Which image editing software is effective and useful?
The first thing you want to do with images is to look at them on your big computer monitor, to make sure they are as good as they look in the little camera screen. IrfanView is the most popular free open source image viewer and has some simple options to rotate image. ACDSee is the most popular commercial image viewer and has an image management upgrade.
The next step, when you have lots of images, is to classify them for use. You might put all your family photographs in one directory and all your work photos in another. After a while, you have too many for simple classification by directory. You need to tag images with keywords, by date, and other attributes. ACDSee lets you manage images but only on Windows and only after buying it. F-spot and Shotwell are two free open source alternatives to ACDSee but neither runs on Windows, you need Linux.
Image management software usually lets you correct rotation, convert from RAW, TIFF, and other input formats to common viewable formats, and may provide simple cropping, exposure adjustments, and contrast improvements. The software will usually create a set of thumbnail images for easy viewing. The software should provide one click through to editing in your favourite image editor.
The Gimp is the most widely distributed image editing software because there are no licensing restrictions or export controls to stop people using Gimp. Photoshop is the expensive alternative to Gimp and has some new features before they arrive in Gimp. If you have the very latest, most expensive digital still camera then you probably have Photoshop because Photoshop was the first image editor to edit 12, 14, and 16 bit RAW files.
One reason to buy Photoshop is the huge range of plug in extensions but those plug ins also plug in to Gimp and Paintshop Pro.
Gimp is the only image editor that runs on Windows, Linux, and the Unix used on Apple Macs. If you use Windows now, want to switch to Linux in the future, and occasionally have to work on a customer's Mac OS X then you can switch to Gimp and use the same program on every machine.
CinePaint works on Linux and Unixes, including OS X. CinePaint did have a Windows version then it died and now they are working on a new version of CinePaint that should be compatible with Windows. The big advantage of CinePaint over Gimp is native 16 bit colour. Another advantage is the ease of transition from Gimp to CinePaint because CinePaint started life as a version of Gimp.
If you edit still frames in movies then you will like the frame management in CinePaint. This is not editing video. We are not talking about editing the video of your pet dog to remove the bit where the camera points at the sky because you where texting and forgot about the camera. CinePaint is built to edit the still frames in animation. You could also use it to add titles to individual frames from your video of your dog, giving you hand animated titles.
There is an experimental Windows version of Krita.
Krita is oriented to painting, not image editing, and would be of interest to someone who uses photographs as backgrounds to painted works, perhaps as backgrounds to animation. The following work was created by Enrico Guarnieri using Krita.