RetouchPRO

Go Back   RetouchPRO > Tools > Software
Register Blogs FAQ Site Nav Search Today's Posts Mark Forums Read


Software Photoshop, Lightroom, Paintshop Pro, Painter, etc., and all their various plugins. Of course, you can also discuss all other programs, as well.

First steps towards a new adjustment tool

Reply
 
Thread Tools
  #11  
Old 06-03-2015, 06:06 PM
pixaeiro pixaeiro is offline
Member
 
Join Date: Feb 2015
Posts: 32
Re: First steps towards a new adjustment tool

Hi Doug
I spent some time investigating this problem, and the best I came up with ended up being a linear transformation (think curves with just 2 points), which could convert a black shoe into a white shoe, but I doubt is what you have in mind.
Do you any other examples? Or maybe a graph that describes what you have in mind?
Reply With Quote top
  #12  
Old 06-03-2015, 08:00 PM
klev klev is offline
Senior Member
 
Join Date: Jun 2010
Posts: 1,109
Re: First steps towards a new adjustment tool

Quote:
Originally Posted by pixaeiro View Post
Hi Doug
I spent some time investigating this problem, and the best I came up with ended up being a linear transformation (think curves with just 2 points).
Linear transformations are used in photo filtering, some adjustment tools. Whenever you convert between color profiles, that is a linear transformation. There isn't a known ideal way to map one range into another. You could employ some strategy for smoothing / relaxation of data, but that doesn't qualify it as a perfect gradient. There's also the issue that once you step away from photoshop, gradient means something completely different. When he says a perfect gradient, I think he means a gradient of constant value. It wouldn't result in what expects, but I think it's what he meant. Suppose you remapped the image to a linear rgb basis with values encoded relative to some measure of intensity. It would need some inverse mapping to be usable, but you could do this as long as you can establish a clean workflow(see scene referred color workflows). At that point you could could rescale the range per channel to match the desired end points and mean or median. In fact that has been tested and abandoned by multiple researchers before moving on to different methods. I could probably link some of the papers.
Reply With Quote top
  #13  
Old 06-03-2015, 08:34 PM
Doug Nelson's Avatar
Doug Nelson Doug Nelson is offline
Janitor
 
Join Date: Aug 2001
Posts: 7,068
Blog Entries: 21
Re: First steps towards a new adjustment tool

By "perfect gradient" I meant some standard that only exists in theoretical ("perfect") space. Probably a poor choice of words, I'm a bit like Homer Simpson trying to understand living in a 3D world. It could very well end up being a cube or something only roughly imaginable in the real world. The important point is to have a fixed standard with which to compare the 2 photos against. It might very well exist in some higher bit-depth range.

Premiere Pro has a scope which is sort of like a histogram only instead of just distribution it also shows location. So imagine a photo being raised up by the levels (and colors) involved depending on the amount of that particular value, then looking down on that. So the dark and light spots (in the case of Premiere, but we're talking some abstract model that also shows colors) not only show you how much of a tone exists but where it is located. I'm not saying this is the best way to do this, just as an example of a theoretical analysis space.

The important point is we'd be comparing two images to a fixed standard, so we'd be able to extract all sorts of information about the differences from that standard, then we could compare those differences and extract the necessary math to convert from one to the other.
Reply With Quote top
  #14  
Old 06-04-2015, 12:54 AM
klev klev is offline
Senior Member
 
Join Date: Jun 2010
Posts: 1,109
Re: First steps towards a new adjustment tool

I'm not sure why you mentioned Premiere. The feature you described is more common in applications aimed at editing video. It just gives you the equivalent of a histogram for each segment of a given image. It tends to provide somewhat more context, especially in scenes with variable lighting, but it still requires some interpretation.

Regarding geometric forms that aren't limited to 3 dimensions, hypersurfaces are a confusing topic, but they do come up in computer graphics. A lot of the stuff you mention is currently implemented in some way or an area of active research. For example computing differences between two things with respect to a given standard is currently done either via lookup table or linear transformation. ICC profiles actually use the latter. When you convert between them, the lookup is always with respect to a given profile connection space. If you wanted to remap one range of values to another based on measured values, you're back to an area of active research (and I can post many links). Also let me know if you want any crash course reading. I'm an obsessive reader.
Reply With Quote top
  #15  
Old 06-25-2015, 02:19 PM
pixaeiro pixaeiro is offline
Member
 
Join Date: Feb 2015
Posts: 32
Re: First steps towards a new adjustment tool

Quote:
Originally Posted by klev
I could probably link some of the papers.
That would be awesome! Thanks!
Reply With Quote top
  #16  
Old 06-25-2015, 04:24 PM
Tulack Tulack is offline
Senior Member
 
Join Date: May 2015
Posts: 191
Re: First steps towards a new adjustment tool

Black and white shoe is easy. What about colored shoe? Every part of it has not only value, but also hue and saturation. Also highlight of a black shoe would be white, how would you tell the mid point, from which nothing should be changed? White should stay white. Also output depends on input. If you target image slightly different from reference, it would look different even if you get numbers perfectly right.

People asking "how to" because they don't know, not because they don't have tools.

Last edited by Tulack; 06-25-2015 at 04:32 PM.
Reply With Quote top
  #17  
Old 06-25-2015, 05:51 PM
klev klev is offline
Senior Member
 
Join Date: Jun 2010
Posts: 1,109
Re: First steps towards a new adjustment tool

Quote:
Originally Posted by pixaeiro View Post
That would be awesome! Thanks!
See Erik Reinhard's site for one. I own one of his books, and he's an excellent writer. Most of his papers are reachable from that link. Francoise Pitie did some interesting work, treating pixel level transitions as a probability density function.

fast local color transfer via dominant colors mapping

I can't find an unprivileged link for Xiao and Ma. It provides some of the earlier work in gradient preserving mappings. The ones above are more digestible anyway. It's also worth reviewing the wiki on the LMS color space, which is frequently used for reference in examining methods of decomposing an image into visually orthogonal channels. If you're interested in the segmentation aspects, google soft scissors or poisson image editing (poisson's equation in case you're interested).

There are some books that might also help here, but anything really helpful won't be elementary reading.Others have attempted it in commercial products with my favorite being VSCO.

If you're interested in more fundamental books about color, see Wyzecki and Stiles, Mark Fairchilds, Noboru Ohta, Jan Morovic. For basic implementations of open source color engines, see littleCMS or ArgyllCMS. I'm not digging up links on each book, but I would suggest you try an academic library. The books are otherwise quite expensive. Wyzecki and Stiles is really a hardcore science book used primarily for reference. The papers also sometimes refer to math texts when explaining the breakdown of their algorithms. They don't do this with anything elementary, including probability. Anything I link there is going to be fairly hardcore.
Reply With Quote top
  #18  
Old 06-25-2015, 06:12 PM
klev klev is offline
Senior Member
 
Join Date: Jun 2010
Posts: 1,109
Re: First steps towards a new adjustment tool

Quote:
Originally Posted by Tulack View Post
Black and white shoe is easy. What about colored shoe? Every part of it has not only value, but also hue and saturation. Also highlight of a black shoe would be white, how would you tell the mid point, from which nothing should be changed? White should stay white. Also output depends on input. If you target image slightly different from reference, it would look different even if you get numbers perfectly right.

People asking "how to" because they don't know, not because they don't have tools.
I sometimes wonder how you reach these conclusions. You are veering into technical areas rather than artistic ones, and it's a bad idea.

Methods of automating a match relative to some metric have been attempted due to the labor cost of something which is ultimately tedious. Further hue, saturation, and value aren't completely decoupled in terms of human vision. A more modern way of looking at this would be one of examining cone response under a standardized model, as we can't completely control for visual processing. See LMS for one. I started to expand on that, but it's just too much material for a given post. The point was that yes there has been progress in automated variations on this. I linked one commercialized example in the previous post. That you can achieve the same thing today is irrelevant. I've altered colors by hand with various layers, masks, channel mixer, retinting bright reflections, etc. No one denied that was possible.
Reply With Quote top
  #19  
Old 06-25-2015, 06:27 PM
joe_7 joe_7 is offline
Member
Patron
 
Join Date: May 2015
Location: St. Louis
Posts: 63
Re: First steps towards a new adjustment tool

Did a quick & dirty test just to see if I understand the problem. I didn't use curves, and the results aren't perfect, but is this similar to the desired goal?

(The results are posterized, but I think I can take care of that.)
Attached Images
File Type: png test1.png (85.4 KB, 8 views)
File Type: png test2.png (46.0 KB, 7 views)
File Type: png test3.png (22.4 KB, 7 views)
Reply With Quote top
  #20  
Old 06-25-2015, 08:39 PM
Doug Nelson's Avatar
Doug Nelson Doug Nelson is offline
Janitor
 
Join Date: Aug 2001
Posts: 7,068
Blog Entries: 21
Re: First steps towards a new adjustment tool

It's a step, but hue tools already exist. Can it remap luminosity, or just color?
Reply With Quote top
Reply

  RetouchPRO > Tools > Software


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
RetouchPRO LIVE 3/10/2015 Learning the Pen Tool Doug Nelson RetouchPRO LIVE 8 03-14-2015 03:12 PM
Wrapping label around bottle using 3D tool. CS5 nebulaoperator Photo Compositing 7 11-11-2012 11:25 AM
Anybody sells calibrating tool for NEC PA241W? nebulaoperator Classifieds 0 07-23-2012 09:46 AM
quick selection tool when used is feathered Jerryb Photoshop Help 6 12-24-2011 04:50 AM
Drop Black tool dpnew Hidden Power Support 7 02-21-2004 11:22 AM


All times are GMT -6. The time now is 11:19 AM.


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