Imagick::contrastImage

    (PECL imagick 2, PECL imagick 3)

    Imagick::contrastImage — Change the contrast of the image

    Descrizione

    public Imagick::contrastImage(bool $sharpen): bool

    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.

    Elenco dei parametri

    sharpen

    The sharpen value

    Valori restituiti

    Restituisce true in caso di successo.

    Errori/Eccezioni

    Lancia una ImagickException in caso di errore.

    Esempi

    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();
    }

    ?>

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    User Contributed Notes 3 notes

    up
    3
    removespam dot roland at tannerritchie dot com
    10 years 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);
    }
    }
    }
    }
    ?>
    up
    -4
    xyking
    14 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);
    }
    }
    }
    ?>
    up
    -5
    quickshiftin at gmail dot com
    10 years 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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