Had another go at the AVIs I took the other night. I'd just like to warn all the newbies out there about the dangers of rotating the final image. I purposely had saturn rotated on the laptop screen 90 deg.
I did this because I was getting planet drift on the DEC axis & it was easier to guide the planet back central on the screen along the biggest/widest axis of the toucam, not thinking about the rotation I'd have to do later!
Heres a classic example of image degredation upon rotation of the image.
I've rotated the image in 3 different programs, (as well as registax) & they all gave the same effect for some reason. (image above rotated using pic. publisher) Would I be correct in saying the more images stacked in the final version, the bigger the degredation/elongation of it upon rotation?
I came to that conclusion during the mars madness just recently. 1 out of my many mars images refused to rotate correctly & it just happened to be the image with over 800 frames stacked..
800! Wow, I have only got to stack in the 120 frame range. The image is off screen by then.
if your seeing is ok and you drop the frame rate back to say 5 fps, then by usinig virtual dub or bink and smacker, you can join the movies together, so that you can actually get more images to stack.
the other night with mars, i took 17 movies of mars in 20 mins.
i go one step further, i convert all movies to bmp (with bink and smacker), use bird's ppmcentre to centre the planet and then convert back to a movie to load into registax.
No point in me recording more than 120 frames anyway Davo. Even after zipping they don't fit on the memory stick if they are any larger. I had one of 137 frames, zipped it and it didn't fit into the stick. But we digress from Johns problem.
What size memory stick have you got Ken? That particular problem is actually another one of my problems having no memory stick! Gunna buy a 1 gig or an external hard drive one day!!
Asimov - there ought to be no degradation when you rotate 90 degrees, all that should happen is that the original pixels that make up your image are moved around on the screen to form a new image, there is no processing done that could degrade the result.
Certainly that's how the GIMP does it - it has specific options to rotate 90 degrees that don't alter the image pixels at all. You can rotate 90 degrees one way, then 90 degrees the other way and get back to exactly the image you started with.
Perhaps I led you astray here...when I say degredation, I mean after rotating saturn 90 deg. it has elongated the planet slightly as seen in the pics above. On one other image it actually lost detail after rotation.
Maybe what you are seeing is that the pixels on your monitor aren't quite square...
If you rotate 90 degrees and then rotate 90 again back the other way, do you get back to an image that's identical to your starting point? That's the bst way to check if there is any degradation.
Bird's comment re the pixels not being square seems a good possibility... I've rotational effects too, but again mainly in registax and had just accepted you can't do that sort of thing so I'll have to go back and try again ... I'm starting to build quite a collection of cheap and cheerful digital image processing software that all do one or ther things well - might have to add the Gimp
Regarding the rotation problem: If I rotate 90 deg & back again, no problems. Prevention is better than cure they say. I'll just get myself a better polar alignment & orientate the camera correctly & I won't have to rotate at all.
Would I be correct in saying the more images stacked in the final version, the bigger the degredation/elongation of it upon rotation?
