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Changed the brightness and contrast color processing algorithm to match exactly the GIMP algorithm.

This commit is contained in:
Paolo Cignoni 2009-05-25 09:02:32 +00:00
parent 0f4817d486
commit 37057700b2
1 changed files with 14 additions and 7 deletions
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21
vcg/complex/trimesh/update/color.h
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@ -492,8 +492,8 @@ static int ValueMul(int value, float factor)
return math::Clamp<int>((int)((value - 128)*factor + 128), 0, 255);
}
//Apply Contrast and Brightness filter to the mesh, with the given contrast factor and brightness amount.
static int ContrastBrightness(UpdateMeshType &m, float factor, float amount, const bool ProcessSelected=false)
//Apply Brightness and Contrast filter to the mesh, with the given contrast factor and brightness amount.
static int BrightnessContrast(UpdateMeshType &m, float brightness, float contrast, const bool ProcessSelected=false)
{
int counter=0;
VertexIterator vi;
@ -503,7 +503,7 @@ static int ContrastBrightness(UpdateMeshType &m, float factor, float amount, con
{
if(!ProcessSelected || (*vi).IsS()) //if this vertex has been selected, do transormation
{
(*vi).C() = ColorMulAdd((*vi).C(),factor,amount);
(*vi).C() = ColorBrightnessContrast((*vi).C(),brightness,contrast);
++counter;
}
}
@ -513,14 +513,21 @@ static int ContrastBrightness(UpdateMeshType &m, float factor, float amount, con
//Performs contrast and brightness operations on color, i.e NewValue = (OldValue - 128) ◊ contrast + 128 + amount
//The result is clamped just one time after all computations; this get a more accurate result.
static Color4b ColorMulAdd(Color4b c, float factor, float amount)
// The formula used here is the one of GIMP.
static Color4b ColorBrightnessContrast(Color4b c, float brightness, float contrast)
{
return Color4b( ValueMulAdd(c[0], factor, amount), ValueMulAdd(c[1], factor, amount), ValueMulAdd(c[2], factor, amount), 1 );
return Color4b( ValueBrightnessContrast(c[0], brightness, contrast),
ValueBrightnessContrast(c[1], brightness, contrast),
ValueBrightnessContrast(c[2], brightness, contrast), 1 );
}
static int ValueMulAdd(int value, float factor, float amount)
static int ValueBrightnessContrast(unsigned char ivalue, float brightness, float contrast)
{
return math::Clamp<int>((int)((value - 128)*factor + 128 + amount), 0, 255);
float value = float(ivalue)/255.0f;
if (brightness < 0.0) value = value * ( 1.0 + brightness);
else value = value + ((1.0 - value) * brightness);
value = (value - 0.5) * (tan ((contrast + 1) * M_PI/4) ) + 0.5;
return math::Clamp<int>(255.0*value, 0, 255);
}
//Invert the colors of the mesh.