The Prefs tab contains some options for defining the behavior of ContrastMaster.
On Start Up
The default On Start Up control is "Previous Settings". This option will load the settings that were previously applied to an image with ContrastMaster. The "Default Settings" option will set all controls back to the default values. The "Logged Settings" option will automatically open the settings that were applied the last time to the same image. It only works if you previously had the Log Settings check box activated and if you use Photoshop or Paint Shop Pro (see below for more information).
Language
The Language combo box switches between localizations of the ContrastMaster dialog. You can only choose between English and German so far. When running ContrastMaster for the first time, it will automatically be set to the language of your Windows installation.
Skin
The Skin combo box features various skin options. Skinning means that the user interface receives a new look. There are different options for imitating the user interface of Lightroom, Photoshop, Photoshop Elements, PaintShop Pro and Affinity Photo. There is also a dark version of Aero (the default UI style of Windows Vista/7), a special PhotoWiz skin style as well as an option to only skin the sliders. You can use a different skin for the plugin, standalone and Lightroom versions. The None option of the Skin combo box recreates the standard controls and deactivates skinning, which requires restarting the plugin or standalone.
Multi-CPU Off (x CPUs)
If you encounter any problems, you can deactivate the support for multiple processors and hyperthreading processors with this check box. The number in brackets displays how many processors were detected by ContrastMaster. For example, for a hyperthreading or dualcore processor you will see "2 CPUs" displayed. If you only have a non-hyperthreading, singlecore processor, this check box will be disabled by default.
Instant Preview
If the Instant Preview check box is activated, the preview is updated while you drag a slider. Additionally the dragging of the split view separation line is done interactively. Instant Preview may work too slowly on computers with an older processor. You can also get the same effect if you hold down the Shift key while dragging a slider.
FX Values
If the FX Values check box is activated, the default values will be higher when pressing the Reset button or using the options of the arrow-down button menu. This concerns the three sliders on the Mix tab sheet as well as the Intensity sliders in the Dynamic Contrast, Adaptive Contrast and Local Contrast mode. This feature is meant for users who mainly use ContrastMaster for dramatic effects and less for photo corrections. The FX Values check box lets them start with higher default values, which saves them some time, because they do not need to crank up the sliders every time they press the Reset button or choose e.g. the "Reset" option on a arrow-down button menu.
Histo Zoom
Activating the Histo Zoom check box in the Prefs tab cuts off peaks when displaying a histogram in the Histo tab sheet. This avoids a flat histogram display where only a few high spikes are visible. That's also how Photoshop displays histograms. This option is activated by default.
Log Settings
With the Log Settings check box activated ContrastMaster automatically saves preset files in the logfiles sub folder of the ContrastMaster folder when you press the OK button to apply a correction to an image. In Photoshop and Paint Shop Pro the presets are named with the file name of the image. In other applications a random number is used, because these applications don't supply the file name of the image to plugins like ContrastMaster. If you apply ContrastMaster a second time to the same image and have Log Settings activated, the previous preset file will be overwritten.
At least with Photoshop and Paint Shop Pro this feature allows you to easily find the settings that you applied to certain images by looking into the logfiles sub folder. For other applications you can only look at the file date and guess which preset file was used for which image.
In connection with the Logged Settings option of the On Start Up combo box (see above), you can use the Log Settings check box to automatically make ContrastMaster start up with the settings that were applied the last time to the same image. So if you need to correct the same image again, you will automatically be presented with the same settings that you used the last time.
In case you don't want to start up ContrastMaster with the logged settings or forgot to activate that option, you can also open the logged settings by right clicking on the Reset button and choosing "Logged Settings" from the context menu.