Lanczos Resampling With ActionScript

It has been a while since I worked on some interesting library. But the day has come 🙂 and here it is. Let me introduce you LanczosBitmapDataResizer class. Lanczos resampling is an interpolation method used to compute new values for sampled data. In resampling (resizing) images it is considered to be one of the best algorithms at all. Lanczos is a convolution filters. That means a filter that for each output value moves the convolution functions point of origin to be centered on the output and then multiplies all the values in the input with the value of the convolution function (kernel) at that location and adds them together.

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How to resize an image with ActionScript (update)


If you need to resize an image on client side, I mean real bitmapData resize (not just showing scaled), feel free to use ImageResizer class. This class takes bitmapData of source image, new width and height and resize method (defined by ResizeMath class), and returns new bitmapData of resized image.

Update: It seems that bitmapData.draw() method uses bilinear algorithm when scaling via Matrix. Bilinear algorithm gives you fine results when downscaling no more than 2 times (400px -> 200px). So, I added bilinearIterative() method into ImageResizer class that creates resized bitmapData by multiple steps achieving much smoother results!

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