When I export Illustrator artwork as a png file, I get a one pixel grey border at the top and left edges.
There is no background object, but I export (Save for Web and Devices) with matte white background and no transparency. I also tried with a white background object, with it snapped to the artboard and also larger than the artboard by 10 pixels in each direction. I still got the lines at the top and left of the exported image.
I also tried making a new file, with the artboard in pixel units, and selected the option to have objects snap to pixel grid, and then copying and pasting the artwork from the original file. I still got the lines.
After much tearing of hair the following works for me:
- Select View > Pixel Preview.
- View > Snap to Pixel should be ticked.
- You should use Artboards
- The Artboards should be laid out by Illustrator not by you, so if you’ve created, copied or positioned any: Objects > Artboards > Rearrange and choose a whole pixel value for spacing. This will lay the artboards out to exact pixels.
- Choose View > Pixel Preview and check the edges of the artwork for unwanted anti-aliasing. It sometimes helps to extend shapes beyond the edges of the artboard.
- When you’re happy with how it looks, choose File > Export and tick Use Artboards
- Antialiasing type selection seems to have little effect on this issue but will effect the way your artwork looks.