Are there image processing libraries for PHP that'd allow manipulating images on a pixel by pixel basis like MATLAB?

Question

I'm working on a project that might require me to compute the DCT of the image. Hence the question.

Answer 1

-> Is there a fast way of pixel-by-pixel proceccing images in PHP

I think it would be best to process the files using another language instead of PHP or library/application such as - ImageMagick php.net/manual/en/book.imagick.php. I've never used this myself, so don't really know performance issues. Also -> wideimage.sourceforge.net/ The GD functions, as described in the previous answer, are quite slow, and sometimes can take a huge chunk of the CPU for processing.

Take a look here for seperate benchmarks etc: http://kore-nordmann.de/blog/comparison_of_php_image_libraries_update.html

Answer 2

GD has per-pixel operations, but they're not particularly fast: imagecolorat() and imagesetpixel()