Histogram Uniformization for Digital Image Encryption

In this paper, histogram uniformization of digital images by means of the finite field cosine transform (FFCT) is examined. The approach consists in dividing the image into blocks and applying the FFCT, in a recursive manner, to each block. Simulations of the procedure show that the histogram of the transformed image exhibits a uniform shape and its pixels have low correlation with their neighbors. This result is achieved due to the modular arithmetic used in the application of the FFCT to the image blocks. The suitability of the proposed technique in the context of image encryption is discussed.