In any case, all pixel fonts and patterns should not be scaled once on the screen.If you happen to do that, an aliasing will be applied and you will loose the pixel aspect.

For example, you have designed a 1600x1200 wallpaper with pixel patterns and pixel fonts. You want to make a 1024x768 version out of it. Don't resample the image with the Image Size function. The way to proceed is to crop a 1024x768 section inside the 1600x1200 one.


You want to scale up your pixel work so as to use it for print. If you use the Image Size function so as to get a higher resolution, an aliasing will be applied during the resizing and you will loose the pixel aspect. It won't work.


Here are my tips :


- Convert your picture from RGB to indexed colors with an exact palette Image>Mode>Indexed color.

- Scale it up with the Image Size function only while under Indexed Color mode. Keep in mind you have to keep a ratio so that proportions remain square (like big mosaic pixels).

- Once you have the wanted image size for your print work, move back to RGB mode.
The drawback of that : Indexed Mode is limited to 256 colors.


Another faster solution is to desactivate the aliasing interpolation of Photoshop. Edit > Preferences > General. Set Image Interpolation from Bicubic to Nearest Neighbor. No aliasing will be applied during resizing but don't forget to remove that when you need photoshop to work fine back with photos and color greedy stuff.


Another quick but handy tip is to zoom your picture in photoshop to a multiple amount (200%,300%...) and simply doing a Print Screen so as to catch the zoomed pixel aspect you wanted.