|
Modern automated microscopic imaging techniques such as high-content screening (HCS), high-throughput
screening, 4D imaging, and multispectral imaging are capable of producing hundreds to thousands of images
per experiment. For quick retrieval, fast transmission, and storage economy, these images should be saved in
a compressed format. A considerable number of techniques based on interband and intraband redundancies of
multispectral images have been proposed in the literature for the compression of multispectral and 3D temporal
data. However, these works have been carried out mostly in the elds of remote sensing and video processing.
Compression for multispectral optical microscopy imaging, with its own set of specialized requirements, has
remained under-investigated. Digital photography{oriented 2D compression techniques like JPEG (ISO/IEC
IS 10918-1) and JPEG2000 (ISO/IEC 15444-1) are generally adopted for multispectral images which optimize
visual quality but do not necessarily preserve the integrity of scientic data, not to mention the suboptimal
performance of 2D compression techniques in compressing 3D images.
Herein we report our work on a new low bit-rate wavelet-based compression scheme for multispectral fluorescence
biological imaging. The sparsity of signicant coefficients in high-frequency subbands of multispectral
microscopic images is found to be much greater than in natural images; therefore a quad-tree concept such as
Said et al.'s SPIHT1 along with correlation of insignicant wavelet coefficients has been proposed to further
exploit redundancy at high-frequency subbands. Our work propose a 3D extension to SPIHT, incorporating a
new hierarchal inter- and intra-spectral relationship amongst the coefficients of 3D wavelet-decomposed image.
The new relationship, apart from adopting the parent-child relationship of classical SPIHT, also brought forth
the conditional "sibling" relationship by relating only the insignicant wavelet coefficients of subbands at the
same level of decomposition. The insignicant quadtrees in dierent subbands in the high-frequency subband
class are coded by a combined function to reduce redundancy. A number of experiments conducted on microscopic
multispectral images have shown promising results for the proposed method over current state-of-the-art
image-compression techniques.
|
