m36

[ollypenrice]

22 minutes ago, alacant said:

Hi

That's almost certainly why your histogram is clipped. I thought it maybe misleading for beginners. Anyway, it doesn't matter; any beginner would have lost it way before then!

Our question was about star colour, not background but as a result of the thread we've been able to fix both:)

Thanks again. I think we've solved all the issues now.

 

I don't think so but let's find out. Here's an image of mine.

And here's a screen grab of that image opened in Ps with the histogram displayed.

As you can see, the use of a screen grab has not induced clipping though the black point has been affected to a tiny extent, perhaps. So I think the use of a screen grab gave a safe approximation of the original.

Olly

Edit. For completeness here's the original image in Ps with its histo displayed.

 

Edited February 1, 2020 by ollypenrice

[alacant]

30 minutes ago, ollypenrice said:

a screen grab of that image opened in Ps

Yes, thanks. But that's not a screen shot of a jpg posted to internet.

It really doesn't matter! Our images are slowly improving we think. We've taken on board all your comments and have learned a lot from them.

FWIW, the corrected image is here. Not perfect, but heading in the right direction. Probably!

Thanks again.

 

Edited February 1, 2020 by alacant

[ollypenrice]

3 minutes ago, alacant said:

Yes, thanks. But that's not a screen shot of a jpg posted to internet.

It really doesn't matter! Our images are slowly improving we think. We've taken on board all your comments and have learned a lot from them.

Thanks again.

 

The process I followed with my own image was in every way identical to that I followed with yours. I posted the image on here, screen grabbed it, checked the histogram in Ps, screen grabbed that and posted it below the original. No clipping was induced by this process.

Olly

Edited February 1, 2020 by ollypenrice

[Martin Meredith]

Very interesting thread! To follow on from Vlaivs earlier comment about colour temperature, I've been recently looking at the colour data in GAIA data release 2 in order to compare against some of my images, and coincidentally downloaded data in the M36 region yesterday. Here's a plot with colour indices mapped to temperature and then to RGB values (using this technique: https://stackoverflow.com/a/45497817). I've enlarged the stars a little so the colours show up better. The image needs to be rotated 90 degree clockwise to line up with Alacant's image. This is down to GAIA mag 17 although the data is available down to around mag 21-22 (but the colour data is not reliable I believe past mag 19).

Martin

Edited February 1, 2020 by Martin Meredith
(correct spelling of Vlaiv's name!)