RetouchPRO

Go Back   RetouchPRO > Technique > Photo Retouching
Register Blogs FAQ Site Nav Search Today's Posts Mark Forums Read


Photo Retouching "Improving" photos, post-production, correction, etc.

Automatic Skin Smoothing.

Reply
 
Thread Tools
  #91  
Old 11-02-2010, 09:14 AM
ShadowLight ShadowLight is offline
Senior Member
 
Join Date: Oct 2009
Posts: 397
Re: Automatic Skin Smoothing.

Quote:
Originally Posted by bakerser View Post
The "shift" (which isn't a shift - moving towards 127.5 is the "shift") is based on the input image mean. I'll post a formula for you if it'll help you.
having 167 instead of 127/8 is a shift, no matter how you look at it.
(this was proven with tests, I got results from 145 to 167 when I tested it with a few different images)


Sean, stop trolling and spreading misinformation.

If you show your IHP is better than what I use (with a PSD comparison) I will gladly comment on it. If you need help with understanding why using Alpha works, or any other contested issue I will explain it to you in private, just ask.
Reply With Quote top
  #92  
Old 11-02-2010, 09:17 AM
bakerser bakerser is offline
Member
 
Join Date: Jan 2008
Posts: 91
Re: Automatic Skin Smoothing.

Quote:
Originally Posted by Flashtones View Post
I have yet to see side-by-side comparisons of say, your IHP action vs Shadowlight's tools. If it's advantages are obvious it shouldn't be hard to demonstrate visually. Doing so would go a long way here.
I'll post a visual of the difference tonight, though it'll have to be a synthetic - I don't have any beauty material ATM. Suffice, the problem with naive HP is detail clipping. So if we're using HP to extract the detail which we wanted to remove, we end up losing a lot of it. At the end of the day I heartily agree to doing what makes you (& the client!) happy, but want to make sure that folks understand what they're really using here.
Reply With Quote top
  #93  
Old 11-02-2010, 09:27 AM
Flashtones Flashtones is offline
Senior Member
 
Join Date: Apr 2009
Posts: 956
Re: Automatic Skin Smoothing.

Quote:
Originally Posted by bakerser View Post
I'll post a visual of the difference tonight, though it'll have to be a synthetic - I don't have any beauty material ATM.
You have a lovely portfolio of beauty images, and since this thread is about skin work I think a real world application would be best.
Reply With Quote top
  #94  
Old 11-02-2010, 09:48 AM
lolli lolli is offline
Member
 
Join Date: Oct 2008
Posts: 78
Re: Automatic Skin Smoothing.

Any hope of getting it for cs3? thanks Pat
Reply With Quote top
  #95  
Old 11-02-2010, 09:48 AM
bakerser bakerser is offline
Member
 
Join Date: Jan 2008
Posts: 91
Re: Automatic Skin Smoothing.

Quote:
Originally Posted by ShadowLight View Post
having 167 instead of 127/8 is a shift, no matter how you look at it.
(this was proven with tests, I got results from 145 to 167 when I tested it with a few different images)
Did you compare those means to the original mean for the image? It would seem not.
Quote:
Originally Posted by ShadowLight View Post
If you show your IHP is better than what I use (with a PSD comparison) I will gladly comment on it.
Didn't I give you a PSD on MM?
Reply With Quote top
  #96  
Old 11-02-2010, 09:52 AM
bakerser bakerser is offline
Member
 
Join Date: Jan 2008
Posts: 91
Re: Automatic Skin Smoothing.

Quote:
Originally Posted by Flashtones View Post
You have a lovely portfolio of beauty images, and since this thread is about skin work I think a real world application would be best.
While I appreciate the flattery, it doesn't change the fact that I don't have access to that material right now and likely won't for the rest of the week. So, to give you an example sooner than later, it will have to be from what o can create in PS or download easily. Sorry, but my main system is supporting a deploying spouse ATM.
Reply With Quote top
  #97  
Old 11-02-2010, 10:05 AM
ShadowLight ShadowLight is offline
Senior Member
 
Join Date: Oct 2009
Posts: 397
Re: Automatic Skin Smoothing.

Sean, stop trolling.
if you need help, ask on private


Quote:
Originally Posted by lolli View Post
Any hope of getting it for cs3? thanks Pat

those kind of interfaces were not supported before CS4 if I'm not mistaken
sorry, nothing can be done about it

Last edited by ShadowLight; 11-02-2010 at 10:24 AM.
Reply With Quote top
  #98  
Old 11-02-2010, 10:50 AM
Flashtones Flashtones is offline
Senior Member
 
Join Date: Apr 2009
Posts: 956
Re: Automatic Skin Smoothing.

Quote:
Originally Posted by bakerser View Post
While I appreciate the flattery, it doesn't change the fact that I don't have access to that material right now and likely won't for the rest of the week. So, to give you an example sooner than later, it will have to be from what o can create in PS or download easily. Sorry, but my main system is supporting a deploying spouse ATM.

No prob. Good luck to your wife.
Reply With Quote top
  #99  
Old 11-02-2010, 01:16 PM
bakerser bakerser is offline
Member
 
Join Date: Jan 2008
Posts: 91
Re: Automatic Skin Smoothing.

Quote:
Originally Posted by Flashtones View Post
No prob. Good luck to your wife.
OK, so I've gone a middle road for this example - a real image from my portfolio, but not additionally / re - processed for skin. Rather, just a real image of a real person to illustrate a point. Some explanation is in order lest this demo be creatively misconstrued:
  1. The whole point of IHP and related processes is to selectively remove a frequency band of detail by applying its inverse to it. As no one has (yet) contested that Gaussian Blur or Inverse have multiple modes of operation, I've left these out of the discussion and provide only multiple forms of HP result. That is, all which we are comparing is the difference between creating a High Pass result after a -50% Contrast move and doing so after a -50% Opacity move.
  2. Given the above (needing detail in order to eliminate it), any loss of detail in the HP layer will result in our inability to effect a controlled removal of it. Think about it - if I want to remove the details from say 5px to 15px, and all that detail were to be clipped to 0 or 255 in HP, I no longer have the ability to remove it from the original - I can only make the entire (clipped) area brighter or darker. And as we all learn early in our photographic & retouching journeys, clipping of either highlights or shadows decidedly and irrecoverably destroys detail [excepting RAW / FP data, which isn't relevant here].
  3. For the sake of visualization, I have included two aids to make the difference more visible from the get-go. The first is a 50% gray layer which lies underneath the -50% Opacity version, so as to give you a gray-backed comparison between the two. The image is in 16bpc, so the 50% gray layer truly is entirely neutral and only keeps you from seeing the checkered background / the original image. The second is a contrast-boosting levels adjustment layer which sits above everything else. You can still see the difference (especially in the histogram) without it on, but is available simply as a visual aid.
  4. Note that the -50% contrast version retains a full tonal and color range throughout the image surface. This is both directly visible as well can be inferred from watching the histogram - note the hard highlight edge which the -50% Opacity version creates when it clips data in its processing. Doing the math, for this image the -50% Opacity layer actually costs us the ability to retain (or, further down the road, selectively remove) detail over a full 11.4% of the image area!
  5. Jonas (DerW) over at MM suggested that a sort of 'compromise' might exist in switching the -50% Opacity to -50% Fill. Some of you may not know, but this actually represents a significant difference in the way that PS does its image math (even though it often looks identical). Here still, though, data clipping occurs due to the way that PS handles the transparency calculations. It appears that PS chooses to use the whole (non-alpha-corrected) numbers up front (causing the clipping) and then blending the result back at the original opacity value -- that vs. reducing the numbers up front by the alpha value, calculating, and then returning the whole result. It wouldn't be a bad idea to ask Adobe to change that, as it has implications for other things which we can't as easily do through PS, but that's another discussion for another thread.
  6. If you just want to cut to the chase, the two histograms below tell the story. The one on the left is the post-HP histogram of a -50% Contrast copy of the image. The one on the right is the post-HP histogram of a -50% Opacity image. That spike on the right is what's known in technical fields as Bad .

Please let me know if this helps explain things to you as to why the difference can be so important, and the well wishes are greatly appreciated.

PSD
Attached Images
File Type: jpg HPDemoHistos.jpg (84.1 KB, 21 views)

Last edited by bakerser; 11-02-2010 at 02:15 PM. Reason: Typos, again!
Reply With Quote top
  #100  
Old 11-02-2010, 02:30 PM
ShadowLight ShadowLight is offline
Senior Member
 
Join Date: Oct 2009
Posts: 397
Back to reality

Sean, unfortunately reality is not so clear cut...

When you actually implement the two separate techniques you do get this result: (see attached pic)
as you see contrast -50 does not give you a 127/8 grey, in this case is more like 154/5.


Using Contrast -50 shifts the lum.
This means that for the same texture different corrections will be created depending on the "whole" of the image (ie on the surrounding content)...

... if you have a portrait of the same person, but once on white background and another on black background, when you start to smooth the skin the corrections will be very different and "wrong" for the texture.

Second, SkinSmooth actually uses "Fill" and there is no clipping whatsoever.

That said... Sean... thanks for the trolling, and as I said if you have questions do it in private. I look forward to the time when you will actually show how SkinSmooth compares in practice with the technique you are so found of.

BTW, Congrats on the upcoming delivery. You should get some sleep now when you can.
Attached Images
File Type: jpg contrast-vs-skinsmooth.jpg (89.4 KB, 17 views)
Reply With Quote top
Reply

  RetouchPRO > Technique > Photo Retouching


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Glamour retouch challenge here!!!! superkoax Photo Retouching 332 02-08-2011 09:52 PM
Automatic Skin Tone Retouching - Seeking feedback Pixarra Photo Retouching 15 11-09-2010 01:38 AM
Skin Smoothing Technique (Again) Novi Photo Retouching 10 10-16-2008 04:25 PM
need help doing pageant eyelashes and skin smoothing w/ photoshop cs sandylavallie Photo Retouching 3 05-06-2005 08:53 AM
skin smoothing action john_opitz Photo Retouching 10 08-21-2002 10:48 PM


All times are GMT -6. The time now is 06:45 PM.


Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
SEO by vBSEO ©2011, Crawlability, Inc.
Copyright © 2016 Doug Nelson. All Rights Reserved