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    imagecropauto

    (PHP 5 >= 5.5.0, PHP 7, PHP 8)

    imagecropauto — Crop an image automatically using one of the available modes

    Description

    imagecropauto(
        GdImage $image,
        int $mode = IMG_CROP_DEFAULT,
        float $threshold = 0.5,
        int $color = -1
    ): GdImage|false

    Automatically crops an image according to the given mode.

    Parameters

    image

    A GdImage object, returned by one of the image creation functions, such as imagecreatetruecolor().

    mode

    One of the following constants:

    IMG_CROP_DEFAULT
    Same as IMG_CROP_TRANSPARENT. Before PHP 7.4.0, the bundled libgd fell back to IMG_CROP_SIDES, if the image had no transparent color.
    IMG_CROP_TRANSPARENT
    Crops out a transparent background.
    IMG_CROP_BLACK
    Crops out a black background.
    IMG_CROP_WHITE
    Crops out a white background.
    IMG_CROP_SIDES
    Uses the 4 corners of the image to attempt to detect the background to crop.
    IMG_CROP_THRESHOLD
    Crops an image using the given threshold and color.
    threshold

    Specifies the tolerance in percent to be used while comparing the image color and the color to crop. The method used to calculate the color difference is based on the color distance in the RGB(a) cube.

    Used only in IMG_CROP_THRESHOLD mode.

    Note: Before PHP 7.4.0, the bundled libgd used a somewhat different algorithm, so the same threshold yielded different results for system and bundled libgd.

    color

    Either an RGB color value or a palette index.

    Used only in IMG_CROP_THRESHOLD mode.

    Return Values

    Returns a cropped image object on success or false on failure. false is also returned if the whole image was cropped.

    Changelog

    Version Description
    8.0.0 image expects a GdImage instance now; previously, a valid gd resource was expected.
    8.0.0 On success, this function returns a GDImage instance now; previously, a resource was returned.
    7.4.0 The behavior of imagecropauto() in the bundled libgd has been synced with that of system libgd: IMG_CROP_DEFAULT no longer falls back to IMG_CROP_SIDES and threshold-cropping now uses the same algorithm as system libgd.
    7.4.0 The default value of mode has been changed to IMG_CROP_AUTO. Formerly, the default value has been -1 which corresponds to IMG_CROP_DEFAULT, but passing -1 is now deprecated.

    Examples

    Example #1 Proper handling of auto-cropping

    As noted in the return value section, imagecropauto() returns false if the whole image was cropped. In this example we have an image object $im which should be automatically cropped only if there is something to crop; otherwise we want to proceed with the original image.

    <?php
    $cropped     = imagecropauto($im, IMG_CROP_DEFAULT);
    if (    $cropped !== false) { // in case a new image object was returned
    imagedestroy($im); // we destroy the original image
    $im = $cropped; // and assign the cropped image to $im
    }
    ?>

    See Also

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    User Contributed Notes 2 notes

    up
    3
    raphael.deiana
    8 years ago
    In some cases the use of the IMG_CROP_WHITE or IMG_CROP_BLACK does not work. The function returns FALSE. It is best to use the IMG_CROP_THRESHOLD mode and specify the color in fourth argument as in the example below :

    <?php

    $original_img     = imagecreatefromjpeg($image_path);

    // Use this :
    $cropped_img_white = imagecropauto($original_img , IMG_CROP_THRESHOLD, null, 16777215);
    // Rather than :
    $cropped_img_white = imagecropauto($original_img , IMG_CROP_WHITE);

    // AND

    // Use this :
    $cropped_img_black = imagecropauto($original_img , IMG_CROP_THRESHOLD, null, 0);
    // Rather than :
    $cropped_img_black = imagecropauto($original_img , IMG_CROP_BLACK);

    ?>
    up
    0
    pj dot mueller at protonmail dot ch
    2 years ago
    I don’t know why you can’t set the threshold for the four sides filter (IMG_CROP_SIDES) so here’s how to do it manually using the IMG_CROP_THRESHOLD filter instead.

    $threshold = .5;

    $im = imagecreatefromjpeg('somefile.jpg');

    $width = imagesx($im);
    $height = imagesy($im);

    $arr = [
    [0,0],
    [$width-1,0],
    [0,$height-1],
    [$width-1,$height-1],
    ];

    $red = 0;
    $green = 0;
    $blue = 0;

    // grab the colours from all four corners
    foreach( $arr as $arr2 ) {
    $thisColor = imagecolorat($im, $arr2[0], $arr2[1]);

    $rgb = imagecolorsforindex($im, $thisColor);
    $red += round(round(($rgb['red'] / 0x33)) * 0x33);
    $green += round(round(($rgb['green'] / 0x33)) * 0x33);
    $blue += round(round(($rgb['blue'] / 0x33)) * 0x33);
    }

    // and average them
    $red /= 4;
    $green /= 4;
    $blue /= 4;

    $newColor = imagecolorallocate($im, $red, $green, $blue);

    $cropped = imagecropauto($im, IMG_CROP_THRESHOLD, $threshold, $newColor);

    imagejpg($cropped, 'somefile.cropped.jpg');

    imagedestroy($im);
    imagedestroy($cropped);
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