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Resize photos for the web (cont)
By Uncle Frank
Quality and image compression
There's an easy solution, though. When you alter an image in Photoshop and try to save it, the program first asks you to name the file, and then asks you to specify [jpeg options]. It allows you to select the "quality" of the file by moving a slider to set a number ranging between 0 (lowest quality) and 12 (highest quality). At the bottom of that screen, it actually predicts the file size that will result from the degree of compression you choose.
Nobody wants to show a poor quality picture, but guess what? Quality is used in a different sense when it comes to image files. It refers to how much the file will be "compressed". A large quality number means little compression, and a small quality number means a lot of compression.
Below are sections of my huge picture, which was downsized to 640X480, at several different "quality" levels. Let's see if you can spot a significant difference between them.
 |  |  |
| Compress level 10 (275KB) See original | Compression level 6 (155KB) See original | Compression level 4 (117KB) See original |
Now I've got "senior" eyes but, for purposes of sharing a picture with friends on their computer screens, I don't see much difference at all.
Easy to see; quick to download
My approach is to downsize pictures to 640 pixels in the largest direction, and then to select a level of quality/compression that will result in a file in the range of 100KB. That makes them easy to see, and quick to download. I hope you'll consider doing the same; it's good Netiquette. Happy shooting.
Deer photograph and text: Copyright 2003 Uncle Frank All rights reserved
