Sagaen Studio has a large workspace plus a right-hand sidebar of controls (brush/eraser, undo/redo, brush size, zoom, image opacity, color picker) and a comprehensive set of image filters (brightness, contrast, hue, saturation, blur) that can be applied either to the whole canvas or

only to an imported image.

The app supports image import, draws the image centered/scaled according to a zoom factor, and lets the user paint directly on top of it using mouse or touch events.