If I have a picture where the horizon is nearly, but not perfectly horizontal, I want to straighten it. If I rotate the image by a very small angle, the image loses sharpness slightly yet noticeably. This is understandable as it has to re-render the sloping pixels in a horizontal grid again. (16mp image) Question 1: Am I being too fussy? Or does this annoy you? It occurred to me today to use the "shear" function to level the horizon. "Transform - Shear" in the Gimp for example. This shifts blocks of pixels up and down, levelling the horizon. Yet not needing to re-render inside the blocks. Question 2: Does anyone else use this technique? It this well known? Or is this unnecessary or not effective. Am I chasing rainbows?