Using Heal to process stars and background independently
Posted: Thu Dec 06, 2012 10:17 pm
Let's say we have this image here;
Let's create a star mask that Heal can use to heal out the stars; (Mask, Auto, Stars, set 'Exclude Color' to 'Red' so that it won't select much of the nebula);
Now run the Heal module, but make sure you set 'New darker than old' to 'Yes'. What this does is guarantee that replacement pixels for the stars are always darker than the stars themselves;
'Keep' the result and save the healed image for future reference. Now reset the mask (Clear, Invert) and launch the Layer module.
In the Layer module, click Undo->Bg. This will set the background to what's in the undo buffer (which is the original image).
Now set Layer Mode to 'Subtract' and voilà! We have perfectly extracted the stars;
Save the star field - we'll need it later to layer it back in.
Click 'Undo' to restore the background-only image.
Now let's have some fun with the background!
For example, let's do some wavelet sharpening of the larger scale details;
There's plenty more we could do (Life, Wavlet Denoise, HDR, etc.) but for the purpose of this demo this is enough.
Once we're happy with our new background, all we need to do now is layer the stars back in.
Launch the Layer module, click Open, locate and load the stars-only image.
All we need to do now is simply 'Add' the stars back to the background. And Bob's our (proverbial) uncle!
Note that stars may be slightly blow out in places where nebula+starlight exceeds unity (= pure white). This should be fairly minimal, but if that is a concern to you, set 'Cap Mode' to 'Normalize'.
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- Miquel_Heart_PreLife_Post2_crop.jpg (58.82 KiB) Viewed 41412 times
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- img_129.png (407.03 KiB) Viewed 41412 times
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- img_130.png (331.95 KiB) Viewed 41412 times
In the Layer module, click Undo->Bg. This will set the background to what's in the undo buffer (which is the original image).
Now set Layer Mode to 'Subtract' and voilà! We have perfectly extracted the stars;
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- img_131.png (682.37 KiB) Viewed 41412 times
Click 'Undo' to restore the background-only image.
Now let's have some fun with the background!
For example, let's do some wavelet sharpening of the larger scale details;
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- img_132.png (350.42 KiB) Viewed 41412 times
Once we're happy with our new background, all we need to do now is layer the stars back in.
Launch the Layer module, click Open, locate and load the stars-only image.
All we need to do now is simply 'Add' the stars back to the background. And Bob's our (proverbial) uncle!
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- img_133.png (706.96 KiB) Viewed 41412 times
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- Miquel_Heart_PreLife_Post2_crop_bg_new.jpg (60.56 KiB) Viewed 41412 times
