Re-processing my image of Heart Nebula 18/11/2019 using Roger Samworth’s gradient removal technique in GIMP 22/11/2019

This is my own attempt to remove the background gradient from my Heart Nebula image using Roger’s processing technique.

Andy

Results of stacking in Nebulosity (image used for process below):

Cropping the above image:

Applying masks – as per Roger’s technique:

The above image is close to final image, but I have added further layer with masks:

(i) General mask through most of central region but leaving another blurred background as per Roger’s technique just at edges where green slipped through. Central areas masked with 100% opacity 500 sized eraser.

(ii) Towards edge used 40% opacity initially with large 50 sized eraser.

(iii) Very close to edge used 40% opacity size 10 erazer to bring out missing stars without bringing back too much green background.

(iv) Finally, apply slight crop to remove very small part of edge around image where I haven’t been too successful!

Final image:

Roger Samworth, who developed this technique, produced his own further version of my picture above which he feels brings out more of the nebulosity:


I think the above image has too much blue glow so I re-processed my image again by creating 2nd layer, tweaking red curve on top layer and using eraser around edge as well on this layer to stop the tweaked red from increasing red level of surrounding stars – my new version emphasising red below:

2 Responses

  1. Some comments here.

    Firstly, my eyesight is somewhat challenged in the reds, so who am I to comment about red regions!

    Secondly, I find that with this sort of DSO, what you see can be significantly dependent on what screen you view it on, and on the angle you view the screen. I normally use a desktop monitor, but the view on the PC’s own screen, a tablet or a phone are all quite different.

    Having said all that, to me, I can see the red boundary of the left and right “ventricles” on the image I processed, for example, whereas I can’t on Andy’s.

    I would be interested to hear what other people can see.

    Again if you seek the “truth” by looking up images of this sort of DSO on the web you get an enormous variety of colours! Maybe we should go back to the good old days of black and white!

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