10 steps to getting the job done right--the first time!
6. Size & Crop
One of the biggest problems with using an online processor is the time it takes to upload your images. And if you rely on a commercial lab to crop your full-res images to print sizes such as 5x7 or 8x10 inches, you may also have trouble, since they don't match standard sensor (or 35mm film) ratios.
The solution? Crop your images on your computer to match the format for the prints you want. Then, adjust the image file resolution to provide just the right amount of detail, so that your image files transfer or upload quickly. For example, if you want to make an 8x10-inch print (a 4:5 aspect ratio) from a photo taken with a 6MP DSLR (which captures a 2:3 aspect ratio), you'll have to trim it on the long sides or zoom in and then crop.
After cropping, go into the image size dialogue and set the dimensions to 8x10 inches. Next, reduce the file's pixels per inch (in some older programs this may be called dots per inch) to 200-250 ppi. That's all you really need to make a photo-quality print. Higher resolution will inflate the file size and take longer to upload and process at the lab.
Of course, if you cropped tightly or shot with a lower-res digital camera, your ppi setting might be below 200, making for fuzzier prints at that size. (Most online labs now warn you if your file lacks the image resolution for the print size you requested.) In that case, go for a smaller print.
Tip: Nothing slows down a print kiosk like full-resolution images from an 8MP or higher DSLR (especially if you store in RAW + JPEG mode or have the color space set to Adobe RGB). So resize them first and save as JPEG.
7. Don't Squeeze Too Tight
Once image size and resolution are right, it's time to save the images. For best compatibility and faster uploads to an online processor, the JPEG file format is the best choice. (Don't ever send RAW files!) JPEG is a compressed format, with compression levels from very low (about 2:1 ratio) to extreme (50:1).
If you're using Photoshop or Elements, the optimum setting is 8 (high quality, with roughly 7:1 compression). You won't notice JPEG artifacts at this level, and less compression will slow down image transfers and uploads. However, if you're giving a CD-R or memory card to a lab, you can opt for less compression.
In either case, select the "Baseline Standard" method of JPEG compression for the greatest compatibility and image quality, and make sure your file names all have a .jpg extension.