  We propose a new approach for image compression in digital cameras, where the
goal is to achieve better quality at a given rate by using the characteristics
of a Bayer color filter array. Most digital cameras produce color images by
using a single CCD plate, so that each pixel in an image has only one color
component and therefore an interpolation method is needed to produce a full
color image. After the image processing stage, in order to reduce the memory
requirements of the camera, a lossless or lossy compression stage often
follows. But in this scheme, before decreasing redundancy through compression,
redundancy is increased in an interpolation stage. In order to avoid increasing
the redundancy before compression, we propose algorithms for image compression
in which the order of the compression and interpolation stages is reversed. We
introduce image transform algorithms, since non interpolated images cannot be
directly compressed with general image coders. The simulation results show that
our algorithm outperforms conventional methods with various color interpolation
methods in a wide range of compression ratios. Our proposed algorithm provides
not only better quality but also lower encoding complexity because the amount
of luminance data used is only half of that in conventional methods.
