Blog: Secrets from the Chef

Rasterizing in Adobe Illustrator 10 & CS

Yegor GilyovAuthor: Yegor Gilyov
4 November 2004

Many a stumbling block is there on the way of a patient icon designer. Some you jump, some you push away but still once you stumble. The question “how to make a tiny nice picture — an icon — from a big nice picture?” is in the first lines on the top problem list. In other words, how do you make a raster icon out of a vector-based picture without the loss of clarity and sharpness of the image?

An extreme way to do so is to draw in the desired pixel size trying to match the object and pixel borders. This isn’t difficult to control using the Pixel Preview mode of Adobe Illustrator.

But what should you do if you have to make the same icon in several sizes, say in 32×32, 24×24 and 16×16? If you ask me, I start the drawing with the largest size and then shrink the picture in a vector-based editor and match the pixels while controlling it through Pixel Preview. Same thing for all sizes.

Icon in 3 sizes

Nobody told it would be any easy.

Another good thing to do is to draw a border snapping it exactly to the pixel grid (e. g. X:10,5px Y:10,5px W:500px H:500px Weight:1px). Then the picture won’t shift when being rasterized and the borders you checked in the Pixel Preview won’t get blurred.

The most observant and daintiest experimenters will notice, however, that what you have exported to a bitmapped file (e. g., PSD) is not quite the exact match to the image in the Pixel Preview.

Pixel Preview and PSD export

That’s another little yet displeasing thing. When it takes you a few hours to make that icon, it is really painful to see a result which is only close to what you’ve been trying so hard to get.

The thing is that there are two anti-aliasing algorithms in Adobe Illustrator:

  • Art Optimized for graphics without text;
  • Type Optimized for text proper.

It is absolutely beyond my understanding why the export to a bitmapped file always uses the first algorithm and why the displaying of the image in the work window uses the second. There is nothing we can do about the preview mechanism. However, there is a way to make a bitmapped file that will be the exact match to the picture in the Pixel Preview. Before exporting you should force the rasterization of all objects using the Rasterize effect and check that the anti-aliasing algorithm in the dialog box is set to Type Optimized.

Rasterize

Only then you can export your picture to PSD format, apply some Sharpen or Unsharp Mask effects to your taste and, finally, you can bow you head to the right and enjoy the result.

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