Digital cameras usually store pictures in JPEG format, which also happens to be the standard format for displaying images on the Web. The JPEG format allows you to change the compression of the pictures you take.

This setting offers another trade-off between the quality of the pictures and the number of pictures you'll be able to fit on a single memory card. Compression discards some of the information in a digital photo (in effect some of the pixels) to reduce its size, while trying to retain enough of the information so the quality of the photo is still high.

Thus with higher compression, you'll be able to take more photos on a memory card, but the quality of those pictures will be somewhat diminished.

Setting Compression on the Rebel

Both resolution and compression are set through the same interface on the Rebel (see Setting Resolution). Each image size on the menu is a row, and each row is comprised of two columns. Use the left column option for Fine compression at that size, or the right column option for Medium compression. As with all menus, use the arrow keys to navigate and the SET button make a selection.

Setting Compression on the G1

On the Canon PowerShot G1, set the compression through the menu. On the back of the camera, push the MENU button. The menu will be displayed in the LCD screen. Be sure the red Rec menu is highlighted. Then use the Omni Selector dial, the gray button with four arrows that's on the back top right of the camera, to navigate through the menu. Press on the downward pointing arrow on the Omni Selector until the Compression settings line is highlighted. Then press the right or left arrows on the Omni Selector dial to move between and select one of the three icons that represent different settings:

• The first S setting (Superfine) - for the least compression (and hence the highest quality photos, but the fewest photos per card)
• The middle setting (Fine), which is recommended
• The last setting (Normal), which has the most compression (and hence the most possible photos per card, but of the lowest quality)

To retain your selection and leave the menu, press the MENU button again.

Setting Compression on the G5 and Pro 1

On the PowerShot G5 and Pro1, press the FUNC button and use the downward pointing arrow on the Omni Selector to scroll down to the second item from the bottom.

Then press the right or left arrows on the Omni Selector dial to move between and select one of the three icons that represent different settings. The compression options are the same as for the G1.

To retain your selection and leave the menu, press the FUNC button again.