ArtRage 5 Product PageArtRage Lite Product PageArtRage for iOS Product PageArtRage for Android Product PageArtRage  Android Oil Painter Free Product PageArtRage  Free Demos Page

Results 1 to 8 of 8

Thread: Saturation Blend Mode

  1. #1
    Join Date
    Nov 2011
    Posts
    937

    Saturation Blend Mode

    A common practice in digital painting is to check a painting's colour values while working by placing a layer at the top of the layer stack that is pure black (0.0.0) and setting it's blend mode to 'Saturation'.
    This layer can then be toggled On/Off as you work to check values.

    However when using this method in ArtRage this "value view" as it were of the painting appears much brighter/blown out than in other apps using this method.
    Below are two test images made this way, one using Photoshop and the other ArtRage.
    Is this a bug?

    The actual test files can be found in a .zip here: https://dl.dropboxusercontent.com/u/...ValueTests.zip

    Click image for larger version. 

Name:	PS_ValueTest.jpg 
Views:	67 
Size:	384.3 KB 
ID:	84211 Click image for larger version. 

Name:	AR4.5_ValueTest.jpg 
Views:	69 
Size:	145.7 KB 
ID:	84212
    Maker Of Replica Macoys

    Techie Stuff:
    ArtRage 5.0.5 ~ 15" Macbook Pro
    + 22" HD Monitor ~ macOS 10.12.6 ~ 4 Core i7 3.1GHz CPU ~ 16GB RAM ~ Wacom Intuos4 M and a Spyder4Pro (to keep the colours true!)

  2. #2
    Join Date
    Oct 2007
    Location
    NC, USA
    Posts
    2,874
    I've found using the "color" blend mode is a better option for this, in ArtRage. The light doesn't shift like it does with the saturation option (or as much, at least).
    Nothing is easy to the unwilling.

  3. #3
    Join Date
    Apr 2012
    Posts
    299
    See my investigation into AR blending in the Tips and Tricks section.

    It "works" the way it "works"....

  4. #4
    Join Date
    Mar 2006
    Location
    New Zealand
    Posts
    3,140
    The Saturation Blend Mode in ArtRage is doing a flat mathematical replacement of the saturation component of the HLS value of the pixels, which results in the lighter image you see. While we're not privy to the internals of Photoshop's blend modes, our guess is that they're doing a calculation based on the visual saturation of the image rather than the pure numerical saturation which results in a different resulting luminance scale. The Colour blend mode in ArtRage does that so should work as a replacement.

    We've logged it in our bug list though so we can look in to it.
    Matt
    ArtRage UI
    Ambient Design.

  5. #5
    Join Date
    Apr 2012
    Posts
    299
    Quote Originally Posted by MattRage View Post
    The Saturation Blend Mode in ArtRage is doing a flat mathematical replacement of the saturation component of the HLS value of the pixels, which results in the lighter image you see. While we're not privy to the internals of Photoshop's blend modes, our guess is that they're doing a calculation based on the visual saturation of the image rather than the pure numerical saturation which results in a different resulting luminance scale. The Colour blend mode in ArtRage does that so should work as a replacement.

    We've logged it in our bug list though so we can look in to it.
    MattRage

    When you say" flat replacement of the saturation component" (which is S) "of the HLS value", does that mean that the L value is supposed to be untouched?

    I ask because this does not seem to be the case from my tests: see the second post in this thread:

    http://forums.artrage.com/showthread...lending-Engine
    Last edited by DarkOwnt; 11-21-2014 at 10:10 AM.

  6. #6
    Join Date
    Mar 2006
    Location
    New Zealand
    Posts
    3,140
    The L value should be untouched. There's a difference between visible luminance and the L value of a pixel which is why it changes visually. This blend mode takes the S value of the layer above and replaces the S value of the corresponding pixel beneath. The L value of the pixel beneath remains the same. Photoshop does a visible luminance blend, which can vary more components (the overall luminance of some hues is higher than others for example, green has higher visible luminance than blue even if the L values of the two samples are the same).
    Matt
    ArtRage UI
    Ambient Design.

  7. #7
    Join Date
    Apr 2012
    Posts
    299
    Quote Originally Posted by MattRage View Post
    The L value should be untouched. There's a difference between visible luminance and the L value of a pixel which is why it changes visually. This blend mode takes the S value of the layer above and replaces the S value of the corresponding pixel beneath. The L value of the pixel beneath remains the same. Photoshop does a visible luminance blend, which can vary more components (the overall luminance of some hues is higher than others for example, green has higher visible luminance than blue even if the L values of the two samples are the same).
    So I should be able to confirm the L value has stayed the same using the dropper tool and a colour picker displaying in HSL mode?

    I ask because from my tests this does not seem to be the case. See the second post from my blending analysis thread:

    http://forums.artrage.com/showthread...lending-Engine
    Last edited by DarkOwnt; 11-21-2014 at 10:11 AM.

  8. #8
    Join Date
    Mar 2006
    Location
    New Zealand
    Posts
    3,140
    Sorry, I used the wrong terminology - You can't use the HSL tool for this because the result of the blend is processed via HSV rather than HSL which will create some variance in visual luminance (and the L component may change dynamically due to this). In addition, there's gamma correction applied to this to offset inaccuracies created by the small colour space available.

    We replace the saturation value in HSV space and correct for gamma.
    Matt
    ArtRage UI
    Ambient Design.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •