class.upload.php is a powerful and mature PHP class to manage uploaded files, and manipulate images in many ways. The script is available under a GPL license.
more info about the class
image_src_x : 2000
image_src_y : 2791
image_src_pixels : 5582000
image_src_bits : 8
So, 5.582.000x8 = 44.656.000 bits
My PHP memory limit is 128MB... it should be enough, isn't it?
Thanks again!