June 06, 2009

You can stop asking for an “Add” mode in Photoshop

…because it’s already in there: “Linear Dodge (Add).” Seriously. Please tell a video-editing/compositing friend. :-)
I’m not entirely sure about the naming history–that is, why Photoshop doesn’t just call Add “Add.” I think it has something to do with the fact that Calculations in PS already has “Add” and “Subtract” functions, and at the time the blending mode was introduced, the team didn’t want to cause confusion with Calculations.
Of course, confusion has ensued regardless, so maybe it’s time to simply switch the blending mode name to be “Add (Linear Dodge).” Just know that if we do that and people still ask for Add, my head may literally explode.

Posted by John Nack at 10:30 AM on June 06, 2009


  • Joe Lencioni — 9:57 AM on June 06, 2009

    [Eww–but yes, like that. (I was afraid you were going to dig up some demonstration of how I’d overlooked some edge case WRT blending.) –J.]

  • Doug Nelson — 11:10 AM on June 06, 2009

    How about giving us a blending mode toolkit? All it would really need to be is two editable gradient bars (one above the other, representing the two layers) with a graphical blend editor between them. The graphical editor would match the length of the gradient bars, and let you draw in the interaction (above the middle line = more, below = less).
    Add a couple of global option buttons (color only, tone only, both, etc.) and a Load button to load in a text file with blend tables (I guess we’d need a save button for this, as well).

  • Doug Nelson — 11:42 AM on June 06, 2009

    I guess while I’m fantasizing, how about just turning the blend mode dropdown into a blending panel, with my above suggestions alongside the standard choices. And add radius and amount sliders so we could blend just edges, or everything but edges, etc.
    And have the whole thing save and display user-definable presets.
    We just did a live broadcast beauty retouch where the retoucher demonstrated using an overlay layer to burn/dodge a zillion tiny little skin imperfections. He said it would typically take him 1-3 hours for a magazine cover headshot. I’m thinking a blend panel like I described could do this with a single preset and some slider twiddling.

  • Adolfo Rozenfeld — 9:38 PM on June 08, 2009

    “Just know that if we do that and people still ask for Add, my head may literally explode.”
    If you do that, people will ask where is linear dodge!
    [Ah, but what if we simply inverted the string, making it “Add (Linear Dodge)”? –J.]

  • Bill Dahlinger — 1:57 PM on June 09, 2009

    With all due respect, there is a massive difference between Add and Linear Dodge. This has caused incongruencies across the Adobe line of products including Photoshop, Flash, and After Effects. I have to go to great pains at time to comp something up in After Effects, just so I can get the effect correct for something I want to comp for approval that will be developed in Flash. I created a simple example here: http://www.lbox.com/images/ps/linear-dodge-vs-add-example.png OR click on my name. I had to create the ADD example in After Effects.

  • Bill Dahlinger — 9:06 PM on June 09, 2009

    Reading this back, I realized that I might have left out some details or wasn’t clear. You can achieve an Additive overlay in Photoshop that matches Flash or AE if you use the Fill property and not the Opacity property. Unlike After Effects or Flash that uses just Opacity. This is what causes the problems between applications and the confusion amongst users.

  • Chris Cox — 9:11 PM on June 09, 2009

    With all due respect, the code for Linear Dodge is “result = Pin(bottom + top);” (ignoring transparency, and in 32 bit there is no pin)
    After Effects has an obsolete Add mode that they renamed because it failed to handle transparency correctly – could you be using that by mistake?
    And Flash has their own special blend modes because they want to work premultiplied.
    Are you sure you didn’t do any colorspace conversion or demultiplication due to file formats along the way?
    Linear Dodge really is Add — there’s no question about that. The math is very easy to verify.

  • Bill Dahlinger — 3:35 PM on June 10, 2009

    Thanks Chris, I appreciate the explanation of what kind of math operations are going on in each application. Maybe I can appeal to the usability and cross-application teams instead. The bottom line is, the experience is not the same between applications and this is what is causing problems and confusions amongst users more than naming semantics. Maybe it should be called Linear Dodge (Add – but use Fill instead of opacity) If you can fit that ;)

  • Dan Sollis — 3:12 AM on September 18, 2009

    OK, fair point. But how about putting “Classic Color Dodge” and “Classic Color Burn” back. I hated Photoshop 6 when they changed those – very useful – blending modes. The new color burn/dodge looks really muddy and grungy compared to the old version. I don’t care about the algorithms behind it and whether they’re more physically accurate in the new version. They just don’t look as good.

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