Here are two details to be aware of when preparing images for your print project.
First, it’s important to consider the recommendations for image size and resolution. For optimal results, image resolution should be 300 DPI (dots per inch) at the final output size. DPI is often also referred to as Pixels Per Inch (PPI), which is a measurement of resolution of a printed image, determined by the number of printing dots that fit into one inch. Images containing less than 300 dpi print resolution will look good on your computer screen, but may appear blurred or lack detail when printed. Several free graphic editors can resize images to the recommended 300 dpi resolution, such as Preview on the Mac, or the freely downloadable Irfanview for Windows.
When resizing an image for print, take care that you do not also resample the image. The actual pixel dimensions of the image should not change, only the dpi resolution needed for print. For example, an image that is about 7 inches wide with a resolution of 72 ppi, if resized to 300 ppi, will be less than 2 inches wide in print:
Before:After (notice Resample image is not checked):
Second, it’s important to understand the difference between RGB and CMYK color space. High-end graphic programs such as Adobe Photoshop or Illustrator can convert images from RGB to CMYK colorspace using a menu command (choose “Image>Mode>CMYK” or “File>Document color mode>CMYK color”). And, although the consumer-level graphic editors can resize images for resolution, they do not provide the ability to change the colorspace from RGB to CMYK. Once the print resolution of your image is set to 300 dpi, you can use a free online image converter such as http://www.rgb2cmyk.org/ to convert the image to CMYK colorspace for print.
Remember, for best results, images should always be cropped and/or resized, and the colorspace should be converted before inserting or placing in a print project. If you are unsure whether your images will look good in print, consider sending your file to us before you order, for a no-cost or obligation file review.