PHP 7.0.6 Released

    Imagick::contrastImage

    (PECL imagick 2.0.0)

    Imagick::contrastImage — Change the contrast of the image

    Description

    bool Imagick::contrastImage ( bool $sharpen )

    Enhances the intensity differences between the lighter and darker elements of the image. Set sharpen to a value other than 0 to increase the image contrast otherwise the contrast is reduced.

    Parameters

    sharpen

    The sharpen value

    Return Values

    Returns TRUE on success.

    Errors/Exceptions

    Throws ImagickException on error.

    Examples

    Example #1 Imagick::contrastImage()

    <?php
    function contrastImage($imagePath, $contrastType) {
            $imagick = new \Imagick(realpath($imagePath));
        if (    $contrastType != 2) {
                $imagick->contrastImage($contrastType);
        }

            header("Content-Type: image/jpg");
        echo     $imagick->getImageBlob();
    }

    ?>

    User Contributed Notes

    removespam dot roland at tannerritchie dot com
    1 year ago
    Both xyking and quickshiftin include errors in their comments. xyking's error is in looping through negative numbers. quickshifting is incorrect in stating that 0 *increases* contrast (it does not - it decreases it).

    Here is a (tested, working) method to increment or decrement contrast:
    <?php
    class Images {
    public function     contrastImage($contrast, $imagePath){

    $this->image = new Imagick();
    $this->image->readImage($imagePath);                    

    if (    $contrast > 0){
                    for (    $i = 1; $i < $contrast; $i++){
                            $this->image->contrastImage(1);
                    }
                }else if (    $contrast <= 0) {

                    for (    $i = 0; $i > $contrast; $i--) {

                            $this->image->contrastImage(0);
                    }
                }
         }
    }
    ?>
    xyking
    6 years ago
    Tip:
    <?php
    $image    ->contrastImage(1); //Increase contrast once
    $image->contrastImage(1); //Increase contrast more
    $image->contrastImage(1); //Increase contrast even more

    $image->contrastImage(0); //Decrease contrast once
    $image->contrastImage(0); //Decrease contrast more
    $image->contrastImage(0); //Decrease contrast even more

    //This could be made into a function like this:
    public function contrast($level) {
                $level = (int)$level;
            if (    $level < -10) {
                    $level = -10;
            } else if (    $level > 10) {
                    $level = 10;
            }
            if (    $level > 0) {
                for (    $i = 0; $i < $level; $i++) {
                        $this->image->contrastImage(1);
                }
            } else if (    $level < 0) {
                for (    $i = $level; $i > 0; $i--) {
                        $this->image->contrastImage(0);
                }
            }
        }
    ?>
    quickshiftin at gmail dot com
    1 year ago
    xyking's comment is wrong so be careful if you read it. You pass a value of 0 to *increase* the contrast.
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