I have made a few notes here regarding my basic techniques for image processing with my previous MX7C CCD camera and also the webcamera. I will include my techniques for SXV-H9 processing when I get time.
The following section include some techniques I've learned using Astroart 4.0 to process and enhance my images.
normally use Star 2000 while guiding with my LX200 and, although I previously used Hires-self
guide mode, I've now switched to Hires Progressive as this will allow me to half
my exposure time compared to the former method by taking full advantage of the
chip sensitivity. I normally try to guide on stars in the mag
6-11 range and usually this is very possible as I can purposely misalign my
guidescope to select a suitable one. Guideframes can be as long as 5 sec as my
scope is well polar aligned and doesn't need much guiding adjustment. I
always use 2X2B&W binning for the guide frames.
following is the process that I use for processing images from the MX7C camera.
the normal routine to acquire
all light frames, darks and flats ( I tend not to use Darks as the SX cameras
have very low noise)
a flat image in Astroart and run Mike’s MX Colour Synthesis Plug-in. An initial
colour image will appear.
Select the "Synthesis" tab, leave the "Lum Stretch" set to Linear, turn the "Luminance HPF" to off and set the "Lum Histogram" to 0. Select the "Colour Adjust" tab and press the "White Balance" button. This will white balance the image. Select the "Batch FITS" tab and then select the list of flat images taken. Select "Open" and the program will batch convert the flat images to synthesized RGB and L. Use "Preprocessing" to average only the L_Flat frames into a master flat and save this to disc.
Use this master flat file and the darks to calibrate the raw light frames.
Now open a calibrated raw image and use Mike's Colour Plug-in, as before, to create a set of L,R,G & B frames from the raw images.
Open an L frame and select a star (
or two ) for stacking alignment, close the frame, go to the Tools/Preprocessing menu,
select the L frames to stack and drag them to the "Images" window.
Go to the "Options" tab and select "add" or
"average", deselect the "confirm image" box, select the "Auto
Alignment" box and either "one star" or "two
star". Select "OK”
and the images will be stacked at the bottom of the screen. When
completed, a minimized "noname" image will be left. This is the
stacked image and should be named and saved.
Set the "Edit > data format" to "floating point"and resize the image to square the pixels. The squared image size for the MX7C is 779 x 580.
The same process should be used for the R,G and B frames.
I have found the Smart Star Bloat Filter Plug-in to be an excellent tool for cleaning up the Luminance frame and tightening the stellar images. Therefore I tend to use it as this stage with an agressiveness of 3 or 4 depending on the image. The resulting L frame will then be ready for final processing.
Processing the Image
The background values have to be equalised otherwise the colours will not appear correctly because the colour balance will be upset. Open a colour frame and use the "Arithmetic > Add offset" function to do this. Subtract from the frame a value that will leave the background at, say, 500adu. In other words, if the background is 2500, subtract 2000, etc. Next, increase the white point, using linear scaling, to a value that shows the object fairly well and set the background visualization at 50. Repeat this with the other two colour frames. Now each of the three colour frames has a background of 500 and the visualization is the same with each frame.
Select the "Colour" button on AstroArt menu and select "Trichromy". Use the defaults and select "OK". The resulting image is a synthesized RGB image. The sky background should be dark grey or nearly black but, if not, use the colour sliders to vary the individual colours until it appears so.
To make the LRGB image, again select the "Colour" tab on the Astroart menu and select "LRGB synthesis". A prompt will ask for the L frame and, once this is entered, the LRGB image will be created. The colours can be adjusted using the "Colour" then "Saturation" tab and the sliders.
At this point the image will hopefully be pleasing but can be further adjusted using Photoshop or some similar application.
This is a short summary of the process I generally use. Depending on the image quality etc., there may be a need to use DDP filtering etc during the image processing but, as this varies greatly from image to image, I have not covered it here.
This is a new venture for me so I have not yet had the experience to give my own tried and tested methods of image acquisition and processing. I would, however, recommend referring to the following sites for some very useful ideas.