This simulates a photo of an inclined straight edge (eg., a carbon-soot-coated razor blade). The degree of edge spread increases linearly away from the best-focus point, located by default at the center. The focus point for the red and blue channels can be moved left or right of center. The edge spread for each channel is the linearly-varying 'edge spread' value plus a constant 'base spread'. 'Slope' controls the slope of the edge, and 'noise' adds random values to each colour. The edge is created in pixel columns with a scaled normal distribution integral (sigmoidal) shape; the edge spread is defined as the x-axis distance between the 10%/90% points of the edge rise.
Use 'right-click, save as' or 'copy' to capture the image below
To analyse the generated image using LoCA Focus Analyser, right-click the image and save it as a PNG file, then go to Focus Analyser and load that file (which will be encoded by your browser as 8 bits per channel-pixel, and the values will be linear by default unless you specified gamma compression above).
For example, below is an analysis by Focus Analyser of an edge generated with the default settings:
