File preperation Guidelines for Photoshop Adobe Photoshop (or any raster-based image capable of being opened in Photoshop) is supported. Raster-based images must be at the exact final desired size with resolution set . Color Guidelines Images should be designed in the RGB color mode. If you attempt to convert a CMYK file to the RGB mode unexpected shifts in color may occur. Always work from the original RGB scan to realize the full color gamut possible. File Size 400 pixels per inch (designing at 400 ppi for 4000 output creates prohibitively large files with no visual improvement in quality. Meg charges will apply.) It is your choice which resolution will work best for your image. Failure to design at the exact print size required if we agree to adjust or resize your file. (Interpolating your image data may affect image quality.) Generally, an image of higher resolution will print sharper than one of lower res but this comes with the burden of being a larger file size as well. Keep in mind that excessive resolution (beyond that recommended results in larger files that take longer to print with little or no visual improvement in print quality.