Images for printing on press:
RASTER images (working in Photoshop):
- Ask for original images.
- Request .tiff, .raw, or .psd files. Generally, .jpg and .png files can work, but ONLY if their resolution is good. Avoid.gif. files. An original .jpg straight from the camera is preferred, as long as it is not compressed too much. A very compressed .jpg results in artifacts, banding, or other undesirable issues. Try to get the original image. Never edit and re-save .jpg images as .jpg, every time you do you are adding more artifacts and losing color and image fidelity.
- Review for quality.
- Ideal image dimensions Rez min: 250dpi + at dimension(s) in inches/cm it will need to print. File size is not always an accurate measure, but anything under 500k is usually unusable.
- Typically used color profiles (check with your printer, some offer custom profiles for their presses):
- U.S. Web Coated (SWOP) v2 for Magazines
- ISOnewspaper30v4GCR4 for NYTimes newsprint
- US Newsprint (SNAP 2007) for Generic newsprint
- U.S. Sheetfed Coated (SWOP) v2 for packaging and brochures
- U.S. Sheetfed Uncoated (SWOP) v2 for packaging and brochures
- Total ink coverage: Using the Info palette in Photoshop select panel options and Total Ink. Check denser areas of image. Add C+M+Y+K, for Newsprint and if the sum is more than 240, then it may be too much ink. Magazine paper can handle 280-300 or even higher if it is high quality. Usually applying a color profile as a final step will fix these issues. Check with your printer for their press specs.
- Do NOT multiply too many layers in PS … this can result in creating colors that are unprintable (see 8). If you do work this way, then as a final step, create a final flattened file and merge the layers, then apply the appropriate color profile.
- Change images with 16 bits/channel down to 8 before sending to press.
- Adjust colors using Levels or Curves in adjustment Layers.
- Avoid using Brightness/Contrast … Levels or Curves are far superior for adjusting contrast. They can also be used to adjust color channels separately.
- The major issues with Newsprint involve the lower end of mid-tones … simply making whiter whites and darker darks does not make it better.
VECTOR images (working in Illustrator):
- Unless printing SPOT colors, convert them to CMYK.
- Convert RGB to CMYK.
- Be sure white is NOT set to overprint.
- Colors can be set to overprint if you want that effect of transparency. Edges of shapes can be set to overprint for trapping.
- If printing BW, be sure that black is NOT a Rich Black (built of CMYK).
- Be sure there are no embedded or raster images.