Thanks for the answer, Qwt's Spectrogram does use interpolation but i replaced it with a fast nearest neighbor.

However, Qt is the common ground here, which means that i have to use something that can be rendered inside a Qt window. I don't know any libraries for GPU acceleration or gaming frameworks, but i guess i can write pure CUDA to transform the 2d vector of values into something that can be used with
Qt Code: 
  1. QImage(uchar *data, int width, int height, Format format, QImageCleanupFunction cleanupFunction = Q_NULLPTR, void *cleanupInfo = Q_NULLPTR)
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and then paint the QImage into a QFrame? Is that something that's worth trying?