Imagick::contrastImage

    (PECL imagick 2, PECL imagick 3)

    Imagick::contrastImage — 画像のコントラストを変更する

    説明

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

    画像の中の暗めの部分と明るめの部分の輝度の差を強調します。 sharpen に 0 以外を指定すると画像のコントラストを上げ、 0 を指定するとコントラストを下げます。

    パラメータ

    sharpen

    シャープ値。

    戻り値

    成功した場合に true を返します。

    エラー / 例外

    エラー時に ImagickException をスローします。

    例

    例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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