What software

[rfdesigner]

Hi

I've been using IRIS for many years.. in fact I purchased a very early version when it was still called QMIPS32.

It's been very useful but has its limitations.

Right now I'd like two new things:

32bit per colour processing

Layers a-la photoshop.

Is there anything that can do both of the above without sacraficing all that IRIS can do? .. I really do not want to lose statistical (sigma) stacking or the script facility where you can get a long chain of commands saved in a text file and have it run on a batch basis.

(I might still use IRIS for it's automatic aligning and pre-processing ability anyway).

Derek

[roundycat]

Pardon my asking but if you have 32 bit/channel that makes 96bits overall (RGB). Or roughly 8x10^28 Levels. Given that the web cannot display much more than 7 bit and paper certainly cannot do much better why do you need this massive bit depth?

Dennis

[nightvision]

Not sure about 32 bit but I have heard good things about ImagePlus.

[rfdesigner]

Pardon my asking but if you have 32 bit/channel that makes 96bits overall (RGB). Or roughly 8x10^28 Levels. Given that the web cannot display much more than 7 bit and paper certainly cannot do much better why do you need this massive bit depth?

Dennis

You can't treat it as 2^96, only 3x 2^32... and infact you don't get that. Ususally floating point arithmetic is used and that's only 24 bit mantiassa and 8 bit exponenet, so really it's 3 x 2^24.

I'm running into problems when stacking and then compressing in 16 bit. If for instance you have an image of M42, made up of 100 subs each one short enough not to bleach out the trapesium then the nebula will only be using the bottom few bits. If you try and manipulate that you get noise poking through. I've tried using longer/shorter shots and different stacking including using curves prior to stacking but the fundamental conclusion really is I need greater bit depth in processing... primarily for stacking.

How many images of M42 have you seen where the tapesium isn't bleached but you also get the nebula in full glory?.. My guess is only ones taken through narrow band filters and then combined.

I'd like to see what can be done with essentially unlimited bit depth, which is what 32bits achieve.

Derek

[roundycat]

Here is a not very good effort to demonstrate the principle of layer masking a bright area into a dim one. All done in 16bit. Astrophotography

There is adequate depth of information to do all that you want to do. I had this discussion with Eddie Trimarchi and others on one of the Yahoo groups years ago and we agreed to differ.

Their attitude seemed to be "I can use 32 bit if I want to". Mine was "you can use 32bit but don't try to tell me that there is a significant, visible advantage when the final display is in 7bit".

There is a purist argument about having as much headroom in the processing as possible hence the talk of using 32bit, it obviously reduces quantisation errors. Just don't kid yourself that you will ever see the difference on a monitor or on paper.

Dennis