How to Unit Test an image processing library for the Android platform?

I am currently working in an image processing library for Android, but I wonder which way would be the best to unit test the library methods.

I know that the way images are loaded inside and outside of the device may lead to different numbers in the values of the pixels, so comparing matrices directly: previously processed开发者_如何学JAVA outside android environment, with the ones inside, doesn't seem to be a good nor reliable way to do this.

Any hints and suggestions are welcome.

Thanks in advance.

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Define an error tolerance that you're willing to accept. This may be peak absolute error, or peak relative error, or SNR, or something else. It depends on what your application is doing.