Hi, here is an excerpt from the "Project primitives > Projects" chapter of the manual that I think will answer your question:
[quote:y4vr6eny]Pixel rounding
By default Construct 2 objects can be drawn at sub-pixel positions, e.g. (100.3, 200.8). If the browser is using linear filtering, this can make fine pixel art appear blurry. If Pixel rounding is set to On, Construct 2 objects round their position to a whole number before drawing, e.g. (100, 201). This prevents any blurring, and can also prevent "seams" appearing on grids of objects. Note this does not affect their actual X and Y co-ordinates, which can still be between pixels - it only affects where they are drawn on the screen.
I hope this helps.