Compression color space estimation of JPEG images using lattice basis reduction

Given a color image that was quantized in some hidden color space (termed compression color space) during previous JPEG compression, we aim to estimate this unknown compression color space from the image. This knowledge is potentially useful for color image enhancement and JPEG re-compression. JPEG quantizes the discrete cosine transform (DCT) coefficients of each color plane independently during compression. Consequently, the DCT coefficients of such a color image conform to a lattice. We exploit this special geometry using the lattice reduction algorithm used in cryptography to estimate the compression color space. Simulations verify that the proposed algorithm yields accurate compression space estimates