(PHP 5 >= 5.1.0, PHP 7)
Apply a 3x3 convolution matrix, using coefficient and offset
bool imageconvolution ( resource $image, array $matrix, float $div, float $offset )
Applies a convolution matrix on the image, using the given coefficient and offset.
Parameters:
image
An image resource, returned by one of the image creation functions, such as imagecreatetruecolor().