partially processed mosaic -red issue?

[pkinchington (Peter (Kanga))]

I have partially processed a SHO (hubble palette) mosaic of eta carina - see attached. My question is what causes the surrounding red colour on the outside edges?

[PKay (Peter)]

Hi Pete

Assume the standard mapping of:
S2 - Red
Ha - Green
O3 - Blue

I suppose that the red areas don't have much Ha or O3

You can try 'proportional' mapping ie:

R = 0.3Ha + 0.7SII

G = 0.2OIII + 0.6Ha + 0.2SII

B = OIII

[pkinchington (Peter (Kanga))]

Originally Posted by PKay

Hi Pete

Assume the standard mapping of:
S2 - Red
Ha - Green
O3 - Blue

I suppose that the red areas don't have much Ha or O3

You can try 'proportional' mapping ie:

R = 0.3Ha + 0.7SII

G = 0.2OIII + 0.6Ha + 0.2SII

B = OIII

Hi Peter - how do I do proportional mapping?

[PKay (Peter)]

Hi Pete

The only way I know is using Pixinsight 'pixelmath'.

But I'm sure there are other ways ie: Using Photoshop

Plenty of info out there, have fun!

[pkinchington (Peter (Kanga))]

Originally Posted by PKay

Hi Pete

The only way I know is using Pixinsight 'pixelmath'.

But I'm sure there are other ways ie: Using Photoshop

Plenty of info out there, have fun!

Thanks Peter I'll have a go at resolving it in photoshop. I have seen a video that uses the free image magic software to do "pixel maths".
Cheers Kanga

[Sunfish (Ray)]

Perhaps there was extra light pollution on the sii filter images or dew or both as there is some very strange red spots. See how it looks in just Ha and Oiii. You can change the relative value of each component in most integration programs.