Brightness-dependent controls and enhancements

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clouzot
Posts: 46
Joined: Thu Aug 08, 2019 11:13 am

Brightness-dependent controls and enhancements

#1

Post by clouzot »

This may sound mysterious, but hopefully quite useful!

Sharpcap's Livestack has those simple (yet nice) enhancements that one can use to further improve signal detail (or, on the contrary, blur to lower the noise).

Alas, most of them apply to the whole signal no matter what. For example, sharpening will sharpen whatever signal there is on the stack, be it valuable detail...or background sky noise. I often find myself lowering the kernel size back due to noise, even before ringing artifact start to appear around stars
An exception is the bilinear filter, which by construction has a contrast threshold setting. I routinely use it to clean up the sky background a bit, before applying the sharpening, but on my typical EAA stacks the contrast ("tolerance", in Sharpcap) setting has to be quite low, sometimes even 0.01.

Moreover, the same goes with Color balancing controls, which also apply to the whole stack no matter what. Again, it could be desirable for such a process to apply only to features above a given brightness threshold, yielding highly saturated objects while keeping a neutral sky background, for instance.

It would be nice to have additional controls to further enhance on the fly the livestack:
- finer, or even log-scale setting for the bilinear filter's contrast/tolerance setting. Linear works fine with well contrasted images, but not with your typical deepsky livestack.
- a brightness threshold for the sharpener. Every pixel under that threshold would stay untouched
- separate saturation sliders for low and high brightness features in the stack. This is highly similar to what is found in the Startools processing suite.

Hopefully those additions would have little impact on the UI and performance, while giving greater flexibility to the user. Not knowing how the original DSP was implemented practically speaking, I don't know if it's feasible, or would need much more CPU and memory (applying thresholds may mean mixing the processed image with the unprocessed one, hence twice the RAM), though.
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Re: Brightness-dependent controls and enhancements

#2

Post by admin »

Hi,

thank you for the suggestions - there is certainly merit in them and some would be relatively simple to implement I think. I will add them to the list of possible new features for live stacking..

cheers,

Robin
clouzot
Posts: 46
Joined: Thu Aug 08, 2019 11:13 am

Re: Brightness-dependent controls and enhancements

#3

Post by clouzot »

Thanks Robin 🙏
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