Help with artifact on HDR stack

[Graham Darke]

The image below is an HDR of 8 frames done in Lightroom. I don't care much for large circular splodge of coloured pixels dominating the centre of the image. Shame as the detail below in the solar Corona looks good. These were 8 Canon 600d raws. Anyone know what is causing this feature and how I might get ride of it?

 

Many thanks,

Graham

[wimvb]

Most likely a reflection in your optics. How to best get rid of it depends on which software you use. Try google "halo removal in XX" where XX is your image processing software.

[Graham Darke]

Thank you. 

 

[Midnight_lightning]

There looks like a dust bunny or something on the 3 o'clock position of the ring - perhaps worth taking flats, dark flats if you haven't already?

[whizzbang]

If you can get rid of the reflection it will be a superb image ..... good luck

[wimvb]

11 hours ago, wimvb said:

Most likely a reflection in your optics. How to best get rid of it depends on which software you use. Try google "halo removal in XX" where XX is your image processing software.

My previous comment was based on the small version viewed on my mobile phone. But looking at the large version, I'm no longer convinced that it's as simple as a reflection. The circular area is a lot noisier than the rest of the image. A reflection halo would be brighter, but not so much noisier. What processing steps did you apply? Was a circular mask used in any step during acquisition or processing?

[ollypenrice]

Do you need the HDR aspect?

Olly

[Graham Darke]

Thanks guys. My processing was simply to select the 8 raw files in lightroom and then click " photo merge " then "HDR" and that was it. I had to uncheck the auto align button as it wouldn't even attempt the HDR stack with that enabled. There has been no processing applied other than what I describe here. 

 

Olly, I was hoping to merge the the inner Corona details from the shorter exposures with the longer ones showing the outer Corona in which images the inner bits were blown out. I've tried layers in Photoshop but keep getting ghost images of the moon. I think this is down to the movement of the moon between the exposures. I maybe need to align the layers better.

I've now successfully managed a 3 frame HDR stack which doesn't have the horrible splodge, but it also lacks the underlying smoothness of my image above. It seems that 3 is the limit before the splodge appears. I've tried running multiple stacks using different combinations of subs but whenever more than 3 are selected I get this splodge. I know the data is in there. Just need to figure out teasing it out without inviting the dreaded splodge.

[Graham Darke]

4 hours ago, Midnight_lightning said:

There looks like a dust bunny or something on the 3 o'clock position of the ring - perhaps worth taking flats, dark flats if you haven't already?

Quite right, there is. There's another between 11 and 12 o clock near the edge! Not worried about them too much.

[Graham Darke]

This is the 3 frame one with bunnies removed?

[wimvb]

So, it's a processing artefact, and not the data then. Have yor tried combining the layers with the help of a very smooth mask?

[Stub Mandrel]

try using Registax or Autostakkert rather than HDR.

[Graham Darke]

I will give Autostakkert a go. Never used it to stack single frames before, only video frames. 

Thanks again Wim. I must admit my processing skills are basic to say the least. Some guys at my local club are much more experienced and I'm planning on tapping into their knowledge soon!

[Stub Mandrel]

It works well with a pile of TIFFs, and even tidies up a stack of JPEGS.

[Graham Darke]

Tried Autostakkert and got an " out of memory message".  My Tifs are 102mb each. Might try it again with jpegs. 

 

[Stub Mandrel]

AS3! or AS2!

AS3! works better here.