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Modernize random_color_transform (#2665) 

* Modernize random_color_transform

* Remove temporary variables

* formatting
This commit is contained in:
Adrià Arrufat 2022-09-10 08:31:19 +09:00 committed by GitHub
parent e50987df4d
commit 19507d4a00
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1 changed files with 13 additions and 16 deletions
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29
dlib/image_transforms/random_color_transform.h
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@ -23,44 +23,41 @@ namespace dlib
const double color_magnitude = 0.2
)
{
// pick a random gamma correction factor.
double gamma = std::max(0.0, 1 + gamma_magnitude*(rnd.get_random_double()-0.5));
// pick a random gamma correction factor.
const double gamma = std::max(0.0, 1 + gamma_magnitude*(rnd.get_random_double() - 0.5));
// pick a random color balancing scheme.
double red_scale = 1-rnd.get_random_double()*color_magnitude;
double green_scale = 1-rnd.get_random_double()*color_magnitude;
double blue_scale = 1-rnd.get_random_double()*color_magnitude;
const double m = 255*std::max(std::max(red_scale,green_scale),blue_scale);
double red_scale = 1 - rnd.get_random_double() * color_magnitude;
double green_scale = 1 - rnd.get_random_double() * color_magnitude;
double blue_scale = 1 - rnd.get_random_double() * color_magnitude;
const double m = 255 * std::max({red_scale, green_scale, blue_scale});
red_scale /= m;
green_scale /= m;
blue_scale /= m;
// Now compute a lookup table for all the color channels. The table tells us
// what the transform does.
table.resize(256*3);
table.resize(256 * 3);
unsigned long i = 0;
for (int k = 0; k < 256; ++k)
{
double v = 255*std::pow(k*red_scale, gamma);
table[i++] = (unsigned char)(v + 0.5);
table[i++] = static_cast<unsigned char>(255 * std::pow(k * red_scale, gamma) + 0.5);
}
for (int k = 0; k < 256; ++k)
{
double v = 255*std::pow(k*green_scale, gamma);
table[i++] = (unsigned char)(v + 0.5);
table[i++] = static_cast<unsigned char>(255 * std::pow(k * green_scale, gamma) + 0.5);
}
for (int k = 0; k < 256; ++k)
{
double v = 255*std::pow(k*blue_scale, gamma);
table[i++] = (unsigned char)(v + 0.5);
table[i++] = static_cast<unsigned char>(255 * std::pow(k * blue_scale, gamma) + 0.5);
}
}
rgb_pixel operator()(rgb_pixel p) const
{
p.red = table[(unsigned int)p.red];
p.green = table[(unsigned int)p.green+256];
p.blue = table[(unsigned int)p.blue+512];
p.red = table[static_cast<unsigned int>(p.red)];
p.green = table[static_cast<unsigned int>(p.green + 256)];
p.blue = table[static_cast<unsigned int>(p.blue + 512)];
return p;
}