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Imagick::brightnessContrastImage — Description
$brightness
   , string $contrast
   [, string $CHANNEL = Imagick::CHANNEL_DEFAULT
  ] )Change the brightness and/or contrast of an image. It converts the brightness and contrast parameters into slope and intercept and calls a polynomical function to apply to the image.
brightness
contrast
CHANNEL
Example #1 Imagick::brightnessContrastImage()
<?php
function brightnessContrastImage($imagePath, $brightness, $contrast, $channel) {
    $imagick = new \Imagick(realpath($imagePath));
    $imagick->brightnessContrastImage($brightness, $contrast, $channel);
    header("Content-Type: image/jpg");
    echo $imagick->getImageBlob();
}
?>