ArtRage applies lighting across the canvas. The top left is generally slightly lighter than the bottom right of the canvas surface. It makes it look a bit more real that a simple flat colour.
No colours in ArtRage will exactly match the colours you choose. When we were designing ArtRage and working out the lighting model, we wanted something that 'felt good' rather than was exactly numerically accurate.
This does mean ArtRage is not suitable for many uses that require exact colour-matching.
Even the default paper isn't exactly white - it has a slight yellowish tinge. This more closely matches the feel of a canvas lit with warm lights.
Additionally, most of the canvas textures in ArtRage have a slightly roughened surface, and when the light is applied it can vary the colour very slightly in small local areas to give the texture of the paper.
AndyRage's mantra for graphics engine code:
"Sure - how hard can it be?"