If you export an image, you could encounter one of the following problems with the image:
- The edges are blurred.
- A white line appears on the edges.
- The edges are not sharp and appear blurred.
- The image dimensions are not the same as when in Xtreme.
These are all caused because it's all too easy to draw shapes that cover half pixels and, because bitmap needs to include the whole drawing, the export will typically be one pixel larger than the object dimensions shown.
The best ways to avoid these problems is:
- Make sure the object, usually a rectangle, is exact pixel X,Y and width and height (i.e. 5 not 5.5).
- If you have a rectangle you're exporting, it's usually better to have no outline.
It's also worth noting the anti-aliasing options in the Bitmap Size tab of the Export dialog. Usually it's best to select Minimize Visible Anti-aliasing (which means it shifts objects very slightly to try and reduce the half pixel problem), but sometimes if you want the exact thing you see on screen, exact to fractions of a pixel (e.g. you have some very small text) it's sometime worth trying the Maintain Screen Anti-Aliasing option.
Hints for making exact pixel rectangles
In the Selector Tool:
- Set the X and Y values to whole pixel numbers, not fractional parts.
- Click the bottom left corner part of the Set Origin 9-way origin control.
- Switch off the small Lock Aspect Ratio little padlock button.
- Then you can enter an exact width and height as whole pixels, and press Enter/Return.
The reason for setting the origin to the bottom left corner is to prevent the object moving when you alter the width or height. Usually it scales things around the center point and so moves the X and Y value. And the reason for switching off the aspect-lock button is to prevent one value changing the other.
If you do that, your rectangle XY and width & height should be whole pixels and your exported size should be exactly the same. pixel size, with no anti-aliasing 'white edge' effects.
Robert Turner
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