colour - startools 1.6 Alpha

[Burly]

Help required please ,So first light with nikon D5300 unmodded ,i chose M31(currently at Zenith )uk , so i could compare to previous data using canon 1000D ,so scope is tecnosky 70Q quadruplet fl 348mm ,idasD2 filter , acquired 1hr 44 min 240 sec exposures ISO 200 (Nikon is iso invariant and 200 seems to be the suggested setting) guided in phd2 Dithered frames 16 pixels (image size 6016x4016) 50 bias frames loaded into Darks tab as im dithering ,that seems to be the way to do it im told, 25 flats ,Eq6 pro belt modded ,deepskydad autofocuser , stacked in DSS ticking box do not white balance , saved as Fits 32 bit interger , chose second option in startools linear etc , - cropped artefacts out -bin 50%- auto dev-wipe-autodev ran through modules decon ,contrast etc leaving colour last before denoise ,now initial feeling is looking good for the life of me i cant get colour out ,so as usual colour module -mask auto stars - shrink x1 grow twice -back to image -sample -mask clear -invert back to image ,just doesn't seem to be any colour popping out though clicking on rgb shows even spread of colour , am i ommiting something ? or is there just not enough data though i thought there would be enough to get a rough idea.
dropboxed fits file for pixel peepers https://www.dropbox.com/s/ftifh1ma1t1ea ... n.FTS?dl=0

regards Dave

[admin]

Hi Dave,

All you need to do, really, is bump up the Saturation.
Depending on the strength of the colour signal (which can be complicated by the use of a filter or a heavy bias signal), the different LRGB combine Method Emulation modes may act differently when making colour apparent.

StarTools_101.png (1.12 MiB) Viewed 5873 times

Does this help?

[Burly]

Thanks ivo I’ve seem to have got there in the end I may be over optimistic with only 2hrs of data though I’m quite pleased with the initial result and certainly less noisy than the 1000D .
https://flic.kr/p/2hC9EV2

[admin]

Good to hear!
Forgot to say/demonstrate that there is a Nikon D5300 colour response setting in the Color module in the latest 1.6 alpha, if you open/import your dataset with the second option (e.g. linear, from OSC/DSLR, not white balanced). Please note that when you choose it, it resets your white balance/bias ratios to what the manufacturer prescribes (so maybe select this option first, and then white balance/sample).

[Burly]

Yes I seen that matrix list I will make a note to try in the order as you say .

Regards Dave

[Burly]

So a few more nights data now at 5hrs 48 min signal looks like it is getting stronger ,though i found rgb cielab luminance retention algorithm gave a better look than the default ,also on the screen shot you can see the smaller stars look orange though once final denoise this was not visible and looked more normal ,how do you think the image is looking now ivo is there anything missing /wrong all data acquired same as first set dithered ,bias as darks flats etc

48992211176_6954b57f66_c.jpg (67.87 KiB) Viewed 5798 times

48991364243_6a0ea4af41_w.jpg (49.32 KiB) Viewed 5798 times

flickr image -https://flic.kr/p/2hDcxKR

Dropbox fits file https://www.dropbox.com/s/41ek2y99kd0wz ... a.FTS?dl=0

[admin]

No major issues I can see Dave!

Just be mindful of your colour balance, as your galaxy comes out entirely yellow.

Consult this info on some techniques to achieve a good colour balance.
In general, you'd be looking for a milk/yellow core, bluer outer rims, red/brown dust lanes and (especially with deeper data like this) purple/pink HII areas dotted around.
In the foreground you will want to see all star temperatures represented from deep red to blue.

E.g. something like this;

StarTools_102.png (1.34 MiB) Viewed 5787 times

[Burly]

Thanks for the advice ivo , I wish I had your skills .

Regards Dave

[admin]

No problem Dave. In the case coming up with visual spectrum colouring, it's not such much about skills, it's more about knowing a little about the object(s) and the physical processes going on.
Colours in outer space can tell you so much about what is going on, what stuff is made of, even about the past and future of an object.

For example, those pink/purple dots in M31 are HII areas are like most the nebulas you are familar with, except in another galaxy. The cool thing is that they have the same colour signature, precisely because they are the same thing!
A relative over-abundance of yellow/red stars in the core (making the core yellowish), means that there has been less star formation there recently (as blue stars burn through their hydrogen much quicker and then explode, leaving the longer lived red, orange and yellow stars), while the outer regions are relatively bluer (with more star formation going on still); it is not coincidence the purple/pink HII areas (correlated with "stellar nurseries") are located there.

With a skewed color balance, you would not be able to see or "prove" these things, so that's why it pays to know what you are looking at, so you can accurately convey these interesting bits to your viewer. At least, that's the documentary approach I prefer to take.