue: Brian Osman <brianosman@google.com>
> Commit-Queue: Mike Klein <mtklein@google.com>
> Auto-Submit: Mike Klein <mtklein@chromium.org>
TBR=mtklein@chromium.org,mtklein@google.com,brianosman@google.com
Change-Id: Ia4703dcaea1b58a9791e7907078a8c6af588539a
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://skia-review.googlesource.com/123680
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
diff --git a/profiles/misc/MartiMaria_browsertest_HARD.icc.txt b/profiles/misc/MartiMaria_browsertest_HARD.icc.txt
index 38fdd04..46b4cf2 100644
--- a/profiles/misc/MartiMaria_browsertest_HARD.icc.txt
+++ b/profiles/misc/MartiMaria_browsertest_HARD.icc.txt
@@ -49,4 +49,4 @@
7b8069 7b8069 7b8069 7b8069 7b8069 7b8069 7b8069
7b8069 7b8069 7b8069 7b8069 7b8069 060605 7b8069
7b8069 7b8069 7b8069 7b8069 686c59 7b8069 7b8069
-polyTF[1] = 0 0 0.003876 inf
+polyTF[1] = 0 0 0.003876 1
diff --git a/profiles/misc/sRGB_lcms.icc.txt b/profiles/misc/sRGB_lcms.icc.txt
index 591b2f0..7030fb2 100644
--- a/profiles/misc/sRGB_lcms.icc.txt
+++ b/profiles/misc/sRGB_lcms.icc.txt
@@ -38,6 +38,6 @@
2a4215 322481 110a31 582e06 599714 03020c 4f59a4
63a91b 43292c 394539 5c3b22 548d3f 4d3018 506084
This profile ≈ sRGB.
-polyTF[0] = 0.2938 0.7042 0.07739 0.04045
-polyTF[1] = 0.2938 0.7042 0.07739 0.04045
-polyTF[2] = 0.2938 0.7042 0.07739 0.04045
+polyTF[0] = 0.2941 0.7039 0.07759 0.04314
+polyTF[1] = 0.2941 0.7039 0.07759 0.04314
+polyTF[2] = 0.2941 0.7039 0.07759 0.04314
diff --git a/profiles/mobile/Display_P3_parametric.icc.txt b/profiles/mobile/Display_P3_parametric.icc.txt
index 8916828..865645a 100644
--- a/profiles/mobile/Display_P3_parametric.icc.txt
+++ b/profiles/mobile/Display_P3_parametric.icc.txt
@@ -37,6 +37,6 @@
6c616e 5f3a66 2e5e07 5e2b62 371928 293053 5a6591
234012 34258c 120a35 673203 499209 03020d 4b58ad
4fa40f 4d2b2d 364439 683e21 448939 573317 4b5e8a
-polyTF[0] = 0.2938 0.7042 0.07739 0.04045
-polyTF[1] = 0.2938 0.7042 0.07739 0.04045
-polyTF[2] = 0.2938 0.7042 0.07739 0.04045
+polyTF[0] = 0.2941 0.7039 0.07759 0.04314
+polyTF[1] = 0.2941 0.7039 0.07759 0.04314
+polyTF[2] = 0.2941 0.7039 0.07759 0.04314
diff --git a/profiles/mobile/iPhone7p.icc.txt b/profiles/mobile/iPhone7p.icc.txt
index bb59c5e..80366bc 100644
--- a/profiles/mobile/iPhone7p.icc.txt
+++ b/profiles/mobile/iPhone7p.icc.txt
@@ -36,6 +36,6 @@
6c616e 5f3a65 2d5e07 5e2b62 371928 293053 5a6591
234012 34258c 120a35 673203 499209 03020d 4b58ad
4fa40f 4d2b2d 364439 683e21 448939 573317 4b5e8a
-polyTF[0] = 0.2941 0.704 0.077 0.039
-polyTF[1] = 0.2941 0.704 0.077 0.039
-polyTF[2] = 0.2941 0.704 0.077 0.039
+polyTF[0] = 0.2945 0.7035 0.07733 0.04314
+polyTF[1] = 0.2945 0.7035 0.07733 0.04314
+polyTF[2] = 0.2945 0.7035 0.07733 0.04314
diff --git a/profiles/mobile/sRGB_parametric.icc.txt b/profiles/mobile/sRGB_parametric.icc.txt
index 05bed41..04c70cc 100644
--- a/profiles/mobile/sRGB_parametric.icc.txt
+++ b/profiles/mobile/sRGB_parametric.icc.txt
@@ -38,6 +38,6 @@
2a4215 322481 110a31 582e06 599714 03020c 4f59a4
63a91b 43292c 394539 5c3b22 548d3f 4d3018 506084
This profile ≈ sRGB.
-polyTF[0] = 0.2938 0.7042 0.07739 0.04045
-polyTF[1] = 0.2938 0.7042 0.07739 0.04045
-polyTF[2] = 0.2938 0.7042 0.07739 0.04045
+polyTF[0] = 0.2941 0.7039 0.07759 0.04314
+polyTF[1] = 0.2941 0.7039 0.07759 0.04314
+polyTF[2] = 0.2941 0.7039 0.07759 0.04314
diff --git a/src/PolyTF.c b/src/PolyTF.c
index 4b31b18..451a427 100644
--- a/src/PolyTF.c
+++ b/src/PolyTF.c
@@ -66,7 +66,7 @@
}
const int N = curve->table_entries == 0 ? 256
- : (int)curve->table_entries;
+ :(int)curve->table_entries;
// We'll test the quality of our fit by roundtripping through a skcms_TransferFunction,
// either the inverse of the curve itself if it is parametric, or of its approximation if not.
@@ -77,74 +77,64 @@
} else if (!skcms_ApproximateCurve(curve, &baseline, &err)) {
return false;
}
-
- // We'll borrow the linear section from baseline, which is either
- // exactly correct, or already the approximation we'd use anyway.
- tf->C = baseline.c;
- tf->D = baseline.d;
- if (baseline.f != 0) {
- return false; // Can't fit this (rare) kind of curve here.
- }
-
- // Detect linear baseline: (ax + b)^g + e --> ax ~~> Cx
- if (baseline.g == 1 && baseline.d == 0 && baseline.b + baseline.e == 0) {
- tf->A = 0;
- tf->B = 0;
- tf->C = baseline.a;
- tf->D = INFINITY_; // Always use Cx, never Ax^3+Bx^2+(1-A-B)
- return true;
- }
- // This case is less likely, but also guards against divide by zero below.
- if (tf->D == 1) {
- tf->A = 0;
- tf->B = 0;
- return true;
- }
-
- // Number of points already fit in the linear section.
- // If the curve isn't parametric and we approximated instead, this should be exact.
- const int L = (int)(tf->D * (N-1)) + 1;
-
- // TODO: handle special case of L == N-1 to avoid /0 in Gauss-Newton.
-
skcms_TransferFunction inv;
if (!skcms_TransferFunction_invert(&baseline, &inv)) {
return false;
}
- // Start with guess A = 0, i.e. f(x) ≈ x^2.
- float P[4] = {0, 0,0,0};
- for (int i = 0; i < 3; i++) {
- if (!skcms_gauss_newton_step(skcms_eval_curve, curve,
- eval_poly_tf, tf,
- grad_poly_tf, tf,
- P,
- tf->D, 1, N-L)) {
+ const float kTolerances[] = { 1.5f / 65535.0f, 1.0f / 512.0f };
+ for (int t = 0; t < ARRAY_COUNT(kTolerances); t++) {
+ float f;
+ const int L = skcms_fit_linear(curve, N, kTolerances[t], &tf->C, &tf->D, &f);
+ if (f != 0) {
return false;
}
+
+ if (tf->D == 1) {
+ tf->A = 0;
+ tf->B = 0;
+ return true;
+ }
+
+ // Start with guess A = 0, i.e. f(x) = x^2, gamma = 2.
+ float P[4] = {0, 0,0,0};
+
+ for (int i = 0; i < 3; i++) {
+ if (!skcms_gauss_newton_step(skcms_eval_curve, curve,
+ eval_poly_tf, tf,
+ grad_poly_tf, tf,
+ P,
+ tf->D, 1, N-L)) {
+ goto NEXT;
+ }
+ }
+
+ float A = tf->A = P[0],
+ C = tf->C,
+ D = tf->D;
+ tf->B = (C*D - A*(D*D*D - 1) - 1) / (D*D - 1);
+
+ for (int i = 0; i < N; i++) {
+ float x = i * (1.0f/(N-1));
+
+ float rt = skcms_TransferFunction_eval(&inv, eval_poly_tf(x, tf, P));
+ if (!isfinitef_(rt)) {
+ goto NEXT;
+ }
+
+ const int tol = (i == 0 || i == N-1) ? 0
+ : N/256;
+ int ix = (int)((N-1) * rt + 0.5f);
+ if (abs(i - ix) > tol) {
+ goto NEXT;
+ }
+ }
+ return true;
+
+ NEXT: ;
}
- float A = tf->A = P[0],
- C = tf->C,
- D = tf->D;
- tf->B = (C*D - A*(D*D*D - 1) - 1) / (D*D - 1);
-
- for (int i = 0; i < N; i++) {
- float x = i * (1.0f/(N-1));
-
- float rt = skcms_TransferFunction_eval(&inv, eval_poly_tf(x, tf, P));
- if (!isfinitef_(rt)) {
- return false;
- }
-
- const int tol = (i == 0 || i == N-1) ? 0
- : N/256;
- int ix = (int)((N-1) * rt + 0.5f);
- if (abs(i - ix) > tol) {
- return false;
- }
- }
- return true;
+ return false;
}
void skcms_OptimizeForSpeed(skcms_ICCProfile* profile) {
