Quote:...Where on the background layer, a 1 pixel brush is the size of 1 pixel, but the 1 pixel brush on the upper layer takes up like 16 actual pixels...
and
I wish to use the photo as a background layer and I set the drawing layer's opacity to 50% so that I can use the background for reference. Since I am drawing pixel art, I need the background to have different PPI than the layer I am draawing on.
FWIW (If I understand above) It is not possible to have an image where 16 pixel brush (4x4) on the top layer appears as one pixel underneath.
...but this is pixel art. It should not matter providing you are using the pencil tool.
...however If you scale your picture up 400%, do your overlay with the pencil tool, then scale back down to 25% using interpolation NONE to keep the pixel art I think that is the same outcome.
Edit: ..or is it the other way round ? Want a smaller pixel art version of the house ?
? Draw the overlay and scale to 25% with interpolation NONE.