Resolution

If your ad contains photos or other raster images, it is important that these images have sufficient resolution. Resolution is a measure of how much detail is contained in an image, and it's commonly measured in dots per inch, or dpi. Resolution should be 300 dpi for raster images (or 1200 dpi for bitmap line art). Images with lower resolution will begin to look blurry or "fuzzy."

Images or logos that come from the web are almost always low-resolution and will not be sufficient for print.

When determining the necessary resolution for an image, you must take into account the final print size. If your image is enlarged in your layout program, its effective resolution will be lowered accordingly! For example, if your image is 2" x 3" and 300 dpi, and its size is then increased to 4" x 6" in Quark (an increase of 200%), the image resolution in the final piece will be cut in half - just 150 dpi. Even though the original image is 300 dpi, it will look fuzzy and poor-quality at this larger size. It's better to find a version of the image that is closer to the size you will need in your layout.

Color Space

Images should be saved in the color space that they are expected to print. For a black & white ad, all images should be in grayscale format. For a four-color ad, any color images should be in CMYK format, not RGB.

Cropping

You can lower the file size of your final ad by ensuring that all images are cropped as close as possible to their final appearance in the ad. For example, if you plan on using only a small section of a photo, crop the photo and save it as a new file, and then place this cropped file into your layout rather than the original.

Image Size

Try to use images in your layout at close to 100% size - in other words, don't enlarge or reduce images a great deal in your layout program. For reasons outlined above (see "Resolution"), enlarging images more than 110-115% will drop their resolution too much for us to accept. Reducing (shrinking) images is inadvisable too, however: Placing a high-resolution image at less than 75% or so will just add unnecessary information and file size to your final file. In this case, it's better to resize the original image to the size you need, save it as a new file, and then place it into your layout at 100% size.