adjust gamma of an image - Maple Help

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ImageTools[Gamma] - adjust gamma of an image

Calling Sequence

Gamma( img, gamma, opts )

Parameters

img

-

Image; image to adjust

gamma

-

realcons; adjustment factor

opts

-

(optional) equation(s) of the form option = value; specify options for the Gamma command

Description

• 

The Gamma command performs a gamma adjustment on an image and returns a new, adjusted image. Gamma is a measure of nonlinearity in the color intensities.

• 

The img parameter is the image to adjust.

• 

The gamma parameter specifies the adjustment.  Any numeric value is allowed, but typical adjustments are in the range 1/4 to 4. Values less than 1 lighten the midtones of the images, whereas values greater than 1 darken the midtones. The black (0.0) and white (1.0) levels are left unchanged.

• 

The correction is made to each color channel separately and is computed by raising each pixel's intensity value to the gamma power.

• 

If the image contains negative intensity values as a result of some previous image processing operation, gamma must be a positive integer. Otherwise, complex values will result and Gamma will return an error message. The Clip or FitIntensity commands can be used to ensure all intensity values are in the 0..1 range.

Examples

imagefile:=catkerneloptsdatadir,/images/fjords.jpg:

withImageTools:

img:=Readimagefile:

lighter:=Gammaimg,0.7:

cannot_gamma:=img0.1:

Gammacannot_gamma,0.7

Error, (in ImageTools:-Gamma) pixel values must be nonnegative with nonintegral exponent

data:=Create0.0,0.2,0.4,0.6,0.8,1.0:

printf%0.3f ,data

0.000 0.200 0.400 0.600 0.800 1.000

darker_data:=Gammadata,1.2:

printf%0.3f ,darker_data

0.000 0.145 0.333 0.542 0.765 1.000

See Also

ImageTools, ImageTools[Clip], ImageTools[FitIntensity]


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