View Full Version : Variable Typemasking in Illustrator

07-21-2010, 08:03 PM
I'm sure you've seen it a hundred times, especially on maps with lots of type. Labels and linework intersecting with each other, making the type difficult to read and the lines difficult to distinguish.

Here is a technique we developed at my office for dealing with these situations. It is an extension of a technique we used previously, that opens up a new aspect to the typemask.

First, place all the lines you want to "mask" (or block out) on one layer. If you want to keep these lines on separate layers, you will need a separate typemask for each layer, but it works pretty much the same way.

Now, copy all of your type objects onto a new layer. Lock the original type down so that you don't accidentaly modify it during this process. Any type object on this new layer will punch out the linework behind it. Select all of this type, and give it a stroke. The width of the mask will be equal to half of the stroke weight, so if you want to mask linework that is within a half a point of a type object, give the type a stroke that is 1 pt in width. I will typically use a weight between 1 and 1.5 points.

Color the type and strokes black. Group all the type together. Now move the group to the linework layer that you want to mask. Select all (all lines and the type group) and open up the Transparency Palette. In the menu that opens off that palette, select "Make Opacity Mask". Now uncheck the box that says "Clip" and your linework should me masked out.

NOW. Here's the cool part. You'll notice that the lines have been completely removed from around the type. But what if you just want to screen them back a bit - what if you want them set at 50% opacity near the type? Well it's easy! Instead of coloring the type and strokes black, just color them at 50% gray. Now when you make the mask, it will block out 50% of the opacity of the lines. If you want the lines at 30% opacity near type, just set the color to 70% gray. Super easy!
Also, if you want the mask opacity to vary throughout the image, you can do that too! Just remember, the parts of the mask that are black will block out everything below them, and the parts that are white will block out nothing, and all values in between likewise. You can even use gradients in your mask, leading to all kinds of possibilities for typemasking.

I used this technique in my "Barlovia" map to screen black lines around type back to 30% opacity.


07-22-2010, 01:17 AM
Awesome! I've long been a fan of the typemasking technique you included in your atlas tutorial, but this refinement makes it much more powerful. 5 stars and rep from me!

07-23-2010, 09:14 AM
Hi HRob, I'm a bit thick so it's hard to see what the effect is without a 'before' and 'after'....any chance we could have one please? I looked at the Barlovia map and couldn't see any text outlined in black either...

I guess the key to it all is the opacity mask ... as I use Drawplus I don't know what the equivalent is, but drawplus allows you to lower the opacity of the fill or stroke of any object by using a slider...is that what an opacity mask is? Drawplus also has the usual blend modes, one is called 'erase' which effectively acts as a layer mask making anything under it on that layer transparent. Is it that one?

:: Is this the sort of thing you mean?: The orange rectangle is on the bottom layer. The spiral is on the layer above it and the text (with the fill set to erase blend mode) on top of the spiral.

:: Edit...that's odd, you should be able to see the orange of the square through the text that's over it (you can in the program) but the exported jpeg knocks out the orange as well....time to write to serif! I've done a screenshot of what the type mask looks like on screen before export.

07-23-2010, 09:49 AM
If you look at the map and find a place where the text overlaps and existing map line, you'll see that the type doesn't run into the line, the line is effectively stopped short of the text, making the text more legible.
I'll gra b a ss in a second

You see where Munsall overlaps and where The Gates overlap the line.. the masking takes over there masking out the line below.

PS thanks for this awesome tip, it's a great thing to keep in the ole toolbox.

07-23-2010, 10:06 AM
Ahhhh I see, thanks Devin! Wow, serif is actually ahead of Illustrator here (apart from the bug on export). In Serif all you have to do is set the blend mode of the stroke to 'erase' and then increase the stroke size to whatever you want, everything under the stroke in the same layer is knocked out. I've had to take a screenshot of it. Hopefully the folks at serif will put the export bug right soon, they're usually pretty good that way.

It never occured to me to do this to make type more legible. Thanks for the tip, HRob and Devin! What is ubercool about it is that the type and the mask remain vector and are not rasterised.

:: edit :: what is also cool is that you can adjust the opacity of the erase blend mode by using a slider and get a partial knockout as HRob mentioned.