Image Compression via DCT.
Ali Manan (mohammadalimanan+github@gmail.com)
Francesco Porto (francescoporto97+github@gmail.com)
Francesco Stranieri (frenkowski+github@gmail.com)
The DCT is a Fourier-related transform, that expresses a finite se- quence of values in terms of a sum of cosine functions oscillating at dif- ferent frequencies. It is vastly used in the image processing field, mostly for compression related tasks, such as in JPEG, a lossy format. Lossy compression permits reconstruction of an approximation of the original data, but reduces file size when compared to lossless formats, such as BMP (bitmap).
In this report we discuss our implementation of the Discrete Cosine Transform (DCT) in one and two dimension, called DCT1 and DCT2 respectively. We then compare our implementations in terms of execution time to the ones provided by Scipy, an open-source Python library. Finally, we present our GUI that compresses a greyscale bitmap image via a DCT2-based algorithm, while also providing a side-by-side comparison with the original image.