© Steve Hill, 2003

1. Select the channels to be generated using the check-boxes in the channels group.
2. The pre-set buttons LRGB, LCMY and L select common choices of channels.
3. Select the format of image to process. For the MX5, images generated from the AstroArt camera drivers should use YUV for low resolution images and CMYG for hi resolution (interlaced) images. The interlaced option should also be selected for high res images. You may need also to select Y-offset for hi-res images … I need to do this for those generated using the Star2000 self-guide. I do not know if this is a problem for all MX5 hi-res images.
4. Click the "Select" button to bring up a dialog to help choose the correct format for your image. The dialog has a "Guess" button which will try to determine the correct format for you. It has been tested on AstroArt MX7 high resolution images and MX5 high and low resolution images, but has only been tested on Starlight MX5 images. Let me know what setting work for your images and I will try to incorporate detection into the software. Currently the determination is done solely on image size, so cropped images will not detect correctly.
5. Colour processing provides three different methods for generating colour information. The empirical method gives nice clean images with less contrast between the colours. The other two methods produce more colour contrast, but at the cost of "noisier" colour.
6. Colour frames can have a venetian blind filter applied if desired (not usually necessary).
7. Colour frames can optionally be rescaled to a 16-bit range. This is the default in AstroArt 3.0.
8. Luminance frames can optionally be re-scaled to the full 16-bit range using the "Rescale Lum" checkbox, and can have a venetian blind filter applied.
9. The luminance frame can either be generated from adding adjacent pixels, or by averaging a block of four pixels. The latter is best for interlaced images, and I have found that for low resolution it can be preferable since it tends to reduce the noise in the image.
10. Sample 3x3 tells the colour routine to sample colour from a 3 x 3 grid of pixels. This has the effect of a weak low-pass filter and produces cleaner colour images.
11. Fat pixels indicates that each colour pixel should be written to a region of pixels rather than to just a single pixel. Again this has the effect of blurring the colour signals slightly.
12. Low pass filter applies a 3x3 box filter to the final images. Checking "Sample 3x3", "Fat pixels" and "Low Pass Filter" produces the smoothest colour images, but removes the most high frequency information.
13. Use the "Subtract Dark Frame" button to select an image to be subtracted from the incoming image prior to image generation. The check box can be used to disable dark frame subtraction whilst remembering the selected image. The re-bias option adds the minimum of the original frame to the result prior to colour synthesis. Adding or subtracting from an MX colour image causes the colour balance to shift and I have found that for some of my images, a re-bias is necessary to produce the right colours.
14. Use the "Divide by flat" button to select an image to be used to rescale the pixels in the image prior to image generation. The selected image is treated the same way as for the arithmetic divide operation in AstroArt.
15. Images selected for flat field and dark frame operations must have been saved to disk, and will be opened briefly and then closed again. This is normal. They will be reloaded during the colour synthesis.
16. The x-offset and y-offset options are useful if an MX image has been cropped to odd x or y coordinates, or where the software capturing the image is unconventional in its format.
17. To process a single image click the "single" button. If you have multiple images open, you will be requested to choose the image you require -- I have found this to be preferable to using the current image because I always have the wrong one selected and end up with colour images derived from luminance frames etc.
18. To process a set of images, click the "batch" button and select the input files. The resulting processed images will be saved in the same folder as the sources using the same names, but with L_, R_, G_ etc. prepended.
19. NOTE: when the trichromy window is open, you can select R, G, B and L files by pressing CTRL-T. This doesn't work properly in CMY mode -- AstroArt will still select RGB files instead of CMY.

I would like to thank Mike Smith for his invaluable help in explaining the format of interlaced MX images. His own colour synthesis plugin (see www.msb-astroart.com for details) is excellent and features a preview window that can greatly speed up the process.

Mail me on steve_hill at lineone dot net.