CM and Photoshop's Shadows/Highlights command

This is the forum for posting to the June 2010 CM 101 Class
imported_BoydMac
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Joined: Sat Jan 10, 2009 3:19 am

Postby imported_BoydMac » Sun Jul 25, 2010 4:13 am

I have found Photoshop's shadows/Highlights command to be very useful.  I expected to be able to accomplish the same transformation by adjusting the curves in Curvemeister.  I have not been able to do so and wonder why.  Take for instance the Taroko Gorge image.  If I get aggressive with the folage correction, all detail in the river bed rocks is lost and no adjustment the the curves that I tried would bring it back.  The S/H command did it easily. Likewise, when I tried to bring out detail in the tree and rocks in the forground of the  tainan-park-of-5-concubines image, I got what I assume to be posterization.  Again, the S/H command solved the problem.  Is there a straight forward way to accomplish the same result within Curvemeister?
Attachments
cm101-wk-6-tainan-park-of-5-concubines-adj-jpg
cm101-wk-6-tainan-park-of-5-concubines-adj-jpg (999 Bytes) Viewed 14270 times
cm101-wk-6-taroko-gorge-taiwan-adj2-jpg
cm101-wk-6-taroko-gorge-taiwan-adj2-jpg (999 Bytes) Viewed 14270 times

ggroess
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Postby ggroess » Sun Jul 25, 2010 2:10 pm

Let me think on this one a bit...There are things you can do...they might not be as effective at first glance...

I'll try to post an example with ACV files for you...

Greg

derekfountain
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Joined: Fri Jan 26, 2007 1:24 pm

Postby derekfountain » Sun Jul 25, 2010 5:09 pm


I have found Photoshop's shadows/Highlights command to be very useful.  I expected to be able to accomplish the same transformation by adjusting the curves in Curvemeister.  I have not been able to do so and wonder why.  Take for instance the Taroko Gorge image.  If I get aggressive with the folage correction, all detail in the river bed rocks is lost and no adjustment the the curves that I tried would bring it back.  The S/H command did it easily. Likewise, when I tried to bring out detail in the tree and rocks in the forground of the  tainan-park-of-5-concubines image, I got what I assume to be posterization.  Again, the S/H command solved the problem.  Is there a straight forward way to accomplish the same result within Curvemeister?


My take is that the answer is "no". The shadows/highlights filter uses a sophisticated algorithm which takes into account surrounding pixels and a number of inputs (the sliders on the dialog). It's a lot more complex, and IMHO, a lot more capable than a simple curve manipulation.

My standard workflow (when I use CM) is to use the RAW filter to ensure the image uses the full range (i.e. no empty gaps at either end of the histogram), then run S/H in LAB mode,  correcting plugged shadows and blown highlights without affecting the colours. I then use CM to fine tune the shadows and highlights and to get the colours right.

mikemeister_admin
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Joined: Fri Sep 20, 2013 8:29 pm

Postby mikemeister_admin » Sun Jul 25, 2010 7:19 pm

I usually use s/h(with color correction set to 0) instead of a lizzard tail now.I'm speaking as a hobbyist,not someone who has to satisfy clients or pressmen.GJM
For this image I went crazy with the color slider in s/h.
Attachments
2007-11-park-of-5-concubines-copy-2-jpg
2007-11-park-of-5-concubines-copy-2-jpg (267.66 KiB) Viewed 14270 times

[The extension shh has been deactivated and can no longer be displayed.]

2007-11-24_105050-tainan-park-of-5-concubines-copy-2-lab-acv
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leeharper_admin
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Joined: Tue Aug 20, 2013 2:39 pm

Postby leeharper_admin » Sun Jul 25, 2010 8:38 pm

There are much better alternatives to Shadow/Highlight that do similar things. I use it with mild settings when I'm in a hurry, and not particularly concerned about getting the best quality out of the file. When that's not the case there are more effective strategies that can be employed.

It's getting a little late here - I'll post some suggestions tomorrow ;)
Lee.

ggroess
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Postby ggroess » Mon Jul 26, 2010 2:20 am

There are all kinds of hammers out there for driving many different nails...I would say that CM can help drive a few of them but in some cases we are finding that CM is not the answer...As we quantify what that really means... I and others are working on getting more information into the class regarding how to best handle some of these images.

I would say that I too use S/H for some of the tough images...I generally use a layer and do some sort of blending after the S/H command is done with it's math.  If that does not work there is always ACR there are also some HDR converters that can help with the settings chopped down to minimums...

Boyd...Every image I wanted to post with an ACV could be handled better elsewhere...these are the extreme images that need serious help...Curves in general can do some amazing things...they are just not always the right tool for the job...

Greg

mikemeister_admin
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Postby mikemeister_admin » Mon Jul 26, 2010 3:23 pm

Hi Boyd,

Lets split Shadow/Highlight in half.

If we assume that we would like to lighten the shadows within an image, we can either use the method I'm going to discuss for highlights, or we can apply a false profile. Dan Margulis invented both techniques as far as I know, and in this case he has written up the whole process:
http://www.ledet.com/margulis/Makeready/MA48-Fate_and_False.pdf. I used this technique on the tainan-park-of-5-concubines image last week.

I posted a feature request to ask Mike to build this functionality directly into CurveMeister (http://www.curvemeister.com/forum/index.php/topic,3120.0.html) - amongst other things... If you think that this would be helpful perhaps you could give him a nudge ;)

What to do about darkening highlights? See the next post...  :)

leeharper_admin
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Postby leeharper_admin » Mon Jul 26, 2010 3:49 pm

Ok, darkening highlights... Before you read this, take a look at the image I've attached.

The top image uses the Shadow/Highlight command to darken the highlights (the amount slider is cranked up to 100%). I couldn't find a better example image. It could be argued that S/H makes the boulders look ok, but as you can see from the version underneath, there is more that can be done for them.

The bottom version is a very mild application of Dan Margulis' 'Overlay blend' technique. There are some videos at KelbyTraining that explain the process (www.kelbytraining.com/instructors/dan-margulis.html), but you need a subscription to watch them, so I'll give you a brief outline of the process.

Lets take this image. We need to take a look at the channels (so, as far as I know, you can't do this in Photoshop Elements). Select: Window > Channels if your Channels panel is not open. Click in turn on the Red, Green, and Blue channels - one at a time. We are trying to find out which channel (in this case) contains the darkest trees and the brightest boulders. In this image the Red channel is the best choice. Having determined this, we are ready to blend:



  • Create a new layer above your current layer(s)

  • Choose: Image > Apply Image...

  • Select 'Red' from the 'Channel' drop-down menu

  • Select 'Normal' from the 'Blending' menu

  • Click 'OK'



You will now have a B/W layer (a copy of the Red channel) at the top of your image's layer stack. Invert this layer (Image > Adjustments > Invert). Doing this will make the trees light, and the boulders dark. At this point there are only a few more things to do:



  • Change the blend mode of this layer to 'Overlay' (in the Layers panel)

  • Don't panic!



Changing the blend mode of our layer to overlay will get you back 'towards' a normal image - but it'll make the image look (temporarily) awful. Don't worry about that - there's just one final step:

We need to blur the layer - Filter > Blur > Gaussian Blur. Start with a blur value around 30 pixels, and then adjust up and down to see the effect of the blur (it will add dimension to the boulders). I left the blur at 30 px for the image attached...

This process will mimic S/H - it will lighten the dark areas, and darken the light areas. If you want to completely omit the lightening, duplicate the layer beneath the overlay layer we just created. Place the duplicate above the overlay layer, and set its blend mode to 'Darken'. You can change the opacity of the 'Darken' layer if you want to partially lighten the trees. Another area where you can control the effect is by curving the overlay layer.

It sounds like a lot of work to do this, but in practice it only takes about 15 seconds to do this by hand - and you can always write an action to speed the whole thing up.

Let me know if it works for you :)
Lee.
Attachments
shadowhighlightalt-jpg
shadowhighlightalt-jpg (298.37 KiB) Viewed 14270 times

imported_BoydMac
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Postby imported_BoydMac » Mon Jul 26, 2010 4:55 pm

Lee - thank you again.  I will learn to do this since it seems to do a better job.  Likewise for the focus sharpening.  I have read some of Dan Margulis' books but never really put them into practice.  Working with curves has been a big barrier.  It seemed a lot easier to screw things up than to improve them.  This class has taken me through that barrier and you have broadened the perspecitve.

leeharper_admin
Posts: 263
Joined: Tue Aug 20, 2013 2:39 pm

Postby leeharper_admin » Tue Jul 27, 2010 7:45 am

No problem at all Boyd :)

I feel exactly the same way - whenever I've read Dan's books in the past I have been frustrated by how difficult curves were to manage. Like you whenever I attempted to use curves (which always made sense when I read about them) I would end up messing the image up. Having that barrier removed feels really empowering!

Now that I feel comfortable using curves, all that's left to do is figure out when I should!

I really enjoy participating in this community, so I will be on the forum quite frequently I'm sure. If there is anything that you would like an opinion on please post something - I'll help out if I possibly can. :)

Lee.


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