I have align to pixels turned on for new objects, but an image I placed earlier is not aligned to pixels, though it's exactly 1440 x 900. How do I set Illustrator so that when I move this image object, it will always snap to a round number?
Transform window, make sure
Align to Pixel Grid is checked. This will force things to snap.
EDIT Make sure you have a shape selected for the checkbox to work.
If that still doesn't work, go to the
Transform menu and check
Align New Objects to Pixel Grid and replace your image.
Also as AdamSchuld mentioned, you can set this setting when creating a new document under the
You need to have pixel preview on for it to work. To enable that, just go to View \ Pixel Preview on the top menu. That is what actually enables the snap to pixel mode in illustrator, which cannot be done any other way.
Checking align to pixel grid is not a good option, unless we are talking about elements made of square angle (90 degrees) lines, like rectangles and (you guessed it) 90 degree lines. When align to pixel grid is checked, every node in your object will try to align to the nearest pixel, which is not really a good idea, because you are going to have node quantization (it will look like bad pixel interpolation).