The Color Halftone filter simulates the result of using an enlarged halftone screen on the layer. The filter divides the image into rectangles and replaces each rectangle with a circle. The circle size is proportional to the brightness of the rectangle.
The Crystalize filter redraws a layer as polygon-shaped clumps of color. You can set the cell size of the crystals.
The Facet filter redraws a layer as blocks of solid color. You can use this filter to make a scanned image look hand-painted or to make a realistic image resemble an abstract painting.
The Mezzotint filter redraws a layer as a random pattern of black-and-white areas in a grayscale image, or fully saturated colors in a color image. You can choose a dot, line, or stroke pattern.