The result will be three Fits files, one for each colour channel. However, AstroVideo will have combined the channels automatically and the result can be saved as a BMP.
I shall conduct this tutorial indoors with the camera pointing at a recognisable object. The purpose of the tutorial is to take you through the procedures rather than concentrating on the results. I suggest that you follow the tutorial indoors before you use AstroVideo to capture data on the Moon or the planets.
Connect the driver.
Click on Video, make adjustments as required, but also set the compression to uncompressed frames if you have this option.
You should have an image in the left hand preview frame (Plate 1).
Click on the setup icon and make sure that Colour images is checked and Auto save images is unchecked.
Select the folder into which you want the results to go. I have chosen a folder called 'Demo' which is on the Desktop (Plate 2). Note: this folder MUST exist.
Click on Capture and AVI (Plate 3)
Give the AVI that is about to be captured, a name. I have called it 'saturn'
Click on Save (Plate 4)
Set an appropriate duration for the AVI. I have used the default of 10s.
Click on OK (Plate 5)
As the AVI is being captured, the number of seconds left is displayed in the top bar of the application window (Plate 6)
You have now captured an AVI called 'saturn.avi'
It is time to find the sharpest images in the AVI.
Click on Tools, Process AVI file, Find sharpest (Plate 7)
Select the AVI to use. In our case, we only have the file 'saturn.avi'
Click on Open (Plate 8)
You are then presented with a box that shows the First and Last Frames to be processed. You can change these, but I shall use the defaults. My AVI shows the first frame number as 0 and the last frame number as 136.
Click OK (Frame 9)
You are now given the option to select the number of sharpest frames to save from the AVI as Fits images. I shall use the default of 10. However, if I was imaging the Moon, I might select just 1 and save just the sharpest image (although, for peace of mind, I might increase this to say, 5 just to do a visual inspection of the 5 sharpest frames). In a real imaging session, hopefully, the sharpest frame will represent the fleeting moment of best seeing that was captured by your AVI.
Click on OK (Frame 10)
You then have to give a filename for the sharpest files to be saved. I have called them 'rings'
Click on Save (Plate 11)
An image will now appear in the results window. (Plate 12)
If I was imaging the Moon, this is where I would stop. However, if I was imaging the planets, then I would wish to align and sum the sharpest group of frames into a single image. This would increase the signal to noise ratio and reinforce the real structure hinted at in an individual frame.
Let us now register (align) and sum our sharpest frames into a single image. We shall use the Autosum function using a large correlation area:
Click on Tools, Combine images, Options (Plate 13)
Set up the parameters as shown in Plate 14.
Click on OK
Plate 14
Click on Tools, Combine images, Auto sum (Plate 15)
You will be asked to select colour files to combine automatically. Just select the red channel for each filename (AstroVideo knows to expect a green and a blue channel file as well, as long as Colour images is checked in the initial setup)
Click Open (Plate 16)
Place the red box over an area of the image with lots of structure and then Left Click (Plate 17)
This red box is the alignment region within which the frame registration is carried out.
When the autosummation of the frames is complete, you will be asked to give a filename to the resulting image. AstroVideo reminds you in the top bar of the Save image box, how many frames have been summed. I have called the file 'sum10rings'. Click Save (Plate 18)
This colour image will have been saved as the three colour channels Fits files 'sum10rings(blu).fit', 'sum10rings(grn).fit' and sum10rings(red).fit (Plate 19)
The final image in the right hand pane can also be saved as a BMP (Plate 20)
As always with Video Integration techniques, think big. Capture as large an AVI file as is reasonable as this will statistically give you the best chance of capturing some good frames to integrate (sum) later.
Practice this tutorial indoors before you capture astronomical images. Good luck
Copyright © S.J. Wainwright 2002