Histogram Equalization

Some scans only partially use the available color depth and are therefor low in contrast. These images can be enhanced with the Equalization filter, which analyzes the used color shades and stretches the result over the whole available spectrum. The result may not look like perfect scan, but sometimes details can be found, which weren't visible in the original image.


1. display
This display shows the actual distribution in dark grey and the recalculated distribution in bright gray.
 
2. scaling
The display will always use the correct scaling to have ALL values inside. This means the maximum peak will decide about the scaling. If you have one extreme peak the scaling for the other values might not be optimal, with that slider you adjust your scaling ignoring that one peak.
 
3. update
As the it is a hard computing effort necessary to calculate the diagram, it will be done only on request!
 
4. display selector
In
Only the original distribution will be displayed.
Out
Only the resulting distribution will be displayed.
In & Out
Both diagrams will be displayed.
5. White Cut-Off
Upper threshold or white cut off. Larger values will appear as pure white. To update the display please press the button Update.
 
6. Black Cut-Off
Lower threshold or black cut off. Smaller values will appear as pure black. To update the display please press the button Update.
 
This filter doesn't support Line Art and other 1 bit image formats.


See also