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Levels and Curves - What next


johnb
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Hi

Well I have finally mastered (well just about) levels and curves so whats next on the learning curve

I see references to Unsharp Masks and Gaussian blur etc etc but im not really sure after levels and curves whats the next logical step ? also it would be good to understand what a Gaussian blur does in addition to how etc

General Pointers appreciated.

Regards

John B

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Brightness and Contrast are the next main ones for me.

I play with exposure, colour balance (if too much of one filter), saturation and vibrance normally.

Add on them layers for stars and backgrounds, and of course don't forget to feather everything you do.

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After curves to stretch... curves to increase contrast across the board, and localised... tweak colour balance and saturation, gently gently, Noels Tools for deep space noise reduction, sometimes a gentle waft with something like noise ninja... perhaps a high pass sharpen if needed.

I went through martinb's tutorials on here, and have added things from Steve's book and as I've found out things online.

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Don't be tempted to go through the PS tool box just because everyone else seems to. You will always benefit from the minimum of processing, often levels until you can see the detail coming through (2-4 iterations) then fine tune in Curves. The golden rule is; if you can see that something has been done then it has been done badly.

Some tips here Astrophotography

Dennis

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  • 2 weeks later...
  • 2 weeks later...

After many iterations of levels and curves (progressively fine-tuned) I tend to do some fine tuning on color balance (I occasionally have to tweak one filter or another thanks to clouds or what-not causing the imaging session to be cut short and one color not having quite as much data). Then I will do some layer masking depending on the object and occasionally some fine noise reduction (either by hand or with Noise Ninja) ... the key with PS is, as said above, not to overdo it as that can easily be done with all the various "tools" available in there.

Play around with various techniques, you will find out what you like to use the best and in which order.

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Levels is the place to be watching colour balance. Are you cutting back the colours individually in levels to keep the peaks (top left) in about the same place? As Dennis has said elsewhere, you also need to be looking at the picture! Leave plenty of space to the left of the main peak because it will mysteriously disappear as you play around with contrasts etc. Your final cut back should be at the end. I'm guilty of not doing this and tending to clip the black point.

After that, the key thing is to work in different zones of the image. Where you have a lot of strong signal you can sharpen. Where the signal is low (and you are not going back for more data which is what you should do!!) then some noise reduction may help. You may also want to separate the stars from anything done to the background.

So... all this means you need to master the selection tools. I use,

-Martin B's star layer creation or Noel's Actions to isolate stars.

-Highly feathered lasso

-Colour select to pick zones by colour

Where you have a high dynamic range you can simply do a second short stretch in Levels and curves looking at, for example, a bright galaxy core. When the core is right but the rest is still underexposed you stop and layer the short stretched core onto the fully stretched main image, discarding what you don't want. The erasor is very useful for removing, the stuff you don't want.

Never crop the image during processing or you can no longer drop a re-stretch back onto the work in progress.

Olly

Edited by ollypenrice
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I guess I should have specified that I use levels to do my color balancing ... I see I did not make that clear. I consider using levels on the final stack different in my mind of how I process than using levels for color balancing. So basically I agree with Olly :)

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