Digital Files
Most modern print shops are digital and therefore require a digital file to make prints. When it comes to digital file types the single most significant factors are file type, color space, and pixel dimensions.
File Types
The software that I use to run our printers allows for JPEG, TIFF, PNG, PSD file formats. TIFF is always preferred as it uses a lossless compression format which means that it is uncompressed. PSD is another common file type that stands for PhotoShop Document. This file format is capable of storing an image with support for most imaging options available within Photoshop. The downside to the TIFF and PSD file type is the size. TIFFs can be up to a 4GB and PSDs 2GB. JPEG and PNG are file types that are more concerned with file size. They are the most widely used compression formats on the internet. While we prefer maximum quality JPEGs with AdobeRGB(1998) color profile, a TIFF or PSD will certainly suffice. JPEGs are small enough to upload, and they still maintain color quality and resolution even when enlarged. Most print shops prefer JPEGs, and I agree that up to a certain size a JPEG will satisfy most customers. Now if you want to print something 40″ x 60″, then we might want to think about a more robust file format.
Color Space
While file types vary, color space has a much narrower set of options. Although our printers use CMYK ink sets, they are RGB printers. Meaning they prefer file types with an RGB color space. For the best colors, I suggest using the AdobeRGB(1998) color space. AdobeRGB is a color setting used when creating a digital file. Check your camera settings and software settings to embed this color profile in the files you are using. If you are shooting in RAW and are using a RAW editor such as Lightroom, your color space settings are set when you export your file.
Pixel Dimensions
I get asked a lot about how large I can print a file. While file type and color space affect overall quality, the single largest contributor to the size of the print you can make from a file is pixel dimensions. To determine how large of a print you can make from the digital file you need to divide the file’s pixel dimensions by 150. For example, you have an image that is 2400 x 3600 pixels. Divide each number by 150 to get the largest print size you can print. That would make a 2400/150=16 and 3600/150=24. That would mean that you could safely print a 2400 x 3600-pixel file up to a 16″ x 24″ print.
You do not need to enlarge your images. Leave that part up to me and my staff. We need a minimum of 150 pixels per inch to print from, but always prefer more when available.