imageconvolution() is an inbuilt function in PHP that is used to apply a 3×3 convolution matrix, using the coefficient and offset in the image.
Syntax
bool imageconvolution ( $image, $matrix, $div, $offset)
Parameters
imageconvolution() takes four parameters: $image, $matrix, $div, and $offset.
$image − This parameter is used to create the size of the image by using an image creation function such as imagecreatetruecolor().
$matrix − This parameter contains an array of 3×3 matrix of floats.
$div − It is used for normalization.
$offset − This parameter is used to set the color offset.
Return Values
imageconvolution() returns True on success and False on failure.
Example 1
<?php
// load the PNG image by using imagecreatefrompng function.
$image = imagecreatefrompng('C:\xampp\htdocs\Images\img59.png');
// Applied the 3X3 array matrix
$matrix = array(
array(2, 0, 0),
array(0, -1, 0),
array(0, 0, -1)
);
// imageconvolution function to modify image elements
imageconvolution($image, $matrix, 1, 127);
// show the output image in the browser
header('Content-Type: image/png');
imagepng($image, null, 9);
?>Output
Input PNG image before using imageconvolution() function
Output PNG image after using imageconvolution() function
Example 2
<?php
$image = imagecreatetruecolor(700, 300);
// Writes the text and apply a gaussian blur on the image
imagestring($image, 50, 25, 8, 'Gaussian Blur Text image', 0x00ff00);
$gaussian = array(
array(1.0, 2.0, 1.0),
array(2.0, 4.0, 2.0),
array(1.0, 2.0, 1.0)
);
imageconvolution($image, $gaussian, 16, 0);
// Rewrites the text for comparison
imagestring($image, 15, 20, 18, 'Gaussian Blur Text image', 0x00ff00);
header('Content-Type: image/png');
imagepng($image, null, 9);
?>Output
