Author Topic: Using DBE Symmetries to remove a star reflection  (Read 3001 times)

Offline vpcirc

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Using DBE Symmetries to remove a star reflection
« on: 2013 June 20 08:37:47 »
I have been unable to successfully remove a star reflection gradient using DBE. I think there must be a way using symmetries, but I sure can't figure it out. The stacked fits is located here:

 https://dl.dropboxusercontent.com/u/75904861/light-FILTER_Green-BINNING_1.zip

Offline astroedo

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Re: Using DBE Symmetries to remove a star reflection
« Reply #1 on: 2013 June 23 11:21:27 »
Hi,
i suppose that DBE isn't the right tool for this task.
DBE is intended to model a smooth gradient in images: on your image i see at least three nearly circular, mutually superposed reflections with sharp edges.
I suppose that DBE cannot create such a pattern.

But let's wait for more skilled guys than me  ;)

Ciao

Offline Harry page

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Re: Using DBE Symmetries to remove a star reflection
« Reply #2 on: 2013 June 23 11:38:20 »
Hi

yup I agree DBE will not sort this out  >:D , I am afraid I am not aware of a way to effectively remove them  :surprised:

Harry
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Offline astroedo

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Re: Using DBE Symmetries to remove a star reflection
« Reply #3 on: 2013 June 23 12:17:16 »
Maybe with Pixelmath you can try to create the same pattern (circular features are easy to draw) and then subtract it.

I will try to think about it.  :D

Offline astroedo

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Re: Using DBE Symmetries to remove a star reflection
« Reply #4 on: 2013 June 23 15:03:08 »
Though being quite afar from perfection, I've tried to find a solution, consider it only an idea to develope  :tongue:

The first step was to create a PixelMath expression to draw circles; this is my solution;

xt=xpos();
yt=ypos();
iif(((X-xt)^2+(Y-yt)^2)<R^2,$T+H,$T)

with the following symbols

xt, yt, X=2126, Y=1723, R=670, H=0.0001

X and Y are the center of the circle, R is the radius and H is the value inside the circle: you have to trim this parameters to create the reflections.

I saved the image in JPEG and opened with GIMP to measure reflections position and size.
Using small previews inside and outside reflections to get statistics and evaluate the H parameter.

Using the above expression on a black copy of the image i have created fake reflections and then I have subtracted from the image.
Here the result.

As attachment you can find the zipped icons to reproduce my work.

Open your image and drag the BlackImage icon on it to create the black copy.
Drag the three reflections Icon on the black image and then the SmoothPattern icon.

Finally drag the SubtractPattern Icon on your image, the reflections will be subtracted.

As I said before the result is not perfect, but maybe you can try to trim the parameters to get a better result

Ciao

Offline vpcirc

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Re: Using DBE Symmetries to remove a star reflection
« Reply #5 on: 2013 July 04 09:06:06 »
Thank you very much. I just saw this, and didn't realize someone had figured this out. I'll give it a shot