About FocalPaint

FocalPaint is a digital painting app for iPad that focuses on traditional painting aesthetics and workflow. It is free with an optional in-app subscription to enable extra features and updates. Subscribe to support development and enhancements, and to get new brushes and canvases.

What makes FocalPaint special?

FocalPaint doesn't use the traditional RGB or CMYK color models that most apps use. These models were designed for efficiency with little attempt to mimic real paints and media. FocalPaint pulls out all the stops and uses a 256 bits-per-pixel spectral model with 12 wavelengths representing the reflectance curves of natural pigments. These reflectance curves are blended using a weighted geometric mean algorithm to closely match the behavior of real paints and pigments. This is how blue and yellow create green in a realistic manner.  Other programs might try to use HSV or other three-channel color models but the result is rarely convincing.

Here's a brief out-of-the-box comparisons with oil brushes:


Not FocalPaint

Not FocalPaint

Also not FocalPaint

Not too bad, but not FocalPaint

What's so bad about RGB?

It's not that the R, G, and B colors are bad, but there are only three!  The real world is a continuous spectrum of infinite colors, so the more we can get the better.  Then we can mix them together to get these lovely curved mixing lines.  This is how blue and yellow can make green; a straight line would always create white or grey!

How does the 3D texture model work?

In additional to all the color information, each pixel stores thickness information, and material properties like how shiny or diffuse the paint is. This data forms a topological height-map, which is analyzed for slope information and processed with the Oren-Nayer lighting model. All of this is done in real-time thanks to the power of the iPad GPU and Metal Shading Language.

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