On the wall of a local restaurant there are some works of art that look enormously like original thick oil or acrylic paintings on canvas, with the canvas texture showing through.
But when I look close, I notice that the canvas texture appears in places to be impressed on top of a thick paint surface, instead of being a substrate under it. Meanwhile, in other places nearby the paint layer is obviously recessed as if it were thin, but shows no canvas texture at all.
Here are examples of all three conditions:

The pigment layer appears to be continuously mixed. Quickly scanning with a 10X loupe, I have looked for but failed to find any evidence of inkspitting or halftoning.
Like I said, I'm baffled.
Can somebody tell me what process was used to make this "painting" ?
To aid your photointerpretation skills, here is an overview showing where the light comes from. The closeup is the dress at lower right.

Many thanks for a convincing answer!
--Rik