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Lab sharpening;
  
 
ben egbert
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p.1 #1 · Lab sharpening;


I am reading Photoshop Lab color by Dan Margulis. Just up to chapter 4 so far but already seeing improvements in my work.

He suggests sharpening in LAB on the lightness channel. So I have been applying my favorite sharpening steps, which are 12,50,1 followed by 300, 0.3, 0 all on one layer and then faded to 70%

I do this after adjusting the L, A and B channels and of course after any NR.

There are usually some additional steps after I exit LAB. And in my previous workflow I sharpened at the end.

I have a hard time seeing any difference between sharpening in LAV and in RGB.

Questions:

1.When using LAB sharpening, should I finish al work before applying or is it ok to do it when I am finished with my LAB exposure/color work?

2.What are the advantages of using LAB sharpening?

Note, I canít remember the last time I used selective sharpening other than sometimes avoiding sky. I donít work on soft images.



Mar 12, 2014 at 05:36 PM
Picture This!
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p.1 #2 · Lab sharpening;


Sharpening is typically applied as the last step along with downsizing for web presentation.

When you sharpening using the "L" or lightness channel you are only affecting luminosity without impacting any of the color info.



Mar 12, 2014 at 05:52 PM
Peter Figen
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p.1 #3 · Lab sharpening;


For all practical purposes, sharpening in RGB and Fading to Luminosity accomplishes the same thing. For me, since Lab is usually an intermediate step in the process long before final output, I never actually sharpen in Lab anymore.


Mar 12, 2014 at 07:33 PM
Mirek Elsner
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p.1 #4 · Lab sharpening;


... or do the sharpening in RGB on a layer and set the layer interaction to Luminosity. Also (pretty much) the same thing as doing it in Lab on the L channel.


Mar 12, 2014 at 08:15 PM
ben egbert
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p.1 #5 · Lab sharpening;


Mirek Elsner wrote:
... or do the sharpening in RGB on a layer and set the layer interaction to Luminosity. Also (pretty much) the same thing as doing it in Lab on the L channel.



Ok, I expected am answer along these lines. Just wanted to know what others were doing.

Thanks to all responders.



Mar 12, 2014 at 08:29 PM
redcrown
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p.1 #6 · Lab sharpening;


"For all practical purposes" and "Pretty much the same thing" are accurate statements.

However, there is a difference between working on the L channel in LAB and working on an RGB version in Luminosity mode. The reason is that the LAB L channel is a different luminosity version of the image than luminosity modes in RGB.

The contrast between light and dark areas along an edge will be different. Since sharpening depends on this contrast, the sharpening results will be different. On most images, that difference will be very small. Usually not even visible on screen or in a print.

But the difference is image dependent. On images with bright, highly saturated colors, the difference may be more significant (yet still small). Whether that difference is better or worse is a matter of personal preference.

Even if you find the LAB method preferable, you need to ask if that advantage is worth the extra effort to make the round trip to LAB.



Mar 12, 2014 at 08:57 PM
ben egbert
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p.1 #7 · Lab sharpening;


One more question. The author has a reversed direction when in the curves dialog box. He uses darkness on the left and lightness on the right. Just the opposite of my default.

He says you can click in the gradient bar below the grid to swap it, but this does not work in CS6. His book is using and older version.

I have looked in all the usual places for a way to swap it. I can follow his examples by turning his book upside down. But it would be nice if I could just swap it.




Mar 13, 2014 at 01:05 AM
Eyeball
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p.1 #8 · Lab sharpening;


In the Curves Display Options, click "Pigment/Ink %" instead of "Light".

Curves Display Options are available at the bottom of the Image>Adjustment>Curves window or by clicking the little drop-down icon at the top of the Curves Adjustment Layer window.



Mar 13, 2014 at 01:15 AM
ben egbert
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p.1 #9 · Lab sharpening;


Got it, thanks now its working.


Mar 13, 2014 at 01:57 AM
Peter Figen
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p.1 #10 · Lab sharpening;


Even when I'm working in CMYK, I always want my Curves set to have dark and lower left and light at upper right. Just seems to make more sense to me that way.

Also - take what Dan says for what it's worth. You don't have to do exactly as he does. Borrow what works for you and apply it to your images in the way that seems to make them better.



Mar 13, 2014 at 02:34 AM
 

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ben egbert
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p.1 #11 · Lab sharpening;


Peter Figen wrote:
Even when I'm working in CMYK, I always want my Curves set to have dark and lower left and light at upper right. Just seems to make more sense to me that way.

Also - take what Dan says for what it's worth. You don't have to do exactly as he does. Borrow what works for you and apply it to your images in the way that seems to make them better.



Hi Peter. I am trying to burn into my brain the red>green relationship and yellow>blue. Doing the examples in the book using the images supplied on the DVD helps, but it is a real bummer to have to turn them upside down.

Also the relationship between cool and warm and the method of altering part of a curve to fix color casts is something I really want to understand.

Someday I will probably flip it back after I read the book.

I use a PC and never use hot keys, in fact I hate them to high heaven because my two finger typing often hits one by mistake and sends me to some place where I can't get back.

So far the thing that eludes me is color numbers. He shows screen shots showing LAB values that he must have set with the eyedroppers but never show how or where he put them. It would be useful to get a feeling for the amount of changes being made.



Mar 13, 2014 at 02:06 PM
newhaven
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p.1 #12 · Lab sharpening;


What page are you looking at?


Mar 13, 2014 at 02:38 PM
ben egbert
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p.1 #13 · Lab sharpening;


try page 7 fig 1.5 and page 44 fig 3.5 and page 65 fig 4.4. But he often uses color values in the text.


Mar 13, 2014 at 03:07 PM
newhaven
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p.1 #14 · Lab sharpening;


On page 7, he is just moving the eye dropper tool over an area of interest to find it's general location on the curve. If you select the targeted adjustment tool in the curves dialog panel, the location of the cursor or eye dropper tool will be displayed along the curve as a small circle. The targeted adjustment tool is located directly above the set black point tool.

I have this book, and there are a lot of useful concepts and techniques, but the information is a lot easier to grasp in the Picture Postcard Workflow series at kelby.



Mar 13, 2014 at 03:57 PM
ben egbert
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p.1 #15 · Lab sharpening;


I have 5-6 books on photoshop Kelby among them. I often find books pretty dense but I am doing ok with this one. Anyway, thanks for the tip and I may head over there after I get finished with this one.

I have figured out how to put eyedrop markers on the curve, although I always forget the exact icon and sometimes get one that locks me out of everything. I need more practice. Like my passwords, I need to write it down and put it on my desktop to remember it. Or else do it a few dozen times to get it into long term memory.



Mar 13, 2014 at 06:22 PM
newhaven
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p.1 #16 · Lab sharpening;


The Picture Postcard Workflow series is presented by Margulis so it's not a typical kelby production, but the book is good also.


Mar 13, 2014 at 06:36 PM
Mirek Elsner
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p.1 #17 · Lab sharpening;


Yes, the series by Margulis on kelbytraining is great. It is still good to have the book - at least for me it was difficult to remember all his tricks. There are some other interesting videos by other authors, it is worth looking at.


Mar 13, 2014 at 06:52 PM
Imagemaster
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p.1 #18 · Lab sharpening;


No need to sharpen a layer or do in LAB.

Just Sharpen, then Edit > Fade Sharpen > Mode - Luminosity



Mar 14, 2014 at 01:33 AM
Bifurcator
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p.1 #19 · Lab sharpening;


I still use LAB sharpening in my script. Since it's a script I don't have to do anything so it's not any more or less work. The script changes the Mode to Lab, selects the Lightness channel for editing and turns on all channels for viewing. So I see a color image in the PS image window and a monochrome image in the Smart Sharpening tool window. And of course as with all my scripted steps the Fade tool comes up right after.

The "Fade Sharpen > Mode - Luminosity" method will NOT produce the same results - obviously! It will be sharpening each and every channel of RG & B which will produce a lot more halo affect - even when applied only as luminance values. This may be good enough in some cases but it's not the same.

I think you have a copy of my script Ben, so you can just take a look-see if you're interested is what all I do and when it gets done in the progression of processing the image.







Mar 14, 2014 at 03:38 PM
ben egbert
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p.1 #20 · Lab sharpening;


Bifurcator wrote:
I still use LAB sharpening in my script. Since it's a script I don't have to do anything so it's not any more or less work. The script changes the Mode to Lab, selects the Lightness channel for editing and turns on all channels for viewing. So I see a color image in the PS image window and a monochrome image in the Smart Sharpening tool window. And of course as with all my scripted steps the Fade tool comes up right after.

The "Fade Sharpen > Mode - Luminosity" method will NOT produce the same results - obviously! It will
...Show more

I do, but before looking for it, I wrote my own action only using my sharpening steps which I was already using in RGB.

I find that sharpening a well focused full size ISO100 landscape to be something that I can do globally and the same every time. So I don't need to fade selectively, I just go to lab, luminosity and run the sharpening steps fade 70% which I find ideal and go back to RGB. All in one action.I could leave the action in LAB for fading and may do that in future, but see no need at this time.

If I have a problem image, (high iso) I will do the sharpening steps manually. If I have a blended image with difficult DR, I usually run a fairly aggressive NR on the dark areas and sky's before proceeding, and can then do my normal sharpening later.

I take great care on focus, use Canons best lenses and discard those with focus issues. I also have a pretty narrow range of style.



Mar 14, 2014 at 04:27 PM
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