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    <p>There actually is a way to do what you're trying to do using just the ie matrix transformation filter. </p> <p>in addition to M11, M12, M21, M22, the matrix also has two additional properties: Dx and Dy for translation. Unfortunately, you can't just translate by a constant amount. In order to rotate about the center of the object, you need to compose three transformation. </p> <p>First, translate the center of the object to the origin. Second, rotate the object. Third, translate from the origin back to where the center belongs. </p> <p>IE does not have the ability to compose multiple matrices itself, so you have to do the linear algebra yourself. Suppose theta is the angle by which you want to rotate, and suppose that the object's width is 2w while its height is 2h. (So w and h are the HALF width and height respectively.) Let c and s stand for cos(theta) and sin(theta) respectively.</p> <p>The matrix product you want to compute is then:</p> <pre><code> [[1 0 w] [[c -s 0] [[1 0 -w] [0 1 h] [s c 0] [0 1 -h] [0 0 1]] [0 0 1]] [0 0 1]] </code></pre> <p>which equals:</p> <pre><code> [[ c -s (-wc + hs + w)] [ s c (-ws - hc + h)] [ 0 0 1 ]] </code></pre> <p>So, if you compute the two quantities (-wc + hs + w) and (-ws -hc + h) and add them to your filter as Dx and Dy respectively, the end result will be that the rotation is about the center of the object. </p> <p>I have coded this up and tested it for a project in which I needed to animate having an object rotate about its center, and this worked for me. </p>
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    1. POJavaScript IE rotation transform maths
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    1. COThe most amazing answer on the internet. Thank you mikepr. I know this post is an year old, but, could you please tell me how you got the initial matrix product that needs to be computed?
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    2. COThanks, Kzest. I derived the matrix product from what I recall of my linear algebra courses. The 3x3 (instead of 2x2) matrix transform allows for translation. In this system, a single point is represented as a vertical matrix [x y 1], and you transform it using a 3x3 matrix by standard matrix multiplication with the matrix on the left and the vector on the right. When composing multiple transformations, the transformations are applied from right to left. Here, the right-most matrix translates the center of the image to the origin; the middle rotates it; and the right most translates it back.
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