Optical Spatial Frequency Filtering of Image Sensors ?

The filter is a low-pass filter, it "blurs" out high frequency, and this is required as most digital cameras use a Mosaic filter in front of the sensor to produce color images. The "AA" filter is used to cut out frequency that are between the Mosaic (Usually Bayer pattern) filter and the size of the pixels of the sensor. An Olympus EP2 has ~200 pixels per millimeter, which would be enough for 100LP/mm at the Nyquist rate. It uses a 2x2 Bayer pattern Mosaic filter for color. Color artifacfts occur for resolutions between ~50LP/mm and ~100LP/mm. Cameras that do not use a Mosaic filter typically are not typically equipped with an AA filter. Cameras that do not use an AA filter that use a Mosaic filter for producing color images are subject to having color artifacts in the image.

Buy a Kodak DCS420c and a DCS420m to try this out. Should be cheap on Ebay.