AA Patterns

How to use the applet

Technical analysis of AA Patterns can be found in the paper "Pixel Patterns from Quantization Artifacts of Forward Affine Mapping", and some of their properties are shown in Eurographics poster "AA Patterns". This applet offers the following:

• The pattern parameter can be entered directly in the alpha field as a decimal number between 1 and 2.
• Alternatively, the user can tune the sub-parameters p, q, t, r, and m. The best way to describe the effect of these sub-parameters is to experiment with them.
• The parameter can also be entered as a continued fraction (cf), where each digit represents an entry. If the entry is more than 9 it must be enclosed in brackets like (10).
• (New) The parameter can be entered as an extended continued fraction where the numerators can be -1, besides the standard numerators of 1 in a standard continued fraction. Simply insert a minus sign to indicate that the subsequent part of the fraction is subtracted instead of being added.
• The pattern can be viewed in source (xy) or target (XY) plane.
• Drag the pattern with the mouse to see different parts of it.
• Shift-drag the applet to turn it into a windowed application, so that you can maximize and see a larger part of the pattern.
• Turn the mouse wheel to scroll the pattern up or down.
• Click on any point in the pattern to bring that point at the center.
• The list on the right shows the frequency of different cluster levels, and the number of points per cluster.
• Click on any entry on the list to switch off/on the corresponding clusters.
• Use the Color Tables list to select a different color table. Beautiful patterns can be obtained by combining the effect of switching off some levels with the suitable selection of color table.
• You can save a snapshot of the displayed pattern, at its displayed size, or at another size of your choice. The center of the displayed pattern is the center of the snapshot, and information for regenerating the pattern are stored as metadata in the saved image.

Known Limitations

1. The value of 't' is currently the main limiting factor, because it determines the size of the coloring table. It is restricted to a maximum of 1000, and the rest of the parameters are restricted accordingly.
2. 'm', independent of 't', is restricted to a maximum of 10, as larger values of m generate too disperse patterns.
3. Considering the above restrictions, any unaccepted decimal or continued fraction entry is highlighted in red.

Please submit any suggestions or bug reports to aapatterns@abdallagafar.com.