PHP | imageconvolution() Function

Last Updated : 23 Aug, 2019

The imageconvolution() function is an inbuilt function in PHP which is used to modify the image content. It applies a 3 x 3 convolution matrix in the image, using the given coefficient and offset. This function returns true on success or false on failure. Syntax:

bool imageconvolution ( $image, $matrix, $div, $offset )

Parameters: This function accepts four parameter as mentioned above and described below:

$image: It is returned by one of the image creation functions, such as imagecreatetruecolor(). It is used to create size of image.
$matrix: It contains an array of 3 x 3 (3 x 3 matrix) of floats.
$div: It is divisor of result of the convolution, used for normalization.
$offset: It is used to set the color offset.

Return Value: This function returns True on success or False on failure. Below programs illustrate the imageconvolution() function in PHP: Program 1:

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<?php  // Create a gif image  $image = imagecreatefromgif( 'https://media.geeksforgeeks.org/wp-content/uploads/animateImages.gif');   // Declare a 3X3 matrix $matrix = array(         array(2, 0, 0),          array(0, -1, 0),          array(0, 0, -1) );   // imageconvolution function to modify image elements imageconvolution($image, $matrix, 1, 127);   // Output of image content header('Content-Type: image/png'); imagepng($image, null, 9); ?>

Output:

Program 2:

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<?php  // Create a gif image  $image = imagecreatefrompng( 'https://media.geeksforgeeks.org/wp-content/uploads/geeksforgeeks-9.png');   // Declare a 3X3 matrix $emboss = array(                 array(0, -1, 2),          array(2, 0, 0),         array(2, 0, -2) );   // imageconvolution function to modify image elements imageconvolution($image, $emboss, 1, 127);  // Output of image content header('Content-Type: image/png'); imagepng($image, null, 9); ?>