The following are key elements to address. After choosing the options that fit your business, you can use our Guideline Generator to prepare a document that contains your own custom Digital Image Submission Guidelines.
main principles
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- color management
Both suppliers and receivers of a digital image file need to see the same image. This requires setting systems to display standardized, consistent color, and embedding in images color profiles that describe their color characteristics. (complete guideline) - file size and resolution
File size depends on intended use. As a rule, stock image distributors require the largest file sizes, since final use is unknown. Magazines can be more specific, although they may request Double Page (11 x 17 inches, A3 or 420mm x 297mm) for maximum flexibility in placement and cropping. Graphic designers and advertising art directors should be very specific about file sizes, since it's best for the photographer to deliver files within 10 percent of final size — unless the designer will handle resizing and output sharpening. Designers who do resize images should start with a larger size and reduce it, rather than attempting to increase the resolution of smaller image files. Web use and digital projection require much smaller file sizes. Widescreen HDTV requires 1920 x 1080 pixels for uncropped images. (complete guideline) - delivery file formats
TIFF and JPEG (quality 10 or higher in the Photoshop "Save As" dialog) are usually the preferred file formats for delivery. Be aware that JPEGS saved at anything less than level 12 quality may have compression artifacts that could show up under certain printing conditions, such as the use of stochastic screens. Both are standard formats, universally supported by image-editing and image-cataloging software. And both can safely hold metadata. Be careful about requesting or submitting raw file formats, including DNG files. While they allow a wide range of adjustments, this can lead to final color and tone that differ considerably from what the photographer intended — or the client expects. (complete guideline) - file delivery options
Regardless of format, file extensions are essential. If receiving images on CD-R or DVD-R discs, request them recorded in ISO 9660, cross-platform format. A portable hard drive may be the best tool for delivering large numbers of files, but beware of compatibility issues between Macintosh and Windows file systems. Online delivery via email, FTP or a commercial web delivery service offers an increasingly attractive and viable option. Compressing folders of files in digital wrappers, such as ZIP or SIT archives, helps avoid file corruption. UPDIG recommends requesting "ReadMe" files on all delivery media, listing file characteristics, any special concerns and usage rights. (complete guideline) - icc profiles
There are two primary color modes in use: RGB and CMYK. RGB (Red, Green, Blue) is the standard archival and delivery color space, and holds more color information than CMYK (Cyan, Magenta, Yellow, Black) which is used for print output.
The conversion of an RGB file to CMYK involves a loss of color information tat is not reversible, so in general it is best to retain images in RGB as far as possible in the workflow. CMYK's image files with four channels are 25 percent larger than the equivalent RGB with three channels. Adobe RGB (1998) is the most common delivery standard, with ECI RGB being adopted by some publishers in Europe. Unfortunately, the sRGB color space is probably used more often than either, although its smaller color gamut clips some colors that fall within the gamut of an offset press rendering those otherwise printable colors un-printable.
Color profiles specify which color space the image is in, and should always be embedded in the image when saving, and preserved when opening, for correct viewing and handling. It is impossible to interpret the color numbers in an image correctly and with certainty if the color space is not known. (complete guideline) - sharpening
After resolution and color, sharpening can have the most impact on perceived image quality. Most digital cameras deliver slightly soft images (unless the capture format is set to JPEG or TIFF with in-camera sharpening turned up). This results from the almost universal use of anti-aliasing filters to combat moiré. Scanning camera backs and some medium-format backs — especially those with multi-shot mode may not have this feature. If we assume single-shot raw file capture, it is entirely appropriate to request a small amount of default "capture" sharpening. Without it, digital image files may look too soft.
How and when to add process sharpening and sharpening for output requires clear communication between those requesting digital files, and those creating and delivering digital image files. (complete guideline) - file quality
All images, whether originating from scanner or from digital camera files, need to be processed, but unskilled processing and correction, as well as over-sharpening and over-compression, lead to degradation of image quality. High quality scanners should be used, but image quality will depend as much on scanning and image processing skills as on the technology employed.
Image submissions guidelines are always important, and photographers should work to generally accepted standards if their customer does not supply their own guidelines (link to Digital Image Spec) along with proper quality control. Guides to common image faults may also be useful for suppliers. (complete guideline) - file naming
To avoid problems with files transferred across computing platforms, request file names that use only the letters of the Latin alphabet (A-Z, a-z), the numerals 0 through 9, hyphens and underscores. Avoid other punctuation marks, accented vowels, non-Latin letters or other non-standard characters, such as \:/*<> or brackets. On a local network or with rewritable media, limit the file name to 31 characters or less (including the three-letter file extension. Limit file names to 11 characters or less (including the three-letter file extension) when burning to optical media, since some computers may not support long file names. Use a single period (".") between the file name and extension. Specify unique file names. Multiple files with the same name will cause problems for computers and people alike, and a newer file might automatically overwrite an older with the same name, or vice-versa. You may want to specify including the numeric date and/or the name of the photographer as part of the file name as a way to avoid duplicate names.
For a complete guide to file-naming protocol, see the Controlled Vocabulary website. - metadata
Digital image metadata is information about the image. Information like picture number, caption, credit and copyright that used to be carried on the hard copy, should now be found within the digital file so that images are captioned and can be traced back to their supplier and copyright holder.
Metadata come in many forms and schemas, from EXIF, to ICC profiles, IPTC, XMP and PLUS. Metadata needs vary for stock image distributors, magazines, publishers, print and web designers, and photographers maintaining their own libraries. When requesting or delivering digital image files, understand and use metadata to streamline the production workflow. It's increasingly common for stock-image distributors and magazine publishers to develop custom XMP metadata panels that conform to their particular needs. (complete guideline) - fine art reproduction
Creating and preparing digital reproductions of fine artworks requires all the careful attention to details already presented, but it also poses significant additional challenges. Unlike typical photo reproduction, the colors within digital files of artwork are not subject to interpretation or individual preference. The reproduction must produce the same perceived color (within physical limitations) as the original artwork. (complete guideline)
Stock image distributors have the greatest need to implement their own file naming conventions, followed by magazines and publishers.
For image-file tracking, it's a good idea to ask image creators to include their original file names in Document Title fields (of images' metadata), since many end users change the names associated with files.