Recently someone asked about problems with underexposed images on a camera. Sometimes if you are at a gallery reception, messing with the f-stop is too much of a hassle, and the “Auto” setting can result in underexposed images. An excellent way of dealing with the exposure problem is to process the photos on your computer using free image touch-up software.
One program I use often to modify my photos is UFRAW. UFRAW assumes you take your photos in RAW format. It is free on-line, and is a super program. It will lift the exposure and let you modify many other parameters, such as green level and interpolation. It features a live histogram to monitor your changes. RAW format bypasses the camera’s built-in image processing, so you are working with the data directly from the sensor.
Another great program for use with photos is GIMP. I use it all the time. It is free to download (I use it on Linux, so I’m not sure how it works on other platforms – but I have heard from other artists that it works fine). GIMP will do cropping, resolution, resizing, brightness/contrast, animation, special effects, and a zillion other things. It will work in any format including jpg, which is what most cameras use. However, it will not directly work with RAW since RAW is semi-proprietary, but can import RAW using UFRAW.
With these two free software programs, you can do just about anything imaginable with your photos. I know one artist that uses GIMP to create unusual special artistic effects on her photos, which she then sells in galleries and art shows!