Color Mixing with Subtractive/Additive Channel

  • So I've tried this a few diffrent ways but so far have been either unsuccessful or at least partially successful.

    I'm building a profile for Mbox, everything is working as I would like except for the Additive/Subtractive Color Mixing.

    The way the color channels work by default is:

    Red Subtractive = 0 - 126, Additive = 127 - 255

    Green Subtractive = 0 - 126, Additive = 127 - 255

    Blue Subtractive = 0 - 126, Additive = 127 - 255

    So Color Mixing as we, and the desk know it are in the range of 0 - 126 where 126/127 is full color and 0/255 are absence or full addition of color.

    The below setup kind of works:

    If I switch to the Subtractive Channel Function the encoders go from 0 to 1 (physical) and 0 to 127 (int8), This works on the encoders, and in the RGB color picker provided I have touched the encoders first and I don't use any of the other color picker modes.

    If I switch to the Additive Channel Function the encoders also work going from 0 to -1 (physical) and 128 to 255 (int8). This causes the RGB controls in the color picker to go below 0% and CMY to go above 100% on the color picker RGB tab, though this is kind of expected as I'm are going below 0 in physical values. It also works nicely in Mbox.

    Where is gets weird is if I switch to the HSB Field (the one with the rainbow in the Color picker tool bar) or HSB Controls, CIE or Book It automatically takes me out of the color Function (2: or 3:) in the programmer and chooses values between 128 and 255 (in the Additive range) even though that additive range has a negative physical value. the RGB faders also take me out of the color Function in the programmer, but as long as I haven't touched another color picker page it chooses values between 0 and 1 as expected.

    I've tried inverting the DMX and Encoder values, swapping my physical values between Subtractive and Additive and each time I may get something working but break something else.

    I could just ignore the additive range, but it comes in handy, I could also avoid using the other color mixing modes but these are also helpful.

    Am I just doing this wrong or is there some way to get this type of color mixing working.

  • The color Mixing terms here are kind of loose, but it basically goes like this:

    0 = Remove Color from white

    127 = Full Color

    255 = Add Color to black

    So really the "Additive" mode here is really like a Boost, where any value that is missing the color is "boosted" to full color.

    For example here is 0 , 127 and 255 on the red channel:

    So with that to save myself a little mental grief, I made three new boost Attributes.

    Initially I tried using Logical Channels, but each time I tried I could no longer patch the fixture, I tried again this morning and found that it was because I was using them wrong.

    Here I tried adding two Logical Channels, This works except you can't set the DMX To value, So in order to make the ranges I had to also add two Channel Functions (Labeled NONE 1 and 2 for me) that include the range I don't want that channel to use. But this makes a mess of the Encoder wheels.

    If I try setting to Logical Channel RedBoost to DMX From 127 it takes that 127 value and placed in on the next channel Function (None2) so it shows DMX From: 127 DMX To: 126!?

    The above patch kind of works If I select the correct Channel Function on the encoders it work as I would expect, However as soon as I touch the color mixing I end up with the same issue, the mixing uses the whole DMX range.

    I almost feel like If I could somehow set the DMX To value without adding a Channel function this might work.

  • That was it. Just saying boost should have tipped me off!

    I changed the range of the channel to 0 - 2 and made two ChannelFunctions 0 - 1 and 1 -2 and Bingo!

    For whatever reason I had my head stuck in -1 to 1 land and that was causing all of the issues.

    Thanks so much.

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