Color Mixer brush makes Brown with Red and Yellow

[DanH]

Maybe not a bug, since it works the same on Mac and iPad, but RYB mix mode makes brown when mixing red and yellow. Don’t know why it would intentionally be designed that way, though, so maybe a bug.

[Paul Mudditt]

17 minutes ago, DanH said:

Maybe not a bug, since it works the same on Mac and iPad, but RYB mix mode makes brown when mixing red and yellow. Don’t know why it would intentionally be designed that way, though, so maybe a bug.

The difference between additive mixing RGB and subtractive mixing RYB is explained here. 

https://thecolorsmeaning.com/what-color-red-yellow-make-mixed/ 

[walt.farrell]

12 minutes ago, Paul Mudditt said:

The difference between additive mixing RGB and subtractive mixing RYB is explained here. 

However, according to the Help:

Quote

Model—selects a different color model for use with the brush. RYB is a historical subtractive color model based on red, yellow and blue as primary colors.

That sounds like RYB should give us what we're used to, and make Orange not Brown.

[Paul Mudditt]

1 hour ago, walt.farrell said:

However, according to the Help:

That sounds like RYB should give us what we're used to, and make Orange not Brown.

Sorry Walt I did not know this was an issue, the articles on this subject always seemed obvious to me.

The help talks about mixing paint which is subtractive resulting in darker colours and impossible to make white. Labeled as RYB.

”In addition, the RGB model is an additive color model, which means that the more light we add, the brighter the color will be. On the other hand, the RYB model is a subtractive color model, which means that the more pigment we add, the darker the resulting color becomes.”

Light mixing as used in TV’s and Monitors is additive which means you can create lighter colours even white by mixing. Labeled as RGB as in RGB monitor.

So in my test case I can create orange using light mixing RGB technique of red + yellow = light orange, whereas with RYB paint mixing red + yellow = dark orange (brown)

Or am I yet again misunderstanding the original question?

[DanH]

As I see it, the article referenced—What Color Do Red and Yellow Make When Mixed? (+Chart)—supports my expectation that the RYB model would produce orange when mixing red and yellow.

In addition to all their visual examples, they say: "RYB ... is a subtractive color model ... when yellow and red pigments are mixed ... this mixture will only reflect the colors that have not been absorbed, producing orange." 

The Help statement Walt quoted seems to indicate this result should also be expected in Affinity Photo as well: "RYB is a historical subtractive color model based on red, yellow and blue as primary colors."

While it is true with the RYB model, as described in the article, "the more pigment we add, the darker the resulting color becomes," it is orange rather than brown which results from mixing red and yellow, as per the examples in the article. It also says: "In painting [i.e. RYB], mixing green and red makes brown," and Affinity Photo does do that.

The article then states "In RGB, on the other hand, the same mix [green and red] makes yellow," but this is not the case in Affinity Photo's RGB model while using the Paint Mixer Brush, which makes a brown that is leaning toward yellow. So, I'm confused on what the RYB, RGB, and CMYK models (and what's Native?) in the Paint Mixer Brush are intended to do, and when they expect users would choose one over the other. Their RYB model at least seems mostly correct in emulating paint mixing except for how red and yellow mix.