Index: third_party/qcms/src/transform_util.c |
diff --git a/third_party/qcms/src/transform_util.c b/third_party/qcms/src/transform_util.c |
new file mode 100644 |
index 0000000000000000000000000000000000000000..e60744742c393fdba7c68293066a47b1e2a0269d |
--- /dev/null |
+++ b/third_party/qcms/src/transform_util.c |
@@ -0,0 +1,639 @@ |
+// qcms |
+// Copyright (C) 2009 Mozilla Foundation |
+// |
+// Permission is hereby granted, free of charge, to any person obtaining |
+// a copy of this software and associated documentation files (the "Software"), |
+// to deal in the Software without restriction, including without limitation |
+// the rights to use, copy, modify, merge, publish, distribute, sublicense, |
+// and/or sell copies of the Software, and to permit persons to whom the Software |
+// is furnished to do so, subject to the following conditions: |
+// |
+// The above copyright notice and this permission notice shall be included in |
+// all copies or substantial portions of the Software. |
+// |
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, |
+// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO |
+// THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND |
+// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE |
+// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION |
+// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION |
+// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. |
+ |
+#define _ISOC99_SOURCE /* for INFINITY */ |
+ |
+#include <math.h> |
+#include <assert.h> |
+#include <string.h> //memcpy |
+#include "qcmsint.h" |
+#include "transform_util.h" |
+#include "matrix.h" |
+ |
+#if !defined(INFINITY) |
+#define INFINITY HUGE_VAL |
+#endif |
+ |
+#define PARAMETRIC_CURVE_TYPE 0x70617261 //'para' |
+ |
+/* value must be a value between 0 and 1 */ |
+//XXX: is the above a good restriction to have? |
+// the output range of this function is 0..1 |
+float lut_interp_linear(double input_value, uint16_t *table, size_t length) |
+{ |
+ int upper, lower; |
+ float value; |
+ input_value = input_value * (length - 1); // scale to length of the array |
+ upper = ceil(input_value); |
+ lower = floor(input_value); |
+ //XXX: can we be more performant here? |
+ value = table[upper]*(1. - (upper - input_value)) + table[lower]*(upper - input_value); |
+ /* scale the value */ |
+ return value * (1.f/65535.f); |
+} |
+ |
+/* same as above but takes and returns a uint16_t value representing a range from 0..1 */ |
+uint16_t lut_interp_linear16(uint16_t input_value, uint16_t *table, size_t length) |
+{ |
+ /* Start scaling input_value to the length of the array: 65535*(length-1). |
+ * We'll divide out the 65535 next */ |
+ uintptr_t value = (input_value * (length - 1)); |
+ uint32_t upper = (value + 65534) / 65535; /* equivalent to ceil(value/65535) */ |
+ uint32_t lower = value / 65535; /* equivalent to floor(value/65535) */ |
+ /* interp is the distance from upper to value scaled to 0..65535 */ |
+ uint32_t interp = value % 65535; |
+ |
+ value = (table[upper]*(interp) + table[lower]*(65535 - interp))/65535; // 0..65535*65535 |
+ |
+ return value; |
+} |
+ |
+/* same as above but takes an input_value from 0..PRECACHE_OUTPUT_MAX |
+ * and returns a uint8_t value representing a range from 0..1 */ |
+static |
+uint8_t lut_interp_linear_precache_output(uint32_t input_value, uint16_t *table, size_t length) |
+{ |
+ /* Start scaling input_value to the length of the array: PRECACHE_OUTPUT_MAX*(length-1). |
+ * We'll divide out the PRECACHE_OUTPUT_MAX next */ |
+ uintptr_t value = (input_value * (length - 1)); |
+ |
+ /* equivalent to ceil(value/PRECACHE_OUTPUT_MAX) */ |
+ uint32_t upper = (value + PRECACHE_OUTPUT_MAX-1) / PRECACHE_OUTPUT_MAX; |
+ /* equivalent to floor(value/PRECACHE_OUTPUT_MAX) */ |
+ uint32_t lower = value / PRECACHE_OUTPUT_MAX; |
+ /* interp is the distance from upper to value scaled to 0..PRECACHE_OUTPUT_MAX */ |
+ uint32_t interp = value % PRECACHE_OUTPUT_MAX; |
+ |
+ /* the table values range from 0..65535 */ |
+ value = (table[upper]*(interp) + table[lower]*(PRECACHE_OUTPUT_MAX - interp)); // 0..(65535*PRECACHE_OUTPUT_MAX) |
+ |
+ /* round and scale */ |
+ value += (PRECACHE_OUTPUT_MAX*65535/255)/2; |
+ value /= (PRECACHE_OUTPUT_MAX*65535/255); // scale to 0..255 |
+ return value; |
+} |
+ |
+/* value must be a value between 0 and 1 */ |
+//XXX: is the above a good restriction to have? |
+float lut_interp_linear_float(float value, float *table, size_t length) |
+{ |
+ int upper, lower; |
+ value = value * (length - 1); |
+ upper = ceil(value); |
+ lower = floor(value); |
+ //XXX: can we be more performant here? |
+ value = table[upper]*(1. - (upper - value)) + table[lower]*(upper - value); |
+ /* scale the value */ |
+ return value; |
+} |
+ |
+#if 0 |
+/* if we use a different representation i.e. one that goes from 0 to 0x1000 we can be more efficient |
+ * because we can avoid the divisions and use a shifting instead */ |
+/* same as above but takes and returns a uint16_t value representing a range from 0..1 */ |
+uint16_t lut_interp_linear16(uint16_t input_value, uint16_t *table, int length) |
+{ |
+ uint32_t value = (input_value * (length - 1)); |
+ uint32_t upper = (value + 4095) / 4096; /* equivalent to ceil(value/4096) */ |
+ uint32_t lower = value / 4096; /* equivalent to floor(value/4096) */ |
+ uint32_t interp = value % 4096; |
+ |
+ value = (table[upper]*(interp) + table[lower]*(4096 - interp))/4096; // 0..4096*4096 |
+ |
+ return value; |
+} |
+#endif |
+ |
+void compute_curve_gamma_table_type1(float gamma_table[256], uint16_t gamma) |
+{ |
+ unsigned int i; |
+ float gamma_float = u8Fixed8Number_to_float(gamma); |
+ for (i = 0; i < 256; i++) { |
+ // 0..1^(0..255 + 255/256) will always be between 0 and 1 |
+ gamma_table[i] = pow(i/255., gamma_float); |
+ } |
+} |
+ |
+void compute_curve_gamma_table_type2(float gamma_table[256], uint16_t *table, size_t length) |
+{ |
+ unsigned int i; |
+ for (i = 0; i < 256; i++) { |
+ gamma_table[i] = lut_interp_linear(i/255., table, length); |
+ } |
+} |
+ |
+void compute_curve_gamma_table_type_parametric(float gamma_table[256], float parameter[7], int count) |
+{ |
+ size_t X; |
+ float interval; |
+ float a, b, c, e, f; |
+ float y = parameter[0]; |
+ if (count == 0) { |
+ a = 1; |
+ b = 0; |
+ c = 0; |
+ e = 0; |
+ f = 0; |
+ interval = -INFINITY; |
+ } else if(count == 1) { |
+ a = parameter[1]; |
+ b = parameter[2]; |
+ c = 0; |
+ e = 0; |
+ f = 0; |
+ interval = -1 * parameter[2] / parameter[1]; |
+ } else if(count == 2) { |
+ a = parameter[1]; |
+ b = parameter[2]; |
+ c = 0; |
+ e = parameter[3]; |
+ f = parameter[3]; |
+ interval = -1 * parameter[2] / parameter[1]; |
+ } else if(count == 3) { |
+ a = parameter[1]; |
+ b = parameter[2]; |
+ c = parameter[3]; |
+ e = -c; |
+ f = 0; |
+ interval = parameter[4]; |
+ } else if(count == 4) { |
+ a = parameter[1]; |
+ b = parameter[2]; |
+ c = parameter[3]; |
+ e = parameter[5] - c; |
+ f = parameter[6]; |
+ interval = parameter[4]; |
+ } else { |
+ assert(0 && "invalid parametric function type."); |
+ a = 1; |
+ b = 0; |
+ c = 0; |
+ e = 0; |
+ f = 0; |
+ interval = -INFINITY; |
+ } |
+ for (X = 0; X < 256; X++) { |
+ float x = X / 255.0; |
+ if (x >= interval) { |
+ // XXX The equations are not exactly as definied in the spec but are |
+ // algebraic equivilent. |
+ // TODO Should division by 255 be for the whole expression. |
+ gamma_table[X] = clamp_float(pow(a * x + b, y) + c + e); |
+ } else { |
+ gamma_table[X] = clamp_float(c * x + f); |
+ } |
+ } |
+} |
+ |
+void compute_curve_gamma_table_type0(float gamma_table[256]) |
+{ |
+ unsigned int i; |
+ for (i = 0; i < 256; i++) { |
+ gamma_table[i] = i/255.; |
+ } |
+} |
+ |
+float clamp_float(float a) |
+{ |
+ /* One would naturally write this function as the following: |
+ if (a > 1.) |
+ return 1.; |
+ else if (a < 0) |
+ return 0; |
+ else |
+ return a; |
+ |
+ However, that version will let NaNs pass through which is undesirable |
+ for most consumers. |
+ */ |
+ |
+ if (a > 1.) |
+ return 1.; |
+ else if (a >= 0) |
+ return a; |
+ else // a < 0 or a is NaN |
+ return 0; |
+} |
+ |
+unsigned char clamp_u8(float v) |
+{ |
+ if (v > 255.) |
+ return 255; |
+ else if (v < 0) |
+ return 0; |
+ else |
+ return floor(v+.5); |
+} |
+ |
+float u8Fixed8Number_to_float(uint16_t x) |
+{ |
+ // 0x0000 = 0. |
+ // 0x0100 = 1. |
+ // 0xffff = 255 + 255/256 |
+ return x/256.; |
+} |
+ |
+/* The SSE2 code uses min & max which let NaNs pass through. |
+ We want to try to prevent that here by ensuring that |
+ gamma table is within expected values. */ |
+void validate_gamma_table(float gamma_table[256]) |
+{ |
+ int i; |
+ for (i = 0; i < 256; i++) { |
+ // Note: we check that the gamma is not in range |
+ // instead of out of range so that we catch NaNs |
+ if (!(gamma_table[i] >= 0.f && gamma_table[i] <= 1.f)) { |
+ gamma_table[i] = 0.f; |
+ } |
+ } |
+} |
+ |
+float *build_input_gamma_table(struct curveType *TRC) |
+{ |
+ float *gamma_table; |
+ |
+ if (!TRC) return NULL; |
+ gamma_table = malloc(sizeof(float)*256); |
+ if (gamma_table) { |
+ if (TRC->type == PARAMETRIC_CURVE_TYPE) { |
+ compute_curve_gamma_table_type_parametric(gamma_table, TRC->parameter, TRC->count); |
+ } else { |
+ if (TRC->count == 0) { |
+ compute_curve_gamma_table_type0(gamma_table); |
+ } else if (TRC->count == 1) { |
+ compute_curve_gamma_table_type1(gamma_table, TRC->data[0]); |
+ } else { |
+ compute_curve_gamma_table_type2(gamma_table, TRC->data, TRC->count); |
+ } |
+ } |
+ } |
+ |
+ validate_gamma_table(gamma_table); |
+ |
+ return gamma_table; |
+} |
+ |
+struct matrix build_colorant_matrix(qcms_profile *p) |
+{ |
+ struct matrix result; |
+ result.m[0][0] = s15Fixed16Number_to_float(p->redColorant.X); |
+ result.m[0][1] = s15Fixed16Number_to_float(p->greenColorant.X); |
+ result.m[0][2] = s15Fixed16Number_to_float(p->blueColorant.X); |
+ result.m[1][0] = s15Fixed16Number_to_float(p->redColorant.Y); |
+ result.m[1][1] = s15Fixed16Number_to_float(p->greenColorant.Y); |
+ result.m[1][2] = s15Fixed16Number_to_float(p->blueColorant.Y); |
+ result.m[2][0] = s15Fixed16Number_to_float(p->redColorant.Z); |
+ result.m[2][1] = s15Fixed16Number_to_float(p->greenColorant.Z); |
+ result.m[2][2] = s15Fixed16Number_to_float(p->blueColorant.Z); |
+ result.invalid = false; |
+ return result; |
+} |
+ |
+/* The following code is copied nearly directly from lcms. |
+ * I think it could be much better. For example, Argyll seems to have better code in |
+ * icmTable_lookup_bwd and icmTable_setup_bwd. However, for now this is a quick way |
+ * to a working solution and allows for easy comparing with lcms. */ |
+uint16_fract_t lut_inverse_interp16(uint16_t Value, uint16_t LutTable[], int length, int NumZeroes, int NumPoles) |
+{ |
+ int l = 1; |
+ int r = 0x10000; |
+ int x = 0, res; // 'int' Give spacing for negative values |
+ int cell0, cell1; |
+ double val2; |
+ double y0, y1, x0, x1; |
+ double a, b, f; |
+ |
+ // July/27 2001 - Expanded to handle degenerated curves with an arbitrary |
+ // number of elements containing 0 at the beginning of the table (Zeroes) |
+ // and another arbitrary number of poles (FFFFh) at the end. |
+ |
+ // There are no zeros at the beginning and we are trying to find a zero, so |
+ // return anything. It seems zero would be the less destructive choice |
+ /* I'm not sure that this makes sense, but oh well... */ |
+ if (NumZeroes == 0 && Value == 0) |
+ return 0; |
+ |
+ // Does the curve belong to this case? |
+ if (NumZeroes > 1 || NumPoles > 1) |
+ { |
+ int a, b, sample; |
+ |
+ // Identify if value fall downto 0 or FFFF zone |
+ if (Value == 0) return 0; |
+ // if (Value == 0xFFFF) return 0xFFFF; |
+ sample = (length-1) * ((double) Value * (1./65535.)); |
+ if (LutTable[sample] == 0xffff) |
+ return 0xffff; |
+ |
+ // else restrict to valid zone |
+ |
+ a = ((NumZeroes-1) * 0xFFFF) / (length-1); |
+ b = ((length-1 - NumPoles) * 0xFFFF) / (length-1); |
+ |
+ l = a - 1; |
+ r = b + 1; |
+ |
+ // Ensure a valid binary search range |
+ |
+ if (l < 1) |
+ l = 1; |
+ if (r > 0x10000) |
+ r = 0x10000; |
+ |
+ // If the search range is inverted due to degeneracy, |
+ // deem LutTable non-invertible in this search range. |
+ // Refer to https://bugzil.la/1132467 |
+ |
+ if (r <= l) |
+ return 0; |
+ } |
+ |
+ // For input 0, return that to maintain black level. Note the binary search |
+ // does not. For example, it inverts the standard sRGB gamma curve to 7 at |
+ // the origin, causing a black level error. |
+ |
+ if (Value == 0 && NumZeroes) { |
+ return 0; |
+ } |
+ |
+ // Seems not a degenerated case... apply binary search |
+ |
+ while (r > l) { |
+ |
+ x = (l + r) / 2; |
+ |
+ res = (int) lut_interp_linear16((uint16_fract_t) (x-1), LutTable, length); |
+ |
+ if (res == Value) { |
+ |
+ // Found exact match. |
+ |
+ return (uint16_fract_t) (x - 1); |
+ } |
+ |
+ if (res > Value) r = x - 1; |
+ else l = x + 1; |
+ } |
+ |
+ // Not found, should we interpolate? |
+ |
+ // Get surrounding nodes |
+ |
+ assert(x >= 1); |
+ |
+ val2 = (length-1) * ((double) (x - 1) / 65535.0); |
+ |
+ cell0 = (int) floor(val2); |
+ cell1 = (int) ceil(val2); |
+ |
+ assert(cell0 >= 0); |
+ assert(cell1 >= 0); |
+ assert(cell0 < length); |
+ assert(cell1 < length); |
+ |
+ if (cell0 == cell1) return (uint16_fract_t) x; |
+ |
+ y0 = LutTable[cell0] ; |
+ x0 = (65535.0 * cell0) / (length-1); |
+ |
+ y1 = LutTable[cell1] ; |
+ x1 = (65535.0 * cell1) / (length-1); |
+ |
+ a = (y1 - y0) / (x1 - x0); |
+ b = y0 - a * x0; |
+ |
+ if (fabs(a) < 0.01) return (uint16_fract_t) x; |
+ |
+ f = ((Value - b) / a); |
+ |
+ if (f < 0.0) return (uint16_fract_t) 0; |
+ if (f >= 65535.0) return (uint16_fract_t) 0xFFFF; |
+ |
+ return (uint16_fract_t) floor(f + 0.5); |
+} |
+ |
+// December/16 2015 - Moved this code out of lut_inverse_interp16 |
+// in order to save computation in invert_lut loop. |
+static void count_zeroes_and_poles(uint16_t *LutTable, int length, int *NumZeroes, int *NumPoles) |
+{ |
+ int z = 0, p = 0; |
+ |
+ while (LutTable[z] == 0 && z < length - 1) |
+ z++; |
+ *NumZeroes = z; |
+ |
+ while (LutTable[length - 1 - p] == 0xFFFF && p < length - 1) |
+ p++; |
+ *NumPoles = p; |
+} |
+ |
+/* |
+ The number of entries needed to invert a lookup table should not |
+ necessarily be the same as the original number of entries. This is |
+ especially true of lookup tables that have a small number of entries. |
+ |
+ For example: |
+ Using a table like: |
+ {0, 3104, 14263, 34802, 65535} |
+ invert_lut will produce an inverse of: |
+ {3, 34459, 47529, 56801, 65535} |
+ which has an maximum error of about 9855 (pixel difference of ~38.346) |
+ |
+ For now, we punt the decision of output size to the caller. */ |
+static uint16_t *invert_lut(uint16_t *table, int length, size_t out_length) |
+{ |
+ int NumZeroes; |
+ int NumPoles; |
+ int i; |
+ /* for now we invert the lut by creating a lut of size out_length |
+ * and attempting to lookup a value for each entry using lut_inverse_interp16 */ |
+ uint16_t *output = malloc(sizeof(uint16_t)*out_length); |
+ if (!output) |
+ return NULL; |
+ |
+ // December/16 2015 - Compute the input curve zero and pole extents outside |
+ // the loop and pass them to lut_inverse_interp16. |
+ count_zeroes_and_poles(table, length, &NumZeroes, &NumPoles); |
+ |
+ for (i = 0; i < out_length; i++) { |
+ double x = ((double) i * 65535.) / (double) (out_length - 1); |
+ uint16_fract_t input = floor(x + .5); |
+ output[i] = lut_inverse_interp16(input, table, length, NumZeroes, NumPoles); |
+ } |
+ |
+ return output; |
+} |
+ |
+static void compute_precache_pow(uint8_t *output, float gamma) |
+{ |
+ uint32_t v = 0; |
+ for (v = 0; v < PRECACHE_OUTPUT_SIZE; v++) { |
+ //XXX: don't do integer/float conversion... and round? |
+ output[v] = 255. * pow(v/(double)PRECACHE_OUTPUT_MAX, gamma); |
+ } |
+} |
+ |
+void compute_precache_lut(uint8_t *output, uint16_t *table, int length) |
+{ |
+ uint32_t v = 0; |
+ for (v = 0; v < PRECACHE_OUTPUT_SIZE; v++) { |
+ output[v] = lut_interp_linear_precache_output(v, table, length); |
+ } |
+} |
+ |
+void compute_precache_linear(uint8_t *output) |
+{ |
+ uint32_t v = 0; |
+ for (v = 0; v < PRECACHE_OUTPUT_SIZE; v++) { |
+ //XXX: round? |
+ output[v] = v / (PRECACHE_OUTPUT_SIZE/256); |
+ } |
+} |
+ |
+qcms_bool compute_precache(struct curveType *trc, uint8_t *output) |
+{ |
+ |
+ if (trc->type == PARAMETRIC_CURVE_TYPE) { |
+ float gamma_table[256]; |
+ uint16_t gamma_table_uint[256]; |
+ uint16_t i; |
+ uint16_t *inverted; |
+ int inverted_size = 256; |
+ |
+ compute_curve_gamma_table_type_parametric(gamma_table, trc->parameter, trc->count); |
+ for(i = 0; i < 256; i++) { |
+ gamma_table_uint[i] = (uint16_t)(gamma_table[i] * 65535); |
+ } |
+ |
+ //XXX: the choice of a minimum of 256 here is not backed by any theory, |
+ // measurement or data, howeve r it is what lcms uses. |
+ // the maximum number we would need is 65535 because that's the |
+ // accuracy used for computing the pre cache table |
+ if (inverted_size < 256) |
+ inverted_size = 256; |
+ |
+ inverted = invert_lut(gamma_table_uint, 256, inverted_size); |
+ if (!inverted) |
+ return false; |
+ compute_precache_lut(output, inverted, inverted_size); |
+ free(inverted); |
+ } else { |
+ if (trc->count == 0) { |
+ compute_precache_linear(output); |
+ } else if (trc->count == 1) { |
+ compute_precache_pow(output, 1./u8Fixed8Number_to_float(trc->data[0])); |
+ } else { |
+ uint16_t *inverted; |
+ int inverted_size = trc->count; |
+ //XXX: the choice of a minimum of 256 here is not backed by any theory, |
+ // measurement or data, howeve r it is what lcms uses. |
+ // the maximum number we would need is 65535 because that's the |
+ // accuracy used for computing the pre cache table |
+ if (inverted_size < 256) |
+ inverted_size = 256; |
+ |
+ inverted = invert_lut(trc->data, trc->count, inverted_size); |
+ if (!inverted) |
+ return false; |
+ compute_precache_lut(output, inverted, inverted_size); |
+ free(inverted); |
+ } |
+ } |
+ return true; |
+} |
+ |
+ |
+static uint16_t *build_linear_table(int length) |
+{ |
+ int i; |
+ uint16_t *output = malloc(sizeof(uint16_t)*length); |
+ if (!output) |
+ return NULL; |
+ |
+ for (i = 0; i < length; i++) { |
+ double x = ((double) i * 65535.) / (double) (length - 1); |
+ uint16_fract_t input = floor(x + .5); |
+ output[i] = input; |
+ } |
+ return output; |
+} |
+ |
+static uint16_t *build_pow_table(float gamma, int length) |
+{ |
+ int i; |
+ uint16_t *output = malloc(sizeof(uint16_t)*length); |
+ if (!output) |
+ return NULL; |
+ |
+ for (i = 0; i < length; i++) { |
+ uint16_fract_t result; |
+ double x = ((double) i) / (double) (length - 1); |
+ x = pow(x, gamma); //XXX turn this conversion into a function |
+ result = floor(x*65535. + .5); |
+ output[i] = result; |
+ } |
+ return output; |
+} |
+ |
+void build_output_lut(struct curveType *trc, |
+ uint16_t **output_gamma_lut, size_t *output_gamma_lut_length) |
+{ |
+ if (trc->type == PARAMETRIC_CURVE_TYPE) { |
+ float gamma_table[256]; |
+ uint16_t gamma_table_uint[256]; |
+ uint16_t i; |
+ uint16_t *inverted; |
+ int inverted_size = 4096; |
+ |
+ compute_curve_gamma_table_type_parametric(gamma_table, trc->parameter, trc->count); |
+ for(i = 0; i < 256; i++) { |
+ gamma_table_uint[i] = (uint16_t)(gamma_table[i] * 65535); |
+ } |
+ |
+ //XXX: the choice of a minimum of 256 here is not backed by any theory, |
+ // measurement or data, however it is what lcms uses. |
+ // the maximum number we would need is 65535 because that's the |
+ // accuracy used for computing the pre cache table |
+ inverted = invert_lut(gamma_table_uint, 256, inverted_size); |
+ if (!inverted) |
+ return; |
+ *output_gamma_lut = inverted; |
+ *output_gamma_lut_length = inverted_size; |
+ } else { |
+ if (trc->count == 0) { |
+ *output_gamma_lut = build_linear_table(4096); |
+ *output_gamma_lut_length = 4096; |
+ } else if (trc->count == 1) { |
+ float gamma = 1./u8Fixed8Number_to_float(trc->data[0]); |
+ *output_gamma_lut = build_pow_table(gamma, 4096); |
+ *output_gamma_lut_length = 4096; |
+ } else { |
+ //XXX: the choice of a minimum of 256 here is not backed by any theory, |
+ // measurement or data, however it is what lcms uses. |
+ *output_gamma_lut_length = trc->count; |
+ if (*output_gamma_lut_length < 256) |
+ *output_gamma_lut_length = 256; |
+ |
+ *output_gamma_lut = invert_lut(trc->data, trc->count, *output_gamma_lut_length); |
+ } |
+ } |
+ |
+} |