The Load settings select box lets you choose one of the predefined settings for this tab. You can also save your current settings for future use.

The Contrast  moves pixels  from the center (>0) or to the center(<0) of the dynamic range.

Original image	Contrast (+50) applied	The histogram for the original (upper) and the resulting (lower) images.

The S-curve on the histogram means that the central part is stretched and the corners (highlights and shadows) are compressed.
Please note that unlike contrast control behavior in other programs, no information is lost by pushing pixel values beyond the dynamic range (0-255).

The Gamma "stretches" the histogram in the shadows which makes dark pixels brighter, and compresses the highlights. Or vice versa.

Original image	Gamma (+20) applied	The histogram for the original (upper) and the resulting (lower) images

The curve on the histogram shows that the left (dark) part is stretched to the right  and the highlights are compressed.
Please note that no information is lost by pushing pixel values beyond the dynamic range (0-255).

The Exposure makes all pixels brighter or darker by the same degree. The effect is similar to changing the ISO, exposure time or aperture on your camera.

The histogram for the original (upper) and the resulting (lower) images.

The Auto contrast check box enhances the image by optimizing the dynamic range. It is done by "stretching" the histogram so that no "unused" space is left near the edges.

The Black point  slider defines a color in the original image that should appear as black on the resulting image.

The White point slider defines the color in the original image that should appear as white on the resulting image.

These sliders define the "left" (black point) and the "right" (white point) limits for original histogram (note red lines on the image below).

Original image	Autocontrast applied	The histogram for the original (upper) and the resulting (lower) images.

As you see, Autocontrast function "crops" the histogram: it takes only a part of the dynamic range (e.g. 20-230) and stretches it to the full dynamic range (0-255).

The Local Contrast acts similarly to Auto contrast, but it is more subtle. It is very useful when there are only highlights (i.e. sky), shadows (i.e. earth) and almost without midtones. In this case you can see two big hills on the histogram . Applying local contrast will compress midtones and pull more details from the shadows and the highlights by stretching them.

Original image	Local contrast applied	The histogram for the original (upper) and the resulting (lower) images.

The Highlights  acts like Brightness or Gamma but only for light pixels. Use this control if you want to change the brightness of highlights but keep midtones and shadows unchanged.

The Shadows  acts like Brightness or Gamma but only for dark pixels. Use this control if you want to change the brightness of shadows but keep midtones and highlights unchanged.

Original image	Shadows control applied	The histogram for the original (upper) and the resulting (lower) images.

On the example above the brightness of the cliff has changed but the sky stayed the same. This control does not produce halo effects.

The Haze compensation can be used to minimize the haze effect. These sliders add some contrast and saturation mostly to midtones. The haze usually adds some blue color to the image and the program tries to compensate this too.  Please tune a white balance with the Color tab if you are using this function.

You can also apply a similar effect locally by using the Change brightness brush with Anti-Haze effect on.

Original image	Resulting image

The Haze/Gradient slider lets you apply a haze compensation only to a part of the image. For example,  value of +30 means that only the top 1/3 of the image will be affected. This feature is very effective for enhancing the cloudy sky.

Original image	Resulting image

The Exposure warnings option shows overexposed and underexposed pixels.Too bright pixels are marked with red, too dark pixels - with blue.  This option is also present with the Brightness tab.

Original image	Exposure warnings enabled

The Brightness equalizer shows the final curve which is used by the program to modify pixel luminosity. The curve is formed by the controls above and can be additionally modified by the user. To modify the curve simply click on the equalizer or drag the curve. To reset your changes, make a right click on the equalizer.

The curve can be shown as "curve" or "equalizer". You can change this option in the preferences. The "Curve" mode is an analogy of the curves in Adobe PhotoShop, it shows the function y=f(x), where x (horizontal coordinate) - luminosity of the original pixel, y (vertical coordinate)  - luminosity of the resulting pixel. If no modification is applied y = x and curve looks like a straight line.

In the "Equalizer" mode the curve shows by what value the luminosity of the pixel will be changed. If the curve is a horizontal line in the middle, it means that no changes will be applied.

"Equalizer" mode	PS compatible "Curve" mode

Brightness equalizer also shows two histograms on the background. The upper histogram shows pixel distribution of the original image, the lower - distribution of the resulting image.

The Zone size slider defines if the effect of other sliders is based on the brightness of each individual pixel (slider set to 0) or it is based on some average brightness. The slider defines the size of the zone to use for such averaging. Please note, that this slider itself does not affect the image but it changes the effect of other sliders such as Gamma or Shadows.

Tip: Use high values if you have only several large dark and light areas (e.g. bright sky and dark field). Use low values, if you have many small high-contrast areas (e.g. leaves on the bright sky). Set the slider to zero, if you want the changes to be applied to each pixel individually.

The Autodetect slider allows the program to analyze the image and to change some controls accordingly. The slider allows you to define how strong the program may modify the image.

If you apply Auto contrast the program will "stretch" the "hill" to fill the entire dynamic range and the detail level will rise.
In general, you can increase the detail level by stretching the "hills" (that is to say, the concentration of pixels with similar brightness) and compressing the flat areas of the histogram. That is exactly how  Local Contrast works.

Please remember that increasing the level of details also makes noise more noticeable.