To optimise your images you'll need to consider the final size your images will be used at. Photographs should be 300-350dpi at the size you are going to use them. There’s no point taking a postage stamp sized image at 300dpi and then blowing it up to a A4 size. Conversely, photographs at more than 350dpi will have no effect on the actual printed quality and will unnecessarily increase file size and
processing time.

Image settings for best results

• All images should be converted to CMYK, and then saved as psd TIFF or JPEG files;
• Photos should be scanned at 300dpi at 100% size;
• Line-art images should be scanned at 800 to 1200dpi at
  100% size;
• TIFF and EPS files are saved without any image compression (not JPEG, LZW or ASCII encoded);
• Any extra alpha channels are removed;
• Ink coverage below total ink limit.