Registax, Deepskystacker, Rot'n'Stack, IRIS, GRIP

[JEL]

Tools for your sky-watching tool-box

I've tried Registax, Deepskystacker, Rot'n'Stack, IRIS, and now also GRIP.

They're all good, and they're all different.

My own short run-down of their main differences:

Registax

• Stacking: Everything stackable really. Even pictures of rose-beds. It just needs some well-defined key-points to lock on to to align the images (and they can even be dark spots rather than white spots). That's very cool, for example for lunar surface images.
• Problems: I've had a 'double-floats error' show up a few times when trying to stack some large images. My best stacking-results have been when using video-files rather than a lot of single images.
• CPU-threading: seems to be single cpu.
• Prime feature (in my opinion): the ability to use video.
• Missing feature (in my opinion): the ability to use convolution.

Deepskystacker

• Stacking: best with low-noise star-images. Can give full mosaics or auto-crop depending on user-preference, very nice.
• Problems: I've had some weird stuff going on when trying to stack the same large images that gave the 'double-floats error' in registax. DSS say the images register ok (enough stars are found) and seems to do some stacking but ends up stacking nothing. I have searched around to see if others had the same issues and some have had them, but without coming up with a real reason as to why. Either the images are too large for 32 bit to handle or they are too noisy. I'm not sure which it is, but to me it looks like mem-problems. The worst thing about this is that it doesn't indicate any error, so it took a while before I actually discovered that it didn't stack the images I used for testing (which was about 10 3x16-bit tiff files (or 48 bit if you will) of about 80 megabytes each, converted from 3x12 bit (or 36 bit) raw files. Each image was just slightly above 4500x3000 pixels). Trying a test-run with the same images only converted into jpeg gave the same results (IE not working). I had success when I resized them into smaller images though (in pixels), and then the stacking was flawless.
• CPU-threading: is multi-cpu, very nice.
• Prime feature (in my opinion): how easy it is to use.
• Missing feature (in my opinion): the ability to use convolution.

Rot'n'Stack

• Stacking: I have only tried stacking star-images, and that works ok as long as you don't run out of memory (which it did on one occasion for me). Rot'n'Stack had no trouble stacking the large files that gave problems in both registax and DSS. It stacks both ways, giving full mosaics.
• Problems: it ran out of memory on one occasion. The program was last updated in 2005, so a 64bit win7 is not what it's optimized for exactly. During start-up it says the 'mesa.dll' is missing, but if I click the OK button enough times the program starts up anyway. So apparently the runtime engine isn't needed (I'm not really sure what it is but it's called LabWindows/CVI runtime engine, and apparently it's something you can install on windows)
• CPU-threading: seems to be single cpu.
• Prime feature (in my opinion): was the first program that gave me a full mosaic stacking, but I guess the program is out-dated as it is currently so I'm not sure it is needed for anything but a go-to program if all else fails.
• Missing feature (in my opinion): the ability to use convolution.

IRIS

• Stacking: haven't tried stacking anything here. This is not a program for novices.
• Problems: converting fits/tiff's to bmp's always crashes the program for me.
• CPU-threading: seems to be single cpu.
• Prime feature (in my opinion): convolution.
• Missing feature (in my opinion): a manual.

GRIP

• Stacking: I have only tried stacking star-images, and that works really well. GRIP had no trouble stacking the large files that gave problems in both registax and DSS. It only stacks one way though, for lack of a more correct technical term, so you don't get full mosaics with all the images included. You get the anchor-image and then all new images are gradually sliding out of view as the star-positions are aligned. So it doesn't expand the canvas to fit all stacked images. It might just be me that operates the program incorrectly though.
• Problems: haven't found any yet.
• CPU-threading: uses java, so I guess that would make it multi-threaded.
• Prime feature (in my opinion): convolution (i got really good quality from this one, except maybe around the edges which is probably just up to user-settings. I used a fairly blurry video-still of the moon to test it on and the surface-detail was really enhanced a lot while the edge of the moon got a bit over-exaggerated)
• Missing feature (in my opinion): it doesn't make my coffee (yet).

GRIP: http://www.grelf.net.

Deepskystacker: http://deepskystacker.free.fr/english/index.html

Registax: http://www.astronomie.be/registax/

Rot'n'Stack: http://www.gdargaud.net/Hack/RotAndStack.html

IRIS: http://www.astrosurf.com/buil/us/iris/iris.htm