Input Level box
The Input Level box displays the value of Shadow Threshold, Midtone and Highlight Threshold respectively. You can also input each value here directly.
Output Level box
The Output Level box is used to expand the output level of the image Colour. You can either drag the triangles below the bar or enter the value directly to adjust.
If the Input Level is set as 20 to 230, then 210 (230 minus 20) Colour levels can be represented in the image. If you set the Output Level as 10 to 250, then the original 210 levels of Colour can be “expanded” to 240 levels (250 minus 10), which can enrich the Colour and display more details in the image.
You can also click on the Auto button in the dialog box to adjust the histogram properties automatically. When you have finished with adjustments, you can click OK to apply, or click Reset to restore the default settings. To abort and exit the dialog box, click Cancel.
