Crop an image automatically using one of the available modes

Description

resource imagecropauto ( resource $image [, int $mode = -1 [, float $threshold = .5 [, int $color = -1 ]]] )

Automatically crops an image according to the given mode.

Parameters

image

An image resource, returned by one of the image creation functions, such as imagecreatetruecolor().

mode

One of the following constants:

IMG_CROP_DEFAULT: Attempts to use IMG_CROP_TRANSPARENT and if it fails it falls back to IMG_CROP_SIDES.
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.

color

Either an RGB color value or a palette index.

Used only in IMG_CROP_THRESHOLD mode.

Return Values

Returns a cropped image resource on success or FALSE on failure. If no cropping would occur, or the complete image would be cropped, that is treated as failure, i.e. imagecrop() returns FALSE.

Examples

Example #1 Proper handling of auto-cropping

As noted in the return value section, imagecropauto() returns FALSE when there is either nothing to crop or the whole image would be cropped. In this example we have an image resource $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 ($cropped !== false) { // in case a new image resource was returned
    imagedestroy($im);    // we destroy the original image
    $im = $cropped;       // and assign the cropped image to $im
}
?>