Adobe's claim on Fresco's Live Brushes

So they claim to be more realistic/accurate

At Adobe Max 2019, Adobe claims Fresco's "Live Brushes" are more accurate and realistic than any other apps out there.  This statement was made by Adobe's Chief Product Officer Scott Belsky.  We feel compelled to compare their and our watercolor simulation:

Watercolor

The above video comparing the two apps' watercolor simulations and illustrate several differences. First, we use physics to model the deformation of our virtual brush, allowing subtle variations in the strokes. Because it's a 3D virtual brush that you can wield, you can e.g. making a gradient by loading different colors along the brush tuft and tilting your brush just like in real life. Fresco uses stamp to model the watercolor brush, so the above natural brush manipulation is simply not possible. Second, we use Computational Fluid Dynamics  to model wet watercolor for really natural flow patterns. Close examination of Fresco suggests that they use expanding 'waves' to model spreading   watercolor. Such modeling often gives  artificial-looking 'turtle-back' patterns. Another important point is that our flow is global instead of being restricted to stroke vicinity like in Fresco. This keeps Fresco from being able to create large-area flow patterns - a major contribution to the charm of the watercolor medium. Lastly, you can't see subtle details in Fresco's rendering when you zoom in. In contrast, Expresii can render the artwork in much higher resolution with details. 

Adobe Fresco's watercolor simulation often result in "turtle-back" patterns

Oil Paint

We also beg to differ when they say the oil paint simulation in Fresco is more realistic.  Our Computer Graphics Researcher & Developer Dr. Nelson Chu previously worked at Microsoft. His main contribution there is the oil and pastel model found in Project Gustav, which later is productized as Fresh Paint.  His work addresses the problem of missing details in oil or pastel modelling found in many other paint apps. Look at how organic are the oil paint and pastel strokes in the following video:

And here's Fresco's oil paint:

Both shows ridges and color mixing, but which one you say is more organic or feel like real oil paint?  If you ask me, I think Project Gustav / Fresh Paint is better in capturing the details and is closer to what real paint does.

Color Mixing

Another aspect  Adobe  put effort into make digital paint more realistic is color mixing.   Many paint programs simply use RGB color space (native to digital systems) and alpha blending in their tool.  Some complain Blue and Yellow don't make Green but a muddy gray. (btw, it's arguably cyan and yellow that make green and you can get a green if you mix cyan and blue in those digital systems).

Fresco's  color blending  is  probably based on this research paper . You can easily get a nice green from blue and yellow, but that's applied on watercolor only.  Yellow and blue oil still gives muddy gray:

Adobe Fresco's color mixing. Left: oil paint. Right: watercolor.

For comparison, the app   Artrage also addressed this issue since many yeas ago:

Color mixing in Artrage. Left: 'Real color mixing' OFF. Right: ON.

Real color mixing (by ChrisH407)

Perceptually I find the green in Artrage a bit artificially too bright (but hey, those blue and yellow are artificially  pure to begin with). So here I prefer the result from Adobe. However, in real world we often get a even darker green, like in the excerpt pic on the right (click to see the video on youtube).  Only cyan+yellow would make such a bright green.  Real paint chemicals also blend in a more complex way to give non-linear behavior and thus the difference.  But if you ask me, I'm okay to use simple RGB or CMY model native to computer, treating 'computer' as just another brand of paint.

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Conclusion

I would say Fresco is definitely not the most realistic or accurate when it comes to simulating watercolor and oil all in all. Their color mixing is nice and that's the only part you can possibly call it more realistic, if we consider it's blue + yellow (RYB model) instead of cyan+yellow (CMY model) giving green.  

Please leave your comments below to let us know what you think.