int IMAPI ImgContrast ( hImage, iPercentage, iMedian, iChannel )

This function adjusts the color contrast of an image.

 

Parameter	Type	Description
hImage	HANDLE	Identifies the image to be adjusted.
iPercentage	int	Percentage of color differences to adjust the image by.
iMedian	int	Median value from which to base the color differences.
iChannel	int	Specific color channel to apply the contrast.

 

Valid values for the iChannel parameter are:

 

Value	Description
RGB_RED	adjust the red channel
RGB_GREEN	adjust the green channel
RGB_BLUE	adjust the blue channel
RGB_ALPHA	adjust the alpha channel
RGB_FULL	adjust all the channels

 

 

Return Value

The return value is IMG_OK if the function was successful. Otherwise, it returns IMG_ERR.

 

Comments

This function only operates on 24 bit color images.

 

Specify -1 as the median to use a histogram generated median value. It is better to let the function use a histogram median value since this value is representative of the actual image color content.

 

 

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