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Old 25-04-2016, 10:31 AM
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Shiraz (Ray)
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Shiraz is offline
Join Date: Apr 2010
Location: ardrossan south australia
Posts: 4,787
Comparison of colour exposure strategies:

There are many ways to expose colour images using filters and a mono camera. Some methods seem to be significantly more efficient than others (time wise). The attached spreadsheet shows the results of a very simplistic analysis based on scaling to get to the same SNR as the first strategy presented. Time in hours has been presented for my system for a bright target, but the main point is the comparison of the different approaches, not the absolute time.

The four possibilities summarised in the attached spreadsheet are:
1. Lum + RGB full res where the RGB subs are not long enough to be sky limited ie they cannot be added to the luminance stack, but may be adjusted for the desired dynamic range.
2. As above but with RGB subs that are also sky limited and that are added to the luminance stack. This approach does not allow the RGB subs to be deliberately shorter to increase the colour dynamic range.
3. Lum + 2x2binned RGB where the RGB data only requires as long, but has lower resolution, so cannot be added to the luminance question is, does this lower res introduce any complications?
4. RGB with subs long enough to be sky limited, but with no luminance. This cannot be equivalent to 1. above, so have chosen the time required to get to the same luminance SNR, but with higher quality colour results. It can take a long time to get results, but maybe they are worth the wait?
5. added on Rick's suggestion in later post - RGB 1x1 subs long enough to add to luminance, then software bin RGB to generate the colour data.

Based on this very simple comparison, there may be significant gains to be made in time required for an image, simply by choosing an appropriate strategy. I have been using strategy 3. above with reasonable results and it is definitely quicker to get to a given result than my previous use of strategy 1. Would be grateful for any feedback/opinion/corrections a simplistic analysis like this is only just a starting point.
Regards Ray
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Last edited by Shiraz; 26-04-2016 at 11:42 AM.
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