DJ Mike's Tutorials: PHP

Imagick Functions

Imagick::gammaImage

Description:

bool Imagick::gammaImage ( float $gamma [, int $channel ] )

Gamma-corrects an image. The same image viewed on different devices will have perceptual differences in the way the image's intensities are represented on the screen. Specify individual gamma levels for the red, green, and blue channels, or adjust all three with the gamma parameter. Values typically range from 0.8 to 2.3.

Parameters:

gamma

The amount of gamma-correction.

channel

Provide any channel constant that is valid for your channel mode. To apply to more than one channel, combine channeltype constants using bitwise operators. Defaults to Imagick::CHANNEL_ALL.

Channel constants:

imagick::CHANNEL_UNDEFINED
imagick::CHANNEL_RED
imagick::CHANNEL_GRAY
imagick::CHANNEL_CYAN
imagick::CHANNEL_GREEN
imagick::CHANNEL_MAGENTA
imagick::CHANNEL_BLUE
imagick::CHANNEL_YELLOW
imagick::CHANNEL_ALPHA
imagick::CHANNEL_OPACITY
imagick::CHANNEL_MATTE
imagick::CHANNEL_BLACK
imagick::CHANNEL_INDEX
imagick::CHANNEL_ALL

Return Values

Returns TRUE on success.

Errors/Exceptions

Throws ImagickException on error.

Example

<?php
$image = new Imagick("opossum.jpg"); 
$image->gammaImage( 1.25, imagick::CHANNEL_RED );
header("Content-type: image/jpeg");
echo $image;
?> 

^

Created by DJ Mike from Santa Barbara