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Color Reduction with Pen Drawing

Color reduction using the Pen Drawing filter is used when you have detailed images. This filter tries to locate and highlight the figures that make up the image. The figures shall have sufficient contrast and shall not be too small.

The pen drawing detects the edges, regardless of the color of the figures that make up the images. Unlike pencil drawing, black or dark surfaces will be entirely filled with dots. Therefore, this filter is not suitable for night photography.

This filter has some parameters:

- Contrast: Contrast value between adjacent colors to identify edges to highlight. Low contrast detects the subtlest variations, while high contrast detects the most pronounced variations;

- Brightness: The limit brightness value for dark surfaces, i.e. fully filled. Low values will detect and completely fill only the darkest or black surfaces, while higher values will fill increasingly lighter surfaces;

- Surface: The width of adjacent surfaces for edge detection. With small surfaces more detail is detected, less with larger surfaces;

- Distance: the distance between adjacent surfaces. Small values identify colour differences between neighbouring surfaces, while a larger distance between distant surfaces.