Sharpening an image

Once you have a CMYK image at the size you’ll be using,  you can apply a little sharpening to punch it up. Make sure you are looking at your image at 100% (View menu / Actual Pixels). Go to Filter > Sharpen  (the flyout gives you several pre-set sharpening options as well as Smart Sharpen in CS2 and CS3) and select Unsharp Mask. Unsharp Mask enhances the edges of an image by making the dark edge darker and the light edge lighter.

Photoshop file size

The size is determined by the resolution x the dimensions of your document x the color space. So a 300 dpi image will be over 4 times bigger than a 72 dpi image, a CMYK image will be four times bigger than a Grayscale image and 25% bigger than RGB. The Help Center at Best Printing Online has an excellent article on resolution and it's affect on image quality

Fast Clean-up Brush for Images

Especially on scanned images, you can get a lot of white specs showing up on the dark areas. It'll take forever to go over the image and clone them out and the Dust & Scratches filter is just too destructive to the rest of the image. Here's how to load a History Brush that will quickly clean up the image and leave the background texture intact.