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:
|Also not FocalPaint|
|Not too bad, but not FocalPaint|
What's so bad about RGB?
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.