Let's say you want to print a photo in a card, calendar, or book, on your printer, or via Apple's online print service, but iPhoto is displaying a warning icon on the page thumbnail, on the preview in the Print dialog, or next to a specific size you want in the Order Prints window. What can you do to resolve this situation?
Ways to handle warning icons:
You can simply print at a smaller size. When printing photos and ordering prints, try a smaller size (Figure 9.1); with a card, calendar, or book, choose a different page design or rearrange the photos so the offending one prints at a smaller size (Figure 9.2). Or, don't zoom into it as far.
Figure 9.1. Note how the three images showing here have warning icons applied to different print sizes. The first (heavily cropped) image can print well only at wallet size. The second (slightly cropped) won't print well at 8" x 10" or larger. The third image (uncropped) drops out at 16" x 20".
Figure 9.2. Note how all these photos, which were taken with my old QuickTake 100 at 640 x 480 pixels, show low-resolution warning icons except the two smaller photos in the three-up page design. A 640 x 480 image must be quite small to print acceptably.
If the photo is too small because you cropped it, you can select it, choose Revert to Original from the Photos menu, and crop it again to a larger size. I recommend this procedure primarily if you think you're right on the edge of receiving the warning icon.
You can also increase the size of your image using GraphicConverter or Adobe Photoshop. The way these programs scale the photo up might look better than iPhoto's method, though it's harder.
For exact details about how many pixels photos must have to print at different sizes, see "Preparing to Order Prints" in Chapter 6, "Printing Photos."
To learn how image resolution relates to what comes out of a printer, take a look at "Understanding Resolution" in Appendix A, "Deep Background."