In many places you're able to drop off your camera's memory card just as you used to drop off a roll of film. However, when a local service isn't available, or isn't convenient, you can use one of the many on-line photo finishing services such as Shutterfly or Snapfish. Photo sharing (discussed in the previous chapter) is often combined with photo printing on the same site. The hope is that once you upload images for sharing, you or you visitors might also want to order prints. Not only will these services print your images on traditional photographic paper at sizes ranging from stickers to posters, they'll also put them on mugs, t-shirts, and practically any other item you can think of.

On-line Printers

Most printers used for printing photographs at home are inkjets that are a far cry from the traditional photographic printing technologies that use light to expose silver-halide photographic paper. But the old darkroom technology of exposing, developing, stopping, fixing and drying prints that's been used for decades isn't dead, not even in the digital world. These on-line services expose digital images on traditional photographic paper using a number of different technologies including those that expose the paper with red, green and blue LEDs or lasers. After the exposure, the paper is chemically processed just like in the old days. The result is a photo quality image that's long-lasting and less expensive than many other high-quality digital printing methods.

Print Sizes

It's generally accepted that an image is best when printed at between 200-300 pixels per inch. This means to get a 7 x 5 image, your image should have at least 1500 x 1000 pixels although some subjects let you get away with less. At 150 ppi, most images will appear soft. As the ppi increases above 200 improvements become smaller, and improvements are usually unnoticeable above 300 ppi. When calculating acceptable print sizes, be sure to take any cropping into account because it lowers an image's pixel count.

Whoever says "size doesn't count" wasn't referring to photos. There is nothing quite so stunning as a photo enlarged to poster size except perhaps one enlarged for a billboard or the side of a van. At home, most affordable desktop printers will make borderless prints up to 13 x 19 inch (329 x 483mm). That's the size of a small poster. You can create larger posters as "tiles" on your desktop printer. Bob Bedoll's Poster program (poster.com) can print photographs up to 100 feet square by printing each tile on its own 8.5" x 11" sheet of paper. When assembled, the individual printouts create a giant poster.

Large prints are printed on large format printers. For example, Apple will print images up to 20 x 30 inches in size. These printers use large rolls of paper and are either inkjets or print on traditional silver-halide photographic paper. Some inkjets can even print on waterproof materials suitable for outdoor display. To add text to a poster, or to create a poster with multiple images on it, you use a photo-editing or desktop publishing program.

Things to Consider

When getting images ready to upload, there are a few things to think about:

• Check the Website for information about what you need to do to get the best possible results.
• Upload the largest possible image even though it may take longer. The larger the file the service has to work from, the better the printed image is likely to be.
• Use the correct image format. If you are using a format other than JPEG you should check that the service accepts it. If not, you can use a photoediting program to convert your image to JPEG, or find a service that accepts the format you want to use.
• Use the correct color space. Almost all printers expect images to have the sRGB color space attached. If images have Adobe RGB or ProPhoto color spaces, colors in prints will appear washed out.
• Minimize compression effects. One problem with JPEG images is their compression artifacts. If you send an image as it comes right out of the camera, everything is fine. However, if you edit the image in any way, and then save your changes, the image is compressed again and you lose some image quality. To avoid this, save edited images in PSD, TIFF or other lossless formats as you work on them and only save the final version as a JPEG. No matter which approach you use there is also a slight possibility that you will loose some Exif information that the printer needs to get the best results.
• Minimize cropping. Cropping can be a problem because the aspect ratio of most images differs from that of standard paper sizes. The on-line printing service will often fill the paper, but to do so, some of the image has to fall off the sides and not be printed. To minimize cropping, be sure your photo is the proper aspect ratio before uploading it for printing—in other words, crop it yourself.
• Editing. Most digital images benefit greatly from sharpening, a procedure that is done using a photo-editing program. Many also benefit from adjusting the tonal range. If you don't do these things before uploading images, you may not get the best possible prints. On the other hand the Web site may also be adjusting your images so see what the site says about changes you should and should not make.
• Ask about instore pickup. A number of services have arrangements with chains so you can order on-line but then pick up your images at a local store.