As the name Auto Contrast says, this feature automatically calculates the optimal contrast for each image if it is activated. Other than adjusting the contrast with a simple contrast slider, Auto Contrast doesn't cut off details in the dark or bright areas and doesn't produce burned artifacts or a faded look unless you use an Extreme value. Depending on the initial contrast in the image, Auto Contrast will more or less also increase the brightness of the image.
The Auto Contrast Options
The Auto Contrast combo box lets you choose between six options and an Off and Manual setting. Each the six options corresponds to a certain value that is set in the Contrast slider. Here are the descriptions of these options:
|Off||Deactivates Auto Contrast.|
|Mild||Applies the weakest possible contrast correction. Images with a very low contrast will even improve dramatically with this setting. For others you might not see a difference to Off.|
|Normal||Recommended for most cases. It produces a contrast enhancement without cutting off too much details in the dark and bright areas.|
|Strong||Will improve contrast even more in some cases.|
|Intense||If you prefer an intensive contrast in your images, you should use Intense. For some images it may already produce slightly burned or darkened areas.|
|Extreme||Usually not recommended. In most cases it creates white edges in the image that causes an overexposed look. Only very few images will benefit from the Extreme setting.|
|Manual||Lets you adjust contrast manually with the Contrast slider. This works very similar like the Contrast slider you are used from common graphics applications. This feature can produce very unbalanced contrast reduction or increase, so it is normally not recommended to use it.|
If you apply ColorWasher on a screen shot, a graphic or other non-photographic material with only few colors, it is better to switch Auto Contrast to Manual and to use the Contrast slider carefully.
The Boost check box additionally increases the contrast. This feature is especially useful for photos that have a very small deep black areas, but nevertheless a bad contrast. This is usually represented by spikes on the left or right side of the histogram. Without activated Boost increasing Auto Contrast or the Contrast slider may appear to have no or only little effect in such a case.
When using Boost you should use a smaller value for the Contrast slider to avoid blown highlights. You can check your image for blown highlights with the appropriate check box from the Info tab sheet.
The Contrast Slider
The Contrast Level slider is for adjusting the Auto Contrast setting. So if you want to apply a contrast correction that lies between one of the Auto Contrast options, you should use this slider.
If the 'Sat Fix' check box is activated, ColorWasher will process the image while keeping saturation constant when adjusting contrast, exposure, highlights, midtones and shadows. This can improve some photos and avoid oversaturation, but sometimes if the adjustment is too strong, it decreases or increases saturation too much. In such a case it is better to deactivate the Sat Fix check box. An alternative to Sat Fix is the Saturation slider.
The 'Histo Fix' check box removes gaps that can be seen in the histogram view of a corrected image. This means that the number of colors in the image will increase. These gaps are only a sign that a photo was corrected, but otherwise you can forget about them. Please only use 'Histo Fix' if you don't plan to sharpen the photo, because sharpening automatically removes the histogram gaps. However, this feature produces a larger JPG file size.