The tone scale (contrast) of an image represents the distribution of lightness values. It is a combination of Brightness and Contrast.
The brightness of an image relates to the overall sensation you get when it is viewed. If most of the tones are large, the image appears to be bright. If most of the tones are small, the image appears to be dark. Adjusting the brightness therefore tends to shift the average tone value either up (to make the image brighter) or down (to make it darker).
The contrast of an image relates to the range that the tones occupy. If most of the tones in an image are similar to each other, then the image has a low contrast and appears "flat." If the tones are spread widely across the scale, then its contrast is high. Therefore a contrast adjustment either spreads the tones out (increasing the contrast) or compresses them together (lowering the contrast).
Paint Shop Pro has several commands that are useful for adjusting the brightness and contrast of an image. Go to the Adjust > Brightness and Contrast submenu for a list of available commands.
The Automatic Contrast Enhancement command is useful for improving the tone distribution of your image. It automatically adapts its behavior to the tone content of each image. Therefore, it will be most effective when used without any selections, because then the entire range of tones will be available for analysis.
Important: This command works on 16 million color and greyscale images only. To increase the color depth of an image, see Increasing the Color Depth of an Image.
To use this command:
Choose Adjust > Automatic Contrast Enhancement.
In the preview window in the upper left portion of the dialog, center an important part of the image. Pan the image by dragging the cursor in the preview window. Zoom in or out as necessary.
Set the Bias (which is the overall brightness) to your preferred target brightness. The command will automatically adjust the brightness to match this target.
Set the Appearance (which is the overall contrast) to your preferred target contrast. The command will automatically adjust the contrast to match this target.
Set the Strength of the correction to either Normal or Mild depending on your preference.
Click OK to apply the correction.
Basic Steps in Improving Photographs
How to Approach Color, Contrast, and Saturation Adjustments
Common Problems and How to Solve Them
Removing Image Defects and Noise