Reland: [qcms] Fix build_output_lut to return correct data for parametric curves

third_party/qcms/src/tests/qcms_test_util.c

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the Chromium LICENSE file.
+
+#include "qcms_test_util.h"
+
+#include <math.h>
+#include <stdlib.h>
+
+#define MAX_FLOAT_ERROR    0.000001f
+
+void generate_source_uint8_t(unsigned char *src, const size_t length, const size_t pixel_size)

[Noel Gordon, 2016/04/19 01:06:00]

Perhaps prefix this helper with a comment ...

// Store random pixel data in the source.

[radu.velea, 2016/04/19 08:42:07]

Done.

+{
+    size_t bytes = length * pixel_size;
+    size_t i;
+
+    for (i = 0; i < bytes; ++i) {
+        *src++ = rand() & 255;
+    }
+}
+
+// Parametric Fn using floating point <from lcms>: DefaultEvalParametricFn

[Noel Gordon, 2016/04/19 01:06:01]

DefaultEvalParametricFn() is in which LCMS file?  Perhaps mention that here to
provide a cross reference.

[radu.velea, 2016/04/19 08:42:07]

Done.

+float evaluate_parametric_curve(int type, const float params[], float r)
+{
+    float e, val, disc;
+
+    switch (type) {
+
+    // X = Y ^ Gamma
+    case 1:
+        if (r < 0) {
+
+            if (fabs(params[0] - 1.0) < MAX_FLOAT_ERROR)
+                val = r;
+            else
+                val = 0;
+        }
+        else
+            val = pow(r, params[0]);
+        break;
+
+        // Type 1 Reversed: X = Y ^1/gamma
+    case -1:
+        if (r < 0) {
+
+            if (fabs(params[0] - 1.0) < MAX_FLOAT_ERROR)
+                val = r;
+            else
+                val = 0;
+        }
+        else
+            val = pow(r, 1/params[0]);
+        break;
+
+        // CIE 122-1966
+        // Y = (aX + b)^Gamma  | X >= -b/a
+        // Y = 0               | else
+    case 2:
+        disc = -params[2] / params[1];
+
+        if (r >= disc ) {
+
+            e = params[1]*r + params[2];
+
+            if (e > 0)
+                val = pow(e, params[0]);
+            else
+                val = 0;
+        }
+        else
+            val = 0;
+        break;
+
+        // Type 2 Reversed
+        // X = (Y ^1/g  - b) / a
+    case -2:
+        if (r < 0)
+            val = 0;
+        else
+            val = (pow(r, 1.0/params[0]) - params[2]) / params[1];
+
+        if (val < 0)
+            val = 0;
+        break;
+
+
+        // IEC 61966-3
+        // Y = (aX + b)^Gamma | X <= -b/a
+        // Y = c              | else
+    case 3:
+        disc = -params[2] / params[1];
+        if (disc < 0)
+            disc = 0;
+
+        if (r >= disc) {
+
+            e = params[1]*r + params[2];
+
+            if (e > 0)
+                val = pow(e, params[0]) + params[3];
+            else
+                val = 0;
+        }
+        else
+            val = params[3];
+        break;
+
+
+        // Type 3 reversed
+        // X=((Y-c)^1/g - b)/a      | (Y>=c)
+        // X=-b/a                   | (Y<c)
+    case -3:
+        if (r >= params[3])  {
+
+            e = r - params[3];
+
+            if (e > 0)
+                val = (pow(e, 1/params[0]) - params[2]) / params[1];
+            else
+                val = 0;
+        }
+        else {
+            val = -params[2] / params[1];
+        }
+        break;
+
+
+        // IEC 61966-2.1 (sRGB)
+            // Y = (aX + b)^Gamma | X >= d
+            // Y = cX             | X < d
+    case 4:
+        if (r >= params[4]) {
+
+            e = params[1]*r + params[2];
+
+            if (e > 0)
+                val = pow(e, params[0]);
+            else
+                val = 0;
+        }
+        else
+            val = r * params[3];
+        break;
+
+        // Type 4 reversed
+        // X=((Y^1/g-b)/a)    | Y >= (ad+b)^g
+        // X=Y/c              | Y< (ad+b)^g
+    case -4:
+        e = params[1] * params[4] + params[2];
+        if (e < 0)
+            disc = 0;
+        else
+            disc = pow(e, params[0]);
+
+        if (r >= disc) {
+
+            val = (pow(r, 1.0/params[0]) - params[2]) / params[1];
+        }
+        else {
+            val = r / params[3];
+        }
+        break;
+
+
+        // Y = (aX + b)^Gamma + e | X >= d
+                // Y = cX + f             | X < d
+    case 5:
+        if (r >= params[4]) {
+
+            e = params[1]*r + params[2];
+
+            if (e > 0)
+                val = pow(e, params[0]) + params[5];
+            else
+                val = params[5];
+        }
+        else
+            val = r*params[3] + params[6];
+        break;
+
+
+        // Reversed type 5
+        // X=((Y-e)1/g-b)/a   | Y >=(ad+b)^g+e), cd+f
+        // X=(Y-f)/c          | else
+    case -5:
+
+        disc = params[3] * params[4] + params[6];
+        if (r >= disc) {
+
+            e = r - params[5];
+            if (e < 0)
+                val = 0;
+            else
+                val = (pow(e, 1.0/params[0]) - params[2]) / params[1];
+        }
+        else {
+            val = (r - params[6]) / params[3];
+        }
+        break;
+
+
+        // Types 6,7,8 comes from segmented curves as described in ICCSpecRevision_02_11_06_Float.pdf
+        // Type 6 is basically identical to type 5 without d
+
+        // Y = (a * X + b) ^ Gamma + c
+    case 6:
+        e = params[1]*r + params[2];
+
+        if (e < 0)
+            val = params[3];
+        else
+            val = pow(e, params[0]) + params[3];
+        break;
+
+        // ((Y - c) ^1/Gamma - b) / a
+    case -6:
+        e = r - params[3];
+        if (e < 0)
+            val = 0;
+        else
+            val = (pow(e, 1.0/params[0]) - params[2]) / params[1];
+        break;
+
+
+        // Y = a * log (b * X^Gamma + c) + d
+    case 7:
+
+        e = params[2] * pow(r, params[0]) + params[3];
+        if (e <= 0)
+            val = params[4];
+        else
+            val = params[1]*log10(e) + params[4];
+        break;
+
+        // (Y - d) / a = log(b * X ^Gamma + c)
+        // pow(10, (Y-d) / a) = b * X ^Gamma + c
+        // pow((pow(10, (Y-d) / a) - c) / b, 1/g) = X
+    case -7:
+        val = pow((pow(10.0, (r-params[4]) / params[1]) - params[3]) / params[2], 1.0 / params[0]);
+        break;
+
+
+        //Y = a * b^(c*X+d) + e
+    case 8:
+        val = (params[0] * pow(params[1], params[2] * r + params[3]) + params[4]);
+        break;
+
+
+        // Y = (log((y-e) / a) / log(b) - d ) / c
+        // a=0, b=1, c=2, d=3, e=4,
+    case -8:
+
+        disc = r - params[4];
+        if (disc < 0) val = 0;
+        else
+            val = (log(disc / params[0]) / log(params[1]) - params[3]) / params[2];
+        break;
+
+        // S-Shaped: (1 - (1-x)^1/g)^1/g
+    case 108:
+        val = pow(1.0 - pow(1 - r, 1/params[0]), 1/params[0]);
+        break;
+
+        // y = (1 - (1-x)^1/g)^1/g
+        // y^g = (1 - (1-x)^1/g)
+        // 1 - y^g = (1-x)^1/g
+        // (1 - y^g)^g = 1 - x
+        // 1 - (1 - y^g)^g
+    case -108:
+        val = 1 - pow(1 - pow(r, params[0]), params[0]);
+        break;
+
+    default:
+        // Unsupported parametric curve. Should never reach here
+        return 0;
+    }
+
+    return val;
+}