Graphic CCD Imaging Primer
Imaging Made Easy and Fun!
Processing MX5C One-Shot Colour Images

When the raw MX5-C image (see "Raw Image" picture below) appears on your computer monitor, you may be surprised for two reasons:

The grid appearance is due to the presence of the colour filters on the CCD chip. And, yes, the colour is not visible at this point. The image must be converted to colour, at which point the grid will disappear and the colour will become visible.

MaxIm DL/CCD makes the conversion to colour a snap (well, OK, two mouse clicks). The "Convert MX5-C dialog is shown below. As you can see, there are a whole bunch of controls. Looks complicated. Actually it's not! Just click the "Auto" and "OK" buttons (in MaxIm 3, you should also choose which one-shot colour camera you are using, in this case "MX5-C"). Your picture is now visible in glorious colour! (See the "Converted Image" picture below.)

Choose your software:

 
Figure 1
 Convert MX5-C Dialog

In fact, there's one other thing to worry about, but it's pretty easy. Note the check boxes labelled "X Offset" and "Y Offset". Try checking all four combinations of these and see which gives the best colour, as shown in the preview image (use the scrollbars around the preview window to show an interesting part of the image). These offsets are a property of your particular camera and should never change, so you only have to do this the first time you use your camera (MaxIm will remember your settings).

Figure 2
Raw M27 MX5-C image
Raw Image
 Single M27 image converted to colour
Converted Image
 M27 combined colour image
Combined Image

Now that we know how to convert a raw MX5-C image to colour, we can get started. Our example object here is M27. We have 42 30-second images. Here is the procedure:

MaxIm v2.03 & Higher
  1. Convert each of the 42 raw images to colour, using the "Convert MX" dialog discussed above. (If you have a lot of images, see "Using Scripts" for an easier way to do this!)
  2. Save (MaxIm v2 only!) the 42 converted colour images to new files (usually TIFF format). You should always keep your original raw frames unmodified, as a form of data backup. Why? Two reasons: 1) you might screw up, and 2) weeks or months from now you might find a better way to process your images!
  3. Use the MaxIm Process/Combine Files menu option to combine all 42 images into a single image. (You can use the "Auto Star Matching" or the "Manual 1 Star" setting.)
    New for MaxIm version 2.03: use the "Combine" option on the "Process" menu to combine images that you haven't saved to disk yet! This lets you by-pass step #2.
  4. Use the MaxIm Resize feature to "Make Pixels Square". ("New Image Size" should now show as a width of 500 and a height of 373.)
  5. Use the MaxIm Histogram feature to tweak the background and range as you see fit. Experiment!
  6. Save the file to the format of your choice (e.g. TIFF, JPG -- v3 even supports colour FITS!).
MaxIm v1.x - v2.02
  1. Convert each of the 42 raw images to colour, using the "Convert MX" dialog discussed above.
  2. Save the 42 converted colour images to new files (usually TIFF format). You should always keep your original raw frames unmodified, as a form of data backup. Why? Two reasons: 1) you might screw up, and 2) weeks or months from now you might find a better way to process your images!
  3. Use the MaxIm Combine Files feature (on the File menu) to combine all 42 images into a single image. (You can use the "Fully Automatic" setting or the "Manual With Centroid" setting.)
    New for MaxIm version 2.03: use the "Combine" option on the "Process" menu to combine images that you haven't saved to disk yet! This lets you by-pass step #2.
    4. Follow steps 4-6 below at left.

    File Dialog Warning

    Figure 3: File Dialog Warning (see note for step 6).

Note (for step 6) that if the "Size Format" in the Save dialog is not large enough (e.g. 8-bit) to accomodate the largest pixel value in your image, then you should either choose a larger format (e.g. 16 or 32-bit) or use the MaxIm Stretch feature to rescale the image. How will you know if this is the case? A warning will appear at the bottom right of the Save dialog (see figure 3). If you want to avoid this situation altogether, then just make sure there is a check mark in "Auto Stretch" on the "Save" dialog and MaxIm will automatically scale the image for you when necessary. Otherwise, the brightest parts of your image will look black.

Don't be surprised if the individual images look like crap when they are converted to colour (especially in v3 which has a much more aggressive screen stretch than v2!). Once all 42 images have been combined, you will have a beautiful colour image of M27.

You can see the final image in all its glory by clicking here.