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Frequency Separation is evil

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  #21  
Old 12-23-2014, 03:25 PM
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Doug Nelson Doug Nelson is offline
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Re: Frequency Separation is evil

A couple of posts have inspired an interesting experiment for any interested parties to participate in:

1) Take a good but unprocessed starting photo
2) Perform your goto FS technique without any further work using your typical settings
3) Zoom in to a critical area on both the original and your recompiled FS version
4) Post both versions in this thread (zoomed to accommodate attachment limitation)

Let's see if there's no ocular difference. A side-benefit will be seeing what different folk consider a "critical area". Details on the technique and settings used appreciated, but optional. Matching zoom posts of individual separations even further appreciated, but even more optional.
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  #22  
Old 12-23-2014, 03:33 PM
Flashtones Flashtones is offline
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Re: Frequency Separation is evil

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Originally Posted by klev View Post
I would have to create a synthetic example to show that, because I never preserved any results after loosely testing it.

Go for it.
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  #23  
Old 12-23-2014, 03:45 PM
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Benny Profane Benny Profane is offline
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Re: Frequency Separation is evil

I don't know. Kinda busy. Six girls for next Tuesday. No time for testing.

Happy Holidays!
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  #24  
Old 12-24-2014, 02:02 AM
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Re: Frequency Separation is evil

Quote:
Originally Posted by Doug Nelson View Post
A couple of posts have inspired an interesting experiment for any interested parties to participate in:

1) Take a good but unprocessed starting photo
2) Perform your goto FS technique without any further work using your typical settings
3) Zoom in to a critical area on both the original and your recompiled FS version
4) Post both versions in this thread (zoomed to accommodate attachment limitation)

Let's see if there's no ocular difference. A side-benefit will be seeing what different folk consider a "critical area". Details on the technique and settings used appreciated, but optional. Matching zoom posts of individual separations even further appreciated, but even more optional.
I think this test may be doomed to failure in that it will only highlight the effects of bad technique or overuse of FS. Surely the only scenario in which there would be no ocular difference is one where no work beyond the actual separation has been done.

Also there are quite a few variables that come under the broad heading of Frequency Separation, for example - Inverted High Pass (Degrunge) techniques; 16 bit Apply Image techniques; Band Pass (Band Stop) used with global or local blurring, Separations for precise work on individual High and/or Low Frequency layers; Skin Smoothing plugins, e.g. Imagenomics Portraiture etc etc

I agree that FS is used a lot, and often badly, as a shortcut, and I also agree that many retouchers overuse FS techniques, or use them when other, more traditional approaches are perfectly effective and often quicker.

One of the reasons for this may be that, because it takes quite a bit of time and practice to perfect the numerous FS techniques available, most retouchers who start to use FS go through an extended period of using/overusing it while effectively learning on the job. I know I did.

I suppose you could identify some broad categories of FS usage as follows:-

1 Not used at all. 2 Used but "invisibly" 3 Used lightly 4 Used conspicuously, but skilfully for a particular look 5 Overused/Badly Used

Regarding the argument that it would never be used on the cover of Vogue - there have been some fairly disastrous examples of retouching that have found their way into the pages and onto the covers of the major magazines over the years, so I don't think this is necessarily a good yardstick.

Another thing that I'll mention in passing is the mathematical approach to analysing FS, Gaussian Blur etc which appears so often in this forum. I have great admiration for those who understand and put this level of knowledge into practice, and without such people we wouldn't have Photoshop (or even computers!). But I don't agree that everyday visual issues should be arbitrated on the basis of floating points and theoretical calculations. In the end, if it looks good it is good, and if you can't actually see the difference then there effectively is no difference.

Happy Christmas to everyone.
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  #25  
Old 12-24-2014, 01:27 PM
Flashtones Flashtones is offline
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Re: Frequency Separation is evil

Nice contributions AKMac. Lovely portfolio too.

Doug, I suggest that you do a show with AKMac, if he is willing, on the topic of FS. How to do it, how to choose a radius, when/where in the workflow to do it, how to do it subtly, how others go too far with it, telltale signs of overuse, etc. Move the conversation away from slurs, innuendo and dares, and into something practical and useful. Another tool in the toolbox.
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  #26  
Old 12-24-2014, 01:58 PM
klev klev is offline
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Re: Frequency Separation is evil

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Originally Posted by Flashtones View Post
Go for it.
I looked. I didn't have anything that I could use and that would show the example. I needed something where it would obviously show up (hair against a a plain seamless so you would see the haloing on the seamless). Anyway I'll be back in about 3 days. If anyone posts something like that I'll show what i'm referring to, but I grow bored looking for an image just to make a forum post.
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  #27  
Old 12-24-2014, 02:15 PM
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Re: Frequency Separation is evil

Quote:
Originally Posted by Flashtones View Post
Nice contributions AKMac. Lovely portfolio too.

Doug, I suggest that you do a show with AKMac, if he is willing, on the topic of FS. How to do it, how to choose a radius, when/where in the workflow to do it, how to do it subtly, how others go too far with it, telltale signs of overuse, etc. Move the conversation away from slurs, innuendo and dares, and into something practical and useful. Another tool in the toolbox.
Not a bad idea.

Alastair, if you're game email me and we'll set it up.
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  #28  
Old 12-24-2014, 02:43 PM
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Re: Frequency Separation is evil

I'm flattered by the suggestion, but there are others who are far better qualified than I am. I think it's a great idea though.
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  #29  
Old 12-25-2014, 12:05 AM
skoobey skoobey is offline
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Re: Frequency Separation is evil

lara-beauty7.jpgOK. You want proof? There is proof. A pointless proof. It's like saying that a single grain of salt in a pot of stew will make it or brake it. It won't.

So, we take a flat file, duplicate it, and set it to difference blend mode. Those two are identical. If we make a threshold adjustment layer, and set tolerance to one, image stays black.

If we make a separation, set it to difference blend mode, and put a threshold over, we'll see that there is actually a lot of pixels that don't have the same levels like the original.

But, we want to change the image anyway quite considerably, so think about the overall result, not why this or that is bad.
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  #30  
Old 12-25-2014, 02:04 AM
Flashtones Flashtones is offline
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Re: Frequency Separation is evil

Agreed, skoobey, on all counts, especially that it's a pointless proof. It reveals the mathematical difference we know exists, but you have to create a perfect storm of ridiculous extremes to reveal it.

More realistic visual demonstrations would include: 1) showing the split image side by side with the the un-split image, in normal mode, and see if people can tell which is which. Or 2) do the difference mode trick but without the threshold adjustment, so they will see the the black one expects from no discernible difference, or 3) keep the threshold adjustment layer but without the difference mode to show you've posterized the image to smithereens to get the effect.

All I can say is that people who are overly concerned with altering the content of an image to any degree probably shouldn't be in the retouching business, which is predicated on image alterations. It'd be like someone taking a flawlessly performed Doge and Burn job and pointing to a couple of spikes in the histogram and declaring that technique a failure on said grounds.
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