Java class to do a Gaussian or Box blur on a PNG image WITHOUT using java.awt

I need a utility class, written in Java that can take a PNG image and blur it. Any solution must ONLY use classes that are in the Google App Engine JRE white list (found here: [login to view URL]). This utility class should take 2 parameters--a PNG in the form of an array of bytes (byte []), a [login to view URL], or a [login to view URL] ([login to view URL]), and a radius used for blurring. I would like this to be a fast (performant) class so maybe doing 2 x 1D convolutions instead of 1 x 2D convolution makes sense.