frames from the stack can improve the final finished image. Moving a "cutoff" bar across the graph left to right makes this selection. A blue line that looks like an EKG indicates registration or alignment differences in the images. A horizontal blue line can be moved vertically to set the limit for alignment quality; again, improving the result in the finished image. In other words, we only want the best frames, both in quality and alignment, to end up in our finished image. You will quickly become comfortable with this part of the process as you gain experience with the software. Stacking quality percentage and registration difference percentage is indicated at the bottom of the screen. Normally, the program will default to selecting the best 101 frames to stack. I normally do the stack initially with these 101 frames and see how I like it. I can always come right back and repeat this part of the process if I see I need more frames to get an acceptable finished image.
Once the graph is set to your satisfaction, you can start the stacking process by clicking on the "stack" button. The stacking process begins and a "progress" graph appears, counting down the stacking percentage completed. For 101 frames, this takes about 2 min. When the stacking process is completed, a greatly improved image will appear on the screen. But, we are still not finished. There is one more process called "wavelet processing." Clicking on the "wavelet processing" tab at the top of the screen moves us to this next step.
To me, wavelet processing is the really "magical" part of image processing! This final step magically pulls out, or sharpens, the detail that is hidden in the image. Manipulating slides to adjust the "layer" settings performs this sharpening. You will see the image "sharpen up" as each layer is adjusted so it is easy to visually judge the effectiveness of your processing. This is a valuable feature of the software since it is easy to over process during this phase. If not satisfied with the finished image, you can easily go back and redo the stacking process and the wavelet process. Once you are satisfied with the finished image you can save it by clicking on the "save" button near the bottom right corner of the screen. A box will pop up that will allow you to give the image a filename and designate a folder. Click "save" in this box and the process is complete. For further reference, I recommend you read the magazine article about Registax, written by the creator Cor Berrevoets, which appeared in the April 2004 issue of Sky & Telescope magazine. It is a more detailed discussion of what I have presented here. I understand that Registax version 4 is now available and I have had really good reports about it.
Of course, the webcam and Registax software can be used on the moon and other planets as well. You will soon realize, as thousands of webcam users have already figured out, that the webcam is fantastic! It is much easier and much faster to use than a conventional astronomy CCD camera, and it is super affordable!
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