ArtRage is not a vector program. As the strokes of paint are applied by the brush, they're mixed with the existing paint on the canvas, and the paint on the brush head. The result is cells of paint on a canvas with colour, depth, viscosity and other physical properties of the paint.
When you do a rescale of the painting, it resamples the canvas, much like resizing a bitmap image. Using the edit menu's scale option to size down, then size back up will lose quality of the painting.
The canvas zoom options in the menu bar, however, do not lose any quality of the painting as you zoom in and out.
One of the options we're considering for a future release is to 'record' a painting session - keep track of all the strokes and tools - so it can be played back later.
Regarding the tracing paper. If you've loaded a tracing paper and go to the 'Edit Tracing Image...' pane, click the 'scale' button, and select manual scale.
Now, notice to the left of the small preview of the tracing image in the tracing Image settings pane, there are two buttons. One has a cross-hair - that is for moving the tracing image around when you click and drag in the main canvas. The other is a magnifying glass. Select that, then click and drag left/right in the main canvas to scale the tracing image.
Select 'Done' to return to painting.
AndyRage's mantra for graphics engine code:
"Sure - how hard can it be?"