  Nowadays, the digital world is most focused on storage space and speed. With
the growing demand for better bandwidth utilization, efficient image data
compression techniques have emerged as an important factor for image data
transmission and storage. To date, different approaches to image compression
have been developed like the classical predictive coding, popular transform
coding and vector quantization. Several second generation coding schemes or the
segmentation based schemes are also gaining popularity. Practically efficient
compression systems based on hybrid coding which combines the advantages of
different traditional methods of image coding have also been developed over the
years. In this paper, different hybrid approaches to image compression are
discussed. Hybrid coding of images, in this context, deals with combining two
or more traditional approaches to enhance the individual methods and achieve
better-quality reconstructed images with higher compression ratio. Literature
on hybrid techniques of image coding over the past years is also reviewed. An
attempt is made to highlight the neuro-wavelet approach for enhancing coding
efficiency.
