- int const bit_length = pow (2, bit_depth);
- float* lut = new float[int(std::pow(2.0f, bit_depth))];
- for (int i = 0; i < bit_length; ++i) {
- float const p = static_cast<float> (i) / (bit_length - 1);
- if (p > _threshold) {
- lut[i] = pow ((p + _A) / (1 + _A), _power);
- } else {
- lut[i] = p / _B;
+ int const bit_length = int(std::pow(2.0f, bit_depth));
+ double* lut = new double[bit_length];
+ if (inverse) {
+ double const threshold = _threshold / _B;
+ for (int i = 0; i < bit_length; ++i) {
+ double const p = static_cast<double>(i) / (bit_length - 1);
+ if (p > threshold) {
+ lut[i] = (1 + _A) * pow (p, 1 / _power) - _A;
+ } else {
+ lut[i] = p * _B;
+ }
+ }
+ } else {
+ for (int i = 0; i < bit_length; ++i) {
+ double const p = static_cast<double>(i) / (bit_length - 1);
+ if (p > _threshold) {
+ lut[i] = pow ((p + _A) / (1 + _A), _power);
+ } else {
+ lut[i] = p / _B;
+ }