While a "one-shot" color camera with built-in Bayer matrix is handy for shooting a quick color picture, imaging with a monochrome camera provides the best quality, sensitivity, and resolution.
A filter wheel is used to create color images using a monochrome CCD camera. The simplest method is to use three filters, one for Red, Green and Blue. Once the three images are captured, calibrated, and aligned and stacked, it is very simple to create the color composite image. That is because images are normally stored as three red, green, and blue planes. Your computer monitor simply displays the three colors directly; the human eye interprets different combinations of those three colors as a full gamut of different colors. It works because the retina in the human eye itself is based on red, green, and blue light-sensitive cells.
There are other ways to generate color images; the most popular is the LRGB technique, described in the following sections.
In LRGB imaging, a Luminance (L) frame is added to the standard RGB mix. The Luminance fully or partially replaces the luminance information from the filtered images. Often the Luminance image is taken with a longer exposure. The RGB images are sometimes binned to allow shorter exposures with higher sensitivity.
Since the human eye has lower resolution in color than in luminance, the difference between binned and non-binned RGB components in the final image is generally not discernable.
The big advantage to LRGB is exposure time. You can spend most of the imaging time capturing high-resolution, high-sensitivity Luminance frames. This can greatly reduce the time required to achieve a given signal-to-noise ratio for an object.
There are some disadvantages to LRGB. If you are imaging low in the sky, atmospheric dispersion will degrade the Luminance frame more than the RGB frames. With simple RGB you can just tweak the alignment of the three frames to reduce the effects of dispersion. Also there may be a modest shift in the color balance of the final image. Generally speaking, though, the advantages of LRGB far outweigh the disadvantages.
MaxIm DL supports automated LRGB imaging via Autosave Sequences. You can configure different exposure and binning settings for the various filters. Once you have acquired the raw frames, the Stack command can automatically calibrate, align, stack, rescale the binned exposures, and create the color composite. This level of automation makes it very easy to create LRGB images.
An alternative technique that has been promoted in recent years is the use of Cyan, Yellow, and Magenta filters. The advantages quoted include wider bandwidth resulting in more light and therefore higher signal-to-noise ratio.
Unfortunately there are several problems with CMY filters. To build a usable RGB image from the CMY set, the images have to be added and subtracted from each other. Since the noise in the three channels is uncorrelated, the resulting noise in each R, G, and B channel is larger than that in the CMY channels. As a result, the improvement in SNR is extremely tiny, and is not worth the extra effort required.
CMY filters have additional complications. Attaining an accurate color balance with a subtractive system in the presence of the varying sensitivity of the camera across the band is a difficult proposition. Also atmospheric dispersion effects will be worse with the wider filters. As a result, although MaxIm DL supports CMY imaging, it is not recommended in practice.