Transform - High Pass

The High Pass filters in the Transform toolbar for images detect rapid changes in pixels using three different analytic matrices. These filters will emphasize linear features such as edges.

 

images\img_filter_highpass_eg00.gif

 

The examples below are based on an example image that is a screen shot of a drawing, converted to a raster image and shown above. The image therefore provides a nice mix of strong horizontal and vertical linear features made up of evenly aligned single pixels as well as pixels arranged in uneven linear patterns.

 

images\img_filter_highpass_eg01.gif

High Pass 1 - Good edge outlining with emphasis on horizontal and vertical changes.

images\img_filter_highpass_eg02.gif

High Pass 2 - Stronger emphasis on edge changes at all angles.

images\img_filter_highpass_eg03.gif

High Pass 3 - Strongest changes at point of intersection of horizontal and vertical lines, else relatively unchanged horizontal and verticals with fuzzing of linear features at other angles.

 

See the Image - Filter topic for a detailed discussion of how matrices are used in filter effects.