M33 - What do you mean it's not pink?!!

[swag72]

I knew there was a reason that I don't like galaxies - I can not process the damn things for toffee. Cue M33 ........................

There's a fairly good amount of data here.

60 x 300s Lum 1x1 bin

60 x 300s RGB 2x2 bin

All frames have been calibrated with bias and flats. I was trying out a little experiment regarding RGB that I read about, hence why the amount. Anyway, I digress. This is an LRGB image, with minimal processing really, some stretching and colour boost, but that's about all. I can not get rid of the magenta that I don't see in everyone elses M33's. I've tried the colour selection tool but whatever I do, just seems to not make it a pleasing, nice bright image that I am after.

So can any one help me to get something with some decent colours in it before I chuck in the towel on galaxies altogether!

[Capricorn]

I don't do imaging but is there any chance that the exposures were highlighting or picking up the IR from the dust in and around the galaxy?

Just that it looks pretty good and you seem to have more of what I would say is the galactic dust emissions in the IR then other images that have that filtered/processed out.

It is almost as if you have the "normal" detail with this other aspect present, and if the additional bit is further down the red/IR then I might expect what you have posted.

[Pete Presland]

^{should be quite simple to "tweak " the colour balance}

[swag72]

Cheers Pete - I got that stage, but then there's no colour left at all. The M33's that I like always seem blue in colour. For example, I have linked to a thread where Olly posted an image of M33 in post #12 http://stargazerslounge.com/topic/162996-atik-460-versus-atik-4000-shootout/page__hl__%20460%20%204000. This has less overall data than mine, but does have Ha added.

So, how do I get to this stage with my data? OK, I've not got Ha, but does that make the difference?

Can anyone make suggestions of how I can get closer to this?

Interesting point Capricorn, but I'm sure my pinky version is less right than what it should be!!!

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[ollypenrice]

Sara, your data is great. The colour balance needs a rethink, that's all. You will soon have a classy M33.

I think you use Pixinsight? Put your linear RGB into PI and use DBE and apply Screen Transfer Function's automatic screen stretch, which goes too far but that's ideal. Get DBE to select the background. Be sure that none of the marker points it selects are on or too close to the galaxy. Move them if they are. If any of the background sky markers are refused (turn red) increase the tolerance till they are all accepted. Apply DBE using subtraction.

For me this always gives a good colour calibration though sometimes there are residual green nasties, in which case I apply SCNR green.

This gives me a nice colour balance and I then hot foot it into Photoshop because I don't like images processed in PI, I'm afraid. Well, not often.

Once stretched I look at the colour. For galaxies I sometimes do this;

In Curves go into blue. Pin the curve at the background sky point which I like to be about 23 or 25 at this stage. Put in a second pin below that to stop the bottom of the curve bending. Now slightly lift the blue just above the background sky and slightly dip it near the top, a contrast curve.

Now go into red. Pin the sky as above but do a reversed contrast curve, lowering the mid range and lifting the higher region.

The idea is to get the blues in the spirals to show and the reds to dominate in the brighter core.

If this doesn't work for you just accept PI's colour balance.

I'm certain your data is good.

Olly

PS M33 is not the most colourful galaxy in the universe. Even the colour loving Robert Gendler didn't find as much as he usually does! Viz http://apod.nasa.gov...d/ap030924.html

For once I have more colour than he does, which is a little worrying! http://ollypenrice.s...LRGB-nr2-X3.jpg

[swag72]

A million thank you's to Olly and a little telling off and I've finally got something worth keeping as well as something I will now add some Ha to when the weather allows. So, M33 isn't pink afterall?!!! Woops still a bit of a gradient showing, will look at that when the Ha is added!

[Pete Presland]

that's looking much better sara, well done!