A digital photo of your artwork with a gray scale at your camera's highest quality setting or a digital file sized to 300ppi at desired physical size and saved as a .psd, .tif, .png, or .dng file. Use .jpg only if nothing else is available and re-save the image as few times as possible. Be aware that the file compression used in JPEG format throws away a small amount of "unnecessary" information each time a file is saved. This will begin to show up in larger prints as digital noise (grain or snow) particularly in shadow areas. The gray scale can be placed within a plain background area where we can clone it out or placed next to the art work where it can be cropped out. The gray scale is used to determine the neutral color of an image therefor it is necessary that it is a true photographers gray scale and not one printed with your printer. An alternative would be to create three rectangles along one side of your image (increase your canvas size to fit). Fill one with RGB 255, 255,255 from the "Color Picker". Fill the second rectangle with RGB 128,128,128. Fill the third rectangle with RGB 0,0,0. Flatten the image.

Adobe product screen shot(s) reprinted with permission from Adobe Systems Incorporated.

For color accuracy the monitor you use for preparing the file must be calibrated to ICC standards. Hardware calibration is the most accurate and can be done with a colorimeter or spectrophotometer (X-Rite®, Datacolor®, etc.). If these are not available, software calibration can be done. On Macintosh® computers ColorSync is built into the monitor control panel; on Microsoft Windows® systems if you are using an Adobe® product such as Adobe® Photoshop® or Photoshop® Elements, Adobe® Gamma should also have been installed in your Control Panels or it can be downloaded from the Adobe® website (do a search for "Adobe Gamma"). Note 1: Monitor contrast is usually set to 100% and brightness around 50% or a little above, the older your monitor the brighter it will need to be set. Note 2: If your prints are consistently darker than your display, your monitor is too bright or you may want to try setting the Gray Gamma to 1.8 rather than 2.2 in color settings.
If your image editing software allows you to simulate print output or "softproof" using ICC profiles here are the profiles we use for our most common print media. Download the files and install in your profile library: Mac OS9 and earlier ../system/colorsync/profiles; Mac OSX: ../library/colorsync/profiles or for Adobe apps: ../library/application support/adobe/color/profiles/recommended; Windows XP: C:\WinNT\System32\Spool\Drivers\Color or right-click on the profile and choose "Install Profile". Epson Premier Presentation (Enhanced Matte); Hahnemuhle Photo Rag; Hahnemuhle Photo Rag Bright White; Somerset Velvet; Black Diamond Canvas; AlphaRag White; Polyester FR; Hahnemuhle Fine Art Baryta; Ilford Gloss or Pearl; Blockout Vinyl Scrim; Self Adhesive Polypropylene.