Question

I need to take a photo someone has uploaded through a form, resize, merge with a high-res frame @ 300dpi and keep it all @ 300dpi for the best quality for print.

is it possible to handle high-res images through GD and if so, could you provide some information on how? I have code that already does the resizing and merging, but i’m not sure if its going to work at the correct dpi.

Thanks

Answer 1

It’s basically possible: Just use the proper amount of pixels. (The dpi unit has no meaning in digital imaging, it serves only to convert a digital [pixel] image into a physical format).

Example:

11 x 8 inch canvas @300 dpi = 3300 x 2400 pixels 

However, you’ll need plenty of memory to deal with images this large. The rule of thumb is

needed bytes = width x height x 3 (or 4 if alpha-channels are used)

this requirement increases if you do copying or resizing, because the script needs to keep multiple copies in memory.

You will need a very generous memory_limit setting for this to work.

Also note that GD can only deal with RGB images.

For large images and CMYK data, ImageMagick may be a better option if you can use it on your server.