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Okay,consider when we decide to mod our DSLR..99% of the time we leave the Low Pass filter in place.
Why?

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Or,could it be that the microlensing on the sensor itself actually requires the SLIGHT blurring effect that the Low Pass filter provides?

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Or,could it be that without it we would see images that look over/too pixelated?

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if so,why?

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But,after modding a cam,I started wondering if by simply removing this filter would provide slightly sharper images..

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AND,if so,I could be the one who applies a slight blur to lessen the strong pixelation from certain images/edges/areas..instead of some piece of glass doing this for me,why cant I handle it,IF there is even an issue in processing?

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By the time you get to post processing, it's too late. The aliasing has already contaminated the image, and blurring will not necessarily help. For example, aliasing may introduce red and blue colors where there is only supposed to be yellow. If you blur it, that may help the edge problem, but the colors will get smeared together.

In real life, when you pour two liters of water into a one liter container, water spills out and makes a mess. But sampling theory is different: when you pour two liters of water into a one liter container, the water folds back on itself and corrupts the entire container! The amount of water is the level detail (spatial frequency), and the volume of the container is the number of megapixels of the sensor. Aliasing is the corruption. Anti-aliasing filters reduce detail down to a level that can fit within the pixel resolution.

Here is what aliasing looks like, using the Carina Nebula Panorama from Hubble as a demonstration (click images below for PNG):





The first image has very little aliasing, whereas the second is riddled with it. To some viewers the difference may be very subtle. It may help to do "A/B" comparison by opening each image in a browser tab and switching back and forth.

Some people prefer aliased images and feel they are "sharper" and more pleasing to the eye. Others dislike aliasing very much. Your personal taste will inform your choice to filter or not.

The demonstration doesn't really show the difference between Bayer CFA aliasing (which can be very nasty) and monochrome aliasing (acceptable to some).

If you do decide that you prefer anti-aliased images, then the next question is how to go about it. One possibility is to depend on imperfections in conditions (seeing), technique (focus), equipment (lens aberration, mount tracking, etc.), or diffraction itself to provide sufficient blur to reduce aliasing. If one or more of those apply to your situation then removing the anti-alias filter may be good solution. For example, the pixels on some sensors are so small that diffraction itself (at f/11) is a sufficient low pass filter. Otherwise, keeping the low pass filter is a good method.

Hope that helps.

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--Daniel

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