Disappearing outline segments when saving for web

[Quality_Ctrl@adobeforums.com]

Hello everyone, I have a number of Illustrator 10 files that have a box with no fill, stroked @ 1 pt., serving as an outline. When I save these as jpegs, segments of the outline, such as the top or top and right, disappear. Thanks in advance, for any help.

[Mordy_Golding@adobeforums.com]

This is due to the antialiasing that's being applied. You have several options. First, you can draw a rectangle that is of the exact size you need to export and set cropmarks. Then when you export, that will be the exact size and nothing will get "clipped". Another method requires more work but is more precise. It requires some explanation as well.

Graphics for the web are usually antialiased, to get rid of jagged edges. Illustrator,which started life before the web became popular, has traditionally only used antialiasing to preview graphics nicer on screen. In any case, Illustrator now has something called Pixel Preview mode, which displays graphics on screen as you would see it in a browser, with antialiasing. So the first step is to turn that on.

Next, Illustrator, by default, has Snap to Pixel turned on (if you're not in Pixel Preview mode it's called snap to grid). Turn this OFF. You'll see why in a minute.

Now let's talk about how Illustrator draws strokes. When you specify a 1pt. stroke, Illustrator places that line directly on the center of the path -- meaning in essence, that you have .5pt (or .5 pixels for that matter) on either side of the path.

Now let's put it all together: By default, Illustrator will snap to pixel -- meaning your objects will always start exactly on a pixel. If you specify a stroke of 1 pt, Illustrator paints that as .5 pt on either side of the path. You can't paint just half a pixel, and so antialiasing turns that 1pt black stroke into a fuzzy gray 2 pt. stroke (hence, coloring 2 full pixels instead of 2 half pixels)... You'll see this clearly if you're in Pixel Preview mode.

So now that we know about the settings mentioned above, let's apply them. Draw your object, stroke it with a 1pt stroke, make sure snap to pixel is turned off and then open your general preferences and change your keyboard increment to .5pt -- now you can "nudge" your art a half a pixel at a time -- and you'll be able to align your object so that all of your pixels are black and not fuzzy gray.

:) Mordy