You can also try the Foraxx Palette utility. Even if you dont like the Foraxx image, the foraxx stars that it produces are very good imitation to RGB stars.
I’ve done quite similar processing on many narrowband images where I was, for whatever reason, not able to capture RGB stars, and the stars come out ok. But, capturing RGB stars is always better and it really doesn’t take a lot of effort to capture the RGB stars; they don’t need anywhere near the same amount of capture time that the narrowband images require. That being said, to each his own and if you’re happy with how the image turns out, then that’s all that matters.
100% agree. I personally will continue to shoot RGB stars, but I'm happy to have a joker up my sleeve for situation where I don't have them, out of whatever reasons...
Last week I tried to use narrowband stars from OSC (dual band L-Ultimate) because when I was ready for RGB captures for stars it was cloudy. I tried with a little SCNR, then SPCC with "Average Spiral Galaxy" as white reference. "Narrowband filters mode" and "Optimize for stars" was checked. I liked the outcome.
As you can see in the comparison, they are very close - also thanks to SPCC. In one pic I tested with I had the impression the blue was more intense in the RGB pic, but in general it is a close match.
Hi Sasha I have the Antlia ALP-T SII Hb filter as well as the ALP-T Ha OIII would you suggest 50-50 OIII Hb in the blue channel since Hb is more blue than OIII? I use a pixel math that very accurately extracts all emission lines from my dual narrowband images. I know stars are easy with OSC but I'd like to try this technique in case of emergency
Simply using the scnr tool to remove green from the star image (and the inverted star image) takes care of the greens and purples. Boosting saturation a little bit and you have nice looking NB stars that are close to RGB stars. I've been doing this for years. I'll test the formula to compare but looking at your video.. it appears to yield similar results.
I tried the method you mention a lot and I even covered it in an earlier video, but it never satisfied me. It removed the hues - yes - but in general it only decolorizes the stars and so the result are quite white stars. This formula here is the first I encounter which really brings forward natural star colors which even fit the reality (RGB). And BTW - it is even much more efficient that playing with SCNR and all the other stuff....
I agree James!! The math for SCNR will use the green channel data "IF" the green is less than the mean of the red and blue, otherwise it will use the mean of the red and blue . So using SCNR on SHO data will give you a green channel that is a blend of the SII and OIII that is no higher than the mean of the SII and OIII data, and is a fast way of performing colorized narrowband stars as you say :-) then run SPCC after by treating this as RGB data. I also like this method because SII will typically have less data than Ha data therefore removing the stars should retain more color in areas of high nebulousity. I have thought about doing a video on this but been too busy on another project. I appreciate Sasha's effort but I think this can be done way simplier and people should know about this. The simple pixelmath SCNR math is something like this (note: this does not have luminence control and I do offer pixelmath that does which can be found in any of my AnotherAstroChannel videos in the description): // R: $T[0] // G: iif($T[1]>mean($T[0],$T[2]),mean($T[0],$T[2]),$T[1]) // B: $T[2] However, I would just make it more simple by just using the mean of red and blue anyways, then run SPCC after. I dont know why people make things more complicated than it needs to be by mixing channels so much, especially two red channels of data to help make a green. For me I would keep it simple stupid; pick SII for the red channel, pick OIII for the blue channel and take the mean of the two for the green, then run SPCC and it get you close. The below math or just running SCNR as you mentioned does the job IMHO :-) // R: $T[0] // G: mean($T[0],$T[2]) // B: $T[2] Regards, Bill
@@billblanshan3021 Thanks for watching and commenting. Now you might be 100% correct that your formulas are equal or even better - but you know what they are not? Easier! Because as long as I have to enter a dedicated formula in each channel, I anyway do it with copy/paste, so the lengths of the formula is irrelevant. But I have a great idea what would in fact be MUCH easier: A script from you! 😉How about it? PLEASE!!!! 🙏🏻
If you do not have Sii I assume you are shooting OSC - then please shoot RGB stars which is anyway still by far the best way and really no big effort with an OSC camera
Does not matter in this case - just leave it with the default filters (Sony) as you mix the channels it anyway messes the whole thing up - main thing is you get closer to reality thanks to SPCC.
@@nikaxstrophotography I thought so - but as far as I remember the script requires stretched pics to work, which means you would have to individually stretch the 3 narrowband images to use the script - which is a huge effort and makes it impossible to use afterwards SPCC. Or do you use the script with linear pics?
@@viewintospace Nah I use linear images for this and it works brilliantly, I stretch the stars using Histogram transformation then saturate them slightly in curves transformation and you get proper RGB stars, never failed me either using HOO or SHO. The only tedious part is remving the stars beforehand from all three channels
Thanks for the video, it works pretty well! Note that using SHO stars can lead to loss of many of the more dim stars! How do you choose which filters to use in SPCC, just select an arbitrary set of RGB filters to map the pseudo-SHO stars to? Or is there a specific reason you chose the Antlia VPros?
I chose the Antlia Filters as I used Antlia Narrowband Filters. But yea, that is a bad argument. I would say you can leave the default Sony Filters - as we anyway only average it. As shown in the video it is funny that different stars were brighter and some dimmer as in the RGB - really depends on their emissions. But yes, for a perfect and as realistic as possible star pic there is no way around RGB pics.
While I admire what you are trying to do with this method, the Narrowband stars just do not appear as good as the RGB stars. The red, orange and yellow stars are much more pronounced with RGB stars than the Narrowband which looks mostly yellowish. Blue stars are reasonably true to form. I have tried this method on a number of different targets and had the same outcome. Using BlurXterminator to try to get RGB stars of a similar size as the Narrowband turns them a bit blocky.
I'm on one side surprised by your result as for me it was the opposite - the yellowing and red stats were a very good match, the blue on the other side were much more intense in the RGB images. Did you use SPCC? But at the end we can all agree that nothing tops RGB stars, all that I offer is IMHO the best possible alternative when no RGB stars are available.
@@viewintospace I followed your example and didn't deviate. I wonder if the SPCC process itself might cause some inconsistency. Eg, Capturing stars with 3 nm Antlia NB filters and then using Antlia V broadband in this process must have some impact on the final result.
I tried another target with a different camera and filters and had much the same result. Lots of predominantly orange type stars but very little red stars. But in the end, if you don't look too hard, the result is relatively acceptable. The colours are better.
I stumbled over an official PixInsight RU-vid video where they used ColorSaturation on the bright Magenta stars and it worked surprisingly well. It's quick and produces quite reasonable stars as long as there are no blue stars in the pic.
You can theoretically, if you work with 2 Dualbandfilters like the Askar D1&D2 Filters, but the question is why should you, as it is so easy to shoot RGB stars with an OSC camera.
You can theoretically if you work with 2 Dualbandfilters like the Askar D1&D2 Filters, but the question is why should you, as it is so easy to shoot RGB stars with an OSC camera.
No, but I assume you are shooting color (OSC). For color the effort to shoot RGB stars is even less than for mono, so I would recommend you to stick to shooting RGB stars.
@@SpaceCityAstro Then I would propose you get an Sii filter - not simply because of the stars but in general - that is the whole point of mono shooting....
@@viewintospace no it’s not. Some people shoot LRGB. Others narrowband SHO, or at times HOO depending on artistic taste. Some shoot HRGB. Point is, S filters aren’t mandatory. I have an S filter and sometimes don’t use it, depending on the project.
@@SpaceCityAstro Fully agree with that - sometimes it is not needed as there is no emission. I just thought you did not own one, which sounded very strange to me....