GammaFunctor< PixelType > Class Template Reference

Perform gamma correction of an image. More...

#include <vigra/transformimage.hxx>

Public Types
typedef PixelType	argument_type
typedef PixelType	result_type
typedef PixelType	value_type

Public Member Functions
	GammaFunctor (double gamma, argument_type const &min, argument_type const &max)
result_type	operator() (argument_type const &v) const

Detailed Description

template<class PixelType>
class vigra::GammaFunctor< PixelType >

Perform gamma correction of an image.

This functor applies a gamma correction to each pixel in order to modify the brightness of the image. Gamma values smaller than 1 will increase image brightness, whereas values greater than 1 decrease it. A value of gamma = 1 will have no effect. (See also BrightnessContrastFunctor, which additionally changes the contrast.)

For RGBValue's, the transforms are applied component-wise. For ease of use, the pixel values are assumed to lie between the given minimum and maximum values (in case of RGB, this is again understood component-wise). In case of unsigned char, min and max default to 0 and 255 respectively. Precisely, the following transform is applied to each PixelValue:

If the PixelType is unsigned char, a look-up-table is used for faster computation.

Traits defined:

FunctorTraits::isUnaryFunctor is true (VigraTrueType)

Usage:

#include <vigra/transformimage.hxx>
Namespace: vigra

vigra::BImage bimage(width, height);
double gamma;
...
vigra::transformImage(srcImageRange(bimage), destImage(bimage),
   vigra::GammaFunctor<unsigned char>(gamma));



vigra::FImage fimage(width, height);
...

vigra::FindMinMax<float> minmax;
vigra::inspectImage(srcImageRange(fimage), minmax);

vigra::transformImage(srcImageRange(fimage), destImage(fimage),
   vigra::GammaFunctor<float>(gamma, minmax.min, minmax.max));

Required Interface:

Scalar types: must be a linear algebra (+, - *, NumericTraits), strict weakly ordered (<), and pow() must be defined.

RGB values: the component type must meet the above requirements.

Member Typedef Documentation

typedef PixelType argument_type

the functor's argument type

typedef PixelType result_type

the functor's result type

typedef PixelType value_type

Deprecated:

use argument_type and result_type

Constructor & Destructor Documentation

GammaFunctor	(	double	gamma,
		argument_type const &	min,
		argument_type const &	max
	)

Init functor for argument range [min, max]. gamma values < 1 will increase brightness, > 1 will decrease it (gamma == 1 means no change).

Member Function Documentation

result_type operator()

(

argument_type const &

v

)

const

Calculate modified gray or color value

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The documentation for this class was generated from the following file:

• vigra/transformimage.hxx