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Immary

Jagged lines at certain angles

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I drew a geometrical shape with the Pen Tool in Polygon mode.  At certain angles, the lines became jagged. Is this a bug or something else?  In the example below, the object at furthest left has the most jagged lines. But furthest right, the lines are relatively smooth.  If this is not a bug, how can I smooth the jagged edges? I'm using AD Beta now.

Rendering .tiff

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Hi Immary,

This is not a bug. Antialiasing usually works/looks better on angles near the 45ª (see attached screenshot).

Vertical and horizontal lines also look great because they fit the pixel grid assuming they are pixel aligned (no antialiasing needed).

 

post-59-0-44125800-1459441894_thumb.png

 

For complicated cases you may want to try adjusting the Coverage Map a little. Go to the Layers panel and click the cog icon to open the Blend Options dialog. Click on the Coverage Map button to adjust the graph. You may want to change to Pixel View mode to help visualising the adjustment (menu View ▸ View Mode ▸ Pixels) when zoomed in.

 

post-59-0-24309800-1459441950_thumb.png

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Thanks so much MEB! An informative and helpful reply! Is antialiasing a raster effect? Trying to keep my images vector at the moment.     

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Thanks A_B_C.  I've actually read that article before I posted my question.  But because it's a bit too technical for me (I'm not trained in this field), I just had to ask to be sure.  I think the blending will cause the image to have raster effects, but I need to be sure.  So I hope someone can answer with a simple yes or no.  :)

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Well, it is not an effect, but a basic requirement of vector information display.

Basically, the vector information of your drawing must be rasterised, if it is to be displayed on an output device like a screen or a printer. That means, it has to be represented by the elements of a raster grid. Call them pixels. Now imagine you have a path that runs diagonally through the raster grid. Then the algorithm has to decide which pixels have to be turned black on rasterisation. For example, the algorithm could turn black every pixel which is “touched” or “crossed” by the path. But that would result in a very jagged image. So the algorithm is programmed to use a more refined method for assigning colour values to pixels on the basis of the given vector information, and that results in what you are seeing. Have a look at my rough sketch below.

By using the Coverage Map button MEB was talking about, you are in fact adjusting the way the algorithm interprets your vector information during the rasterisation process for your object.

Hope that makes sense …  :)

Alex

post-1198-0-70540600-1459497441_thumb.png

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