Using Zazzle to print shirts:
We recommend using an sRGB color profile for images;
Zazzle supports images in JPEG, PNG, PDF, and Adobe Illustrator (AI) formats. These formats will produce great quality products as long as the resolution meets or exceeds our recommendations. We support full transparency for PNG, PDF and AI files. This can be especially useful if you are creating a design with multiple overlapping images such as borders to go around your design, or shapes with non-rectangular edges. For PDF and AI formats, we support vector output for most of our products. Please note that within the Zazzle Design Tool, a rasterized (bitmap) version of your vector-file will appear.
A Note About Using Images with the Color White
In any image, there are areas that you may want to be transparent (i.e. the area or background behind it shows through) or areas that you may want to be non-transparent. If you create PNG images with transparency, then those transparency settings will be obeyed. In photos, we would guess that no area should be transparent.
But if you have a JPEG image (or PNG image without transparency), you cannot specify which areas are to be treated as transparent. In that case, we let you specify all white in your image as transparent. To do this, under the "Customize It" tab, please check "show whites in image as transparent" on the image module.