One of the best things about iPhoto is its friendly interface, so even a complete newcomer to the system won't have much trouble editing with iPhoto. Still, there are some tips and hints to keep in mind that will make your life much easier as you groom your photos to look their best!
Once you've selected the photo you want to work on, click "Edit."
You'll get a larger view of that photo. You can adjust the size of the photo with the bar in the lower right hand corner, which people sometimes miss. It allows you to zoom in on an area of the picture, make the whole thing smaller, or enlarge it significantly. This doesn't change the size of the photo itself, only the amount of space you have to work with.
When editing with iPhoto, you can work with up to eight photos at a time (although it's not recommended as they'll appear quite small). To do this, pick one of the pictures you want to work with and enter into the edit mode. The other photos in your library will appear in a bar at the top of the window. Hold down the apple key and select the other photos you want to work with. They will appear in a staggered view in the main window.
IPhoto has a handy little "enhance" key at the bottom of the window. This function does exactly what it sounds like: it enhances the colors and edges in your photo.
The photo on the bottom is an enhanced version of the photo on the top. Most of the time, you'll want to enhance your photos. However, some pictures -- especially those taken with limited light -- can acquire a grainy look when you enhance them. If that happens, use the fail safe when editing with iPhoto: select undo from the edit menu. Also, notice that the enhancement doesn't fix things like red eye: it just brightens things up.
The red eye reduction is simple enough: just click the center of the area you want to tone down. Click as many times as needed, but if you overdo it, the surrounding color will lose all tone (in which case you can resort to that "undo" function again). Notice that some types of red eye just can't be fixed. If it looks more like the white light at the end of the proverbial tunnel than a simple red gleam, you're probably stuck with it.
And there you have it: the four basic functions for editing with iPhoto!
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