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BrightnessContrastFunctor< PixelType > Class Template Reference |
Adjust brightness and contrast 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 | |
BrightnessContrastFunctor (promote_type brightness, promote_type contrast, argument_type const &min, argument_type const &max) | |
result_type | operator() (argument_type const &v) const |
Adjust brightness and contrast of an image.
This functor applies a gamma correction to each pixel in order to modify the brightness of the image. To the result of the gamma correction, another transform is applied that modifies the contrast. The brightness and contrast parameters must be positive. Values greater than 1 will increase image brightness or contrast respectively, values smaller than 1 decrease them. A value of exactly 1 will have no effect. If contrast is set to 1, the result is equivalent to that of the GammaFunctor with gamma = 1./brightness.
For RGBValue's, the transforms are applied component-wise. 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
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.
typedef PixelType argument_type |
the functor's argument type
typedef PixelType result_type |
the functor's result type
typedef PixelType value_type |
BrightnessContrastFunctor | ( | promote_type | brightness, |
promote_type | contrast, | ||
argument_type const & | min, | ||
argument_type const & | max | ||
) |
Init functor for argument range [min, max]
. brightness
and contrast
values > 1 will increase brightness and contrast, < 1 will decrease them, and == 1 means no change.
result_type operator() | ( | argument_type const & | v | ) | const |
Calculate modified gray or color value
© Ullrich Köthe (ullrich.koethe@iwr.uni-heidelberg.de) |
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