With the file extension AHU so-called Adobe HSL files of the image editing software Photoshop are marked. HSL denotes a color space of different color models, in which the color values are set via Hue (hue, values from 0-359)), Saturation (saturation, values from 0-100) and Lightness or Luminance (brightness, values from -100 - 100) ,
The HSL dialog box can be accessed via Hue / Saturation in the menu Picture-> Adjustments, in which also AHU files can be loaded and saved. Ahu files are stored under 'Preferences / Hue and saturation' in the main directory of Adobe Photoshop. This makes it easy to apply your own color settings to an image.
Most often resolving problems with opening AHU files is very simple. Just install an appropriate program that supports such files. All of the listed programs support AHU files, but may vary in offered function and purpose. Some programs may be capable only of viewing contents of AHU files or offer file conversion options, but may not be capable of editing such files.
It is possible that although a compatible program has been installed on user’s system, it is not used by the system to open it. This may happen because no default application was associated with this type of files. To associate AHU files with given application, select "Open with" from drop-down menu (accessed by right-clicking on the file). Then select from the list the program or application you want to be used to open this type of file. If the Adobe Photoshop applications is not on the list, select "Browse" option in order to manually locate the directory where Adobe Photoshop has been installed.
Sometimes problems with opening AHU files may not lie with the application itself, but can arise due to other causes, such as: