As we all know, Aperture provides more than a few tools to adjust an image. But for new users--and especially people new to digital photography--it's tough to know how to start adjusting an image. There are literally books on the topic, but for today, I am going to take you through some basics and a sample image. [Edit: There's also a useful two-part article on understanding Aperture's image adjustments here on Inside Aperture].

The first thing to keep in mind is that no tool can save a bad image. There's no software that can un-blur an out of focus picture or fix an image that is severely under or overexposed (more than 2-3 stops in either direction). The information just isn't there in the original file. And remember, RAW files have more information in them than JPEGs, so we recommend shooting RAW whenever possible so that if you need to adjust the image later on, you have the most data possible.

The second thing is that different images need different adjustments. Some shots are perfect out of the camera and take no time in Aperture. Personally, I strive to take images like that as much of the time as possible--if I take the time when shooting to nail my exposure and composition, I don't have to spend time adjusting the image later. Other times, an image may need a lot of tweaking, and we may even have to combine multiple images to create the image we were trying to capture.

The shot we're going to walk through today is one that's in the middle of the spectrum. This is a shot of kiteboarders racing in San Francisco in front of Alcatraz. In the original image, I like the layout of the kites in front of Alcatraz, but the weather was moderately foggy, so the image is pretty low contrast, it's a bit crooked, and the colors lack any punch. It's also hard to see the kiteboarders because there's so much empty sky and water, but that's just because of the 35mm aspect ratio. This is a shot where it's not that great right out of the camera, but I know I have all the tools I need to go from a good to a great shot.

In Aperture, I like to go from top to bottom in the adjustments HUD. For this image, the first thing I'll do is boost the exposure about half a stop. I noticed in the histogram that the right-most point (the whitest white) was about 2/3 of the way across the histogram, making it appear sort of grayish. By boosting the exposure a little (I didn't make it pure white because I didn't want the white to be blown out), my image already looks a bit less murky.

The next step is Black Point. I'll pull this slider up to pull the left side of my histogram closer to black (from the dark gray it was before). Since I have a number of small regions of darker colors, I'm not going to bring my darkest histogram point completely to black, because in this image, it starts to look like there are black blobs on the image. When using black point, zoom in and check different parts of your image to make sure you're not losing detail and creating black blobs.

Some of you might be wondering why I don't just make a Levels adjustment and drag the two end points towards the center. I've discussed before why I prefer Black Point and Exposure to a levels adjustment, but the short of it is that I often see weird color artifacts with Levels that I don't with this method.

Next, I want to increase the contrast slightly, but since I don't want to make the colors more contrasty, I'm going to use the Definition slider. This punches up the contrast without affecting the color. Already the image is looking a lot better, but I want to add a little more impact (and help the kites stand out) by increasing the color saturation. Rather than using the Saturation slider, which adjusts all the colors equally and sometimes can look a bit fake, I'm going to use the Vibrancy slider. This slider does a really nice job of enhancing colors without feeling too fake (you still need a light touch with it).

Now that I have my exposure just the way I want it, I'm going to bring up the Straighten tool by pressing G and straighten out the horizon. Then, because I really want the focus to be on the kiters and Alcatraz, I'll bring up the crop tool by pressing C. In this case, since I want a non-standard aspect ratio, I uncheck the Constrain checkbox and drag out a panorama crop around the middle of the shot (cropping is why I like shooting with high-resolution cameras--even after cropping, this is still roughly an 8 megapixel image).

Finally, just for a last cleanup step, I bring up the retouch tool, set it to repair, zoom in, and pan around my image, double-checking for any dust to remove. When all is said in done, it took me about 3 minutes to work on this image, and I ended up with this final shot.