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Bit of coding and my 383 is now an integrating video camera :D


NickK

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It's hot.. so after a bit of solar I spent the afternoon just doing something simple - realtime stacking :)

To shorten the download time, I've made it only use a subframe 1/4 the size of the sensor (in the centre). It then stacks these in realtime and subtracts a constant value each time to stop the image from becoming a whiteout.

Just waiting for darkness but image is the tree across the way with a 35nm Ha filter at f/13 (1340mm fl). Not fps but a few seconds per frame with the 383L.

post-9952-0-27098500-1373825944_thumb.pn

Let me see if it will do fps with the titan :)

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Hi nick..nice hearing from you..not had any reports on solar av or on your use of camera or mods..could you do a short write up on the subject would be great hearing your input...Davy

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Snaping using the Titan.. in this you can see the gradual "whiteout" as I have a subtraction set to 1000.

post-9952-0-19576900-1373827834_thumb.pnpost-9952-0-84461800-1373827831_thumb.pnpost-9952-0-28125800-1373827829_thumb.pnpost-9952-0-91475700-1373827826_thumb.pnpost-9952-0-61102400-1373827824_thumb.pnpost-9952-0-02451400-1373827822_thumb.pn

Basically this is computer based realtime stacking where the frames are stacked/processed in realtime.

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I've now implemented a simple s = (s+i)/2 which gives a nice result - here's the titan just pointing at the fence in the dusk at 670mm fl.

post-9952-0-66470900-1373831638_thumb.pn

it's meant to clear from the clouds at 10.. so I'll see what it will give me in darkness.

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Hi Nick

I think this is the way to go for near real time viewing.

The lack of PAL decoder noise and the opportunity to effectively remove hot pixels with direct USB input has LTD of advantages over analogue video.

Only down side is the need for a lap top.

We've had some excellent posts showing what the Mallicam Extreme can do but these are well into the dedicated Astro CCD price territory.

Clear skies and keep on experimenting!

Paul

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Hi Nick!

Looking good! I have been working away on a similar style application (but targeting the SX Lodestar), but I have been concentrating on the display processing side of things and the image registration. The registration and bad frame rejection has been quite an interesting topic, I have gone through several iterations of algorithms but not perfected one yet (I am after creating something with very little, or no user input with regards to registration and frame rejection). I'll be starting the camera integration after that is complete (I am writing my own user mode USB drivers for the SX camera such that it is workable on Mac without the need to install a whole loads of other software).

I'll start a thread with some WIP screenshots.

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Proof of concept code is almost finished... nothing rocket science.. using 5 second exposures with the 383L without cooling on for maximum noise it will be able to align with translation, rotation and scaling very quickly. I'm not looking to deform the image as live view really doesn't require it - the images you're looking at can be captured and stacked using PI etc at a later stage.

Not really rocket science.. but it will be ideal for it's purpose.

I'll probably enhance this but for now it's about the realtime..

This is one of the test subs I'm using, stretched using PI auto-stretch to show the noise and hot pixels that it happily copes with:

post-9952-0-28642700-1374616005_thumb.pn

The bright object is Saturn.. some hot columns, random hot pixels and a smattering of read noise too - it can align images like this :)

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So it's almost working.. alignment works however I have found one very annoying point with Apple's CIImage library - it outputs 8bit. So you put in a 16 bit image greyscale, apply a few matrix transforms and then it surprises you by spitting out 8 bit RGB.. the impact is that the image you get for stacking is 8bit.

So I'm looking for a nice interpolating library for rotate, scale and translate without needing to install the entire Linux world with it as most libraries such as Magic++ and a few others.

Grr..

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Update.. it's detecting and correcting rotation (image scaled down here)!

Input image:

post-9952-0-46374700-1374697160_thumb.pn

Output image - now with the 16bbp interpolation:

post-9952-0-82364500-1374697169_thumb.pn

This is fully automatic detection and correction :D The translation is simple by comparison :)

It took 8 seconds to complete the rotate, movement analysis and create a corrected image for stacking but that's also including generating a load of processing diagnostic images. It should be a lot faster with optimisation :D

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Day job is product manager/solution architect/product manager/general dogsbody in a completely non-related field.. previously BSc Software Engineering (specialising in networks and parallel/distributed computing), was offered a PhD but decided on the money of consultancy and after 14 years AOSX/ATIK drivers keep me occupied on the train or at home rather than watching the TV.

The static stacking was a day, this was a morning+scattered evening researching the maths/concept and then a solid afternoon-evening of implementing it properly whilst having a relaxing day of vacation :)

I'll need approximately a day of work to finish and optimise..

There are a couple of improvements I want todo:

* interpolate the stacking as a form of drizzle - allowing additional detail to be extracted

* increase the rotational accuracy by 10

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Not finished yet but relaxed this afternoon optimising. It's resolving the same image as above (analysing two 17MB images and generating a new aligned image) in 3 seconds on the CPU. There's a lot more I can do but for now that will do.

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Well the align is working nicely.. downscaled to 800x600 (here the images are simply added together):

post-9952-0-41661300-1375208642_thumb.pn

Native resolution crop:

post-9952-0-62278600-1375208639_thumb.pn

So that's not too bad. I can improve the alignment further with a interpolation output stage rather than a simple pixel-by-pixel stack. Current time is 6 seconds but that can be improved.

Here's a non-aligned stack of the same input frames (downsized to 800x600):

post-9952-0-21710300-1375208993_thumb.pn

Next stage is put it together with a live feed :)

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First light Stacking in the Example Application!

Pentax running at 1340mm (0.88 arc sec/pixel so below the dawes limit) through a window to the fence at the bottom of the garden using the 383L and a 35nm Ha filter to reduce the light.

It's windy outside. Below is an example stacked image where it's not quite got it right on a frame..

post-9952-0-09945400-1375610335_thumb.pn

Just waiting on the youtube upload and you can see it in "realtime" :)

Still needs some optimisation for speed etc but it's there..

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