Color Reduction with border Detection
Color reduction using edge detection filters is used when you have detailed images. These filters try to detect and highlight the edges of the figures that make up the image. The figures must have sufficient contrast and must not be too small.
Unlike the other filters, edge detection analyzes the contrast of colors according to the chosen directions, either by color, brightness or saturation. In addition, the analyzed areas are reduced according to their minimum parameters, not according to the average color. In some cases edges are detected more accurately than with the other filters, partly because you can choose the directions of image analysis.
There are three filters available:
- Edges by color: the image is analyzed according to its colors.
- Edges by luminance: the image is analyzed according to the brightness of its areas.
- Edges by saturation: the image is analyzed according to the saturation of its areas.
These filters have some parameters:
- Contrast: contrast value between adjacent points, in order to identify the edges to be highlighted. A low contrast identifies more subtle variations, while a high contrast identifies more pronounced variations;
- Edge Above: if this box is checked, the image is analyzed from top to bottom.
- Bottom edge: if this check-box is activated, the image is analyzed from bottom to top.
- Left edge: if this check-box is enabled, the image is analyzed from left to right.
- Right edge: if this check-box is enabled, the image is analyzed from right to left.
The directions in which the image is analyzed can be freely activated or deactivated. If you deactivate all of them, the filter will not detect any edges, so you should leave at least one of them activated.