Problem when resizing round objects

Question

Hello,
I encounter a problem with scaling down round objects.
Here's the issue in a nutshell:
As you see when I scale down a cirle from size A to size B, the top and left sides of the circle B are flat.
Why does this happen and how to avoid it? It is really frustraiting when working with small objects.
Cheers.

Answer 1

Howdy.
The flat spots on the small circles is caused by anti-aliasing an improper alignment with the pixel grid when the circle is resized. You will see it most often when resizing a shape with an odd number of pixels. You an see below that the center of the circle is forced off the pixel grid, and the anti-aliasing is off.
Here it is actual size.
What to do?
Before you accept the transformation, move the circle until center point of the circle is on the pixel grid. Use the arrow key to move it around. Experiment. Move the center of the circle to different off grid locations before accepting the transform. You  will see all sorts of anti-aliasing permutations. Choose one that's  symmetric.The center point should be on the grid. Then the anti-aliasing should be symmetric. When the transformation is  applied, the anti-aliasing is baked in, and you can move the circle back to its original position if you need to.
As Paulo and Noel have noted, the quality of the anti-aliasing of the original circle will become apparent when it is downsized to web icon size. Any asymmetry in the original may not be noticable at normal size, as it will only involve one or two rows of pixels at the perimeter of the circle. A small percentage of assymetry on a 300px circle. When the circle is downsized to 10 pixels, the asymmetry still affects one or two rows of pixels. And the circle goes pear shaped  because the assymmetry could be as much as 10%. My guess is that the OP is working with some images that are a little out of whack to start with.
There's a lot more to this, but this might help.
Peace,
Lee