When taking a photo, it often happens that the image is too light and bright (overexposed) or too dark and dark (underexposed). Correcting this too intense shadows or lights on photographs is very simple thanks to the HDR (High Dynamic Range Imaging) technique which allows you to balance the light and dark areas to obtain a more real photo in terms of brightness.
Cameras generally have this function integrated, on iPhone and Android there are HDR applications while the cheaper cameras take photos at a single level of light exposure, have less contrast and often lose the lightest and darkest colors.
HDR does not work with all types of images, but the best ones to try with are landscapes and low light scenes
You can correct the brightness of a photo using the computer with some free programs that are very simple to use and automatic .
1) The simplest web app to create the HDR effect is Fotor, described in another article.
2) Even easier is the self-correction of Google+ Photos although less powerful.
3) Picturenaut is a program for creating HDR images.
You need to select multiple photos with different brightness and let them process the program which automatically corrects the exposure, alignment and color balance of the image.
Picturenaut has support for RAW images and real-time preview.
Obviously, to create good HDR images it would be necessary to have multiple shots of the same scene, which are aligned.
In this video, there is a tutorial for using Picturenaut.
4) FDRTools is a free program that is more powerful but less simple to use to align images, generate HDRI and other things that I personally cannot explain, but which the more experienced will surely recognize.
5) Essential HDR is a free version program with a limitation, that the created HDR images are resized to 1MB.
With this application you can also correct an HDR photo from even a single image.
6) Luminance HDR is another excellent program recently updated to a new version and completely free.
Light exposures can be corrected both automatically and manually by adjusting color tones.
Another article lists some other free programs to optimize the colors and brightness of photos automatically, easier, to use on the fly, even without any manual configuration.
If you want to work more deeply, you can follow the guide to correct the colors in photos with Photoshop or Gimp .
