JPEG The imaging and Web standard

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Pronounced jay-peg, this format is the default setting on your Canon, as it is for most digital cameras. JPEG is popular for two main reasons:

l Web compatibility: All Web browsers and e-mail programs can display JPEG files, so you can share them online immediately after you shoot them.

l Small files: JPEG files are smaller than those produced by the other common format offered by today's digital cameras, known as Camera Raw, or just Raw. And smaller files means that your pictures consume less room on your camera memory card and in your computer's storage tank.

The downside — you knew there had to be one — is that JPEG creates smaller files by applying lossy compression. This process actually throws away some image data. Too much compression leads to the defects you see in the JPEG Artifacts example in Figure 3-1, near the start of this chapter.

On your camera, the amount of compression that is applied depends on whether you choose a Quality setting that carries the label Fine or Normal. The difference between the two breaks down as follows:

l Fine: At this setting, represented by the symbol you see in the margin here, the compression ratio is 4:1 — that is, the file is four times smaller than it would otherwise be. In plain English, that means that very little compression is applied, so you shouldn't see many compression artifacts, if any.

l Normal: Switch to Norm (for Normal), and the compression ratio rises to 9:1. The chance of seeing some artifacting increases as well. Notice the jaggedy-ness of the Normal icon, shown in the margin here? That's your reminder that all may not be "smooth" sailing when you choose a Normal setting.

For comparison, Figures 3-7 and 3-8 show you the same subject shot at the Large/Fine and Large/Normal settings, along with the respective file sizes that each option produces. (I captured each image at the same resolution so that file type is the only variable.)

When you view the left examples in the comparison figures, you may not see much difference between the images, although the type on the lighter cases looks a little sharper in the Large/Fine example. For most printed photos, in fact, compression defects aren't terribly distinct when the print size is small. But when you enlarge your photos, as I did for the right examples in the figures, the exact nature of the quality loss that occurs with JPEG compression become clearer.

Large/Fine, 3.8MB

Large/Fine, 3.8MB

Figure 3-7: The Fine setting produces very good image quality and reasonable file sizes.

Large/Normal, 2MB

Large/Normal, 2MB

Figure 3-8: Enlarging an image captured at the Normal setting reveals some quality loss.

Figure 3-8: Enlarging an image captured at the Normal setting reveals some quality loss.

Know, too, that compression artifacts usually are significantly easier to spot when you view digital images on a computer monitor. (The print process itself softens some of the compression defects.) Artifacting is also usually more visible in areas of flat color than it is in detailed or textured areas.

For my money, the file size benefit you gain when going from Fine to Normal isn't worth the risk of artifacts, especially with the price of camera memory cards getting lower every day. And of all the defects that you can correct in a photo editor, artifacting is perhaps the hardest to accomplish. So if I shoot in the JPEG format, I stick with Fine.

I suggest that you do your own test shots, however, carefully inspect the results in your photo editor, and make your own judgment about what level of artifacting you can accept. Again, artifacting is often much easier to spot when you view images onscreen than I can reproduce here in print.

If you don't want any risk of artifacting, bypass JPEG altogether and change the file type to Raw, explained next.

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Digital Camera and Digital Photography

Digital Camera and Digital Photography

Compared to film cameras, digital cameras are easy to use, fun and extremely versatile. Every day there’s more features being designed. Whether you have the cheapest model or a high end model, digital cameras can do an endless number of things. Let’s look at how to get the most out of your digital camera.

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Responses

  • Carla
    How do i change my settings to small jpeg on canon rebel xti?
    7 years ago
  • SEMRET
    What are the two jpeg comression ratios offered in a canon eos rebel xs?
    7 years ago

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