Search tips
Search criteria

Results 1-3 (3)

Clipboard (0)

Select a Filter Below

more »
Year of Publication
Document Types
1.  JPEG2000 Still Image Coding Quality 
Journal of Digital Imaging  2013;26(5):866-874.
This work demonstrates the image qualities between two popular JPEG2000 programs. Two medical image compression algorithms are both coded using JPEG2000, but they are different regarding the interface, convenience, speed of computation, and their characteristic options influenced by the encoder, quantization, tiling, etc. The differences in image quality and compression ratio are also affected by the modality and compression algorithm implementation. Do they provide the same quality? The qualities of compressed medical images from two image compression programs named Apollo and JJ2000 were evaluated extensively using objective metrics. These algorithms were applied to three medical image modalities at various compression ratios ranging from 10:1 to 100:1. Following that, the quality of the reconstructed images was evaluated using five objective metrics. The Spearman rank correlation coefficients were measured under every metric in the two programs. We found that JJ2000 and Apollo exhibited indistinguishable image quality for all images evaluated using the above five metrics (r > 0.98, p < 0.001). It can be concluded that the image quality of the JJ2000 and Apollo algorithms is statistically equivalent for medical image compression.
PMCID: PMC3782606  PMID: 23589187
Image compression; JPEG2000; Image quality
2.  A Novel Medical Image Quality Index 
Journal of Digital Imaging  2010;24(5):874-882.
A novel medical image quality index using grey relational coefficient calculation is proposed in this study. Three medical modalities, DR, CT and MRI, using 30 or 60 images with a total of 120 images used for experimentation. These images were first compressed at ten different compression ratios (10 ∼ 100) using a medical image compression algorithm named JJ2000. Following that, the quality of the reconstructed images was evaluated using the grey relational coefficient calculation. The results were shown consistent with popular objective quality metrics. The impact of different image aspects on four grey relational coefficient methods were further tested. The results showed that these grey relational coefficients have different slopes but very high consistency for various image areas. Nagai’s grey relational coefficient was chosen in this study because of higher calculation speed and sensitivity. A comparison was also made between this method and other windows-based objective metrics for various window sizes. Studies found that the grey relational coefficient results are less sensitive to window size changes. The performance of this index is better than some windows-based objective metrics and can be used as an image quality index.
PMCID: PMC3180531  PMID: 21104000
Image compression; Image quality analysis; JPEG2000
3.  Two non-homologous brain diseases-related genes, SERPINI1 and PDCD10, are tightly linked by an asymmetric bidirectional promoter in an evolutionarily conserved manner 
Despite of the fact that mammalian genomes are far more spacious than prokaryotic genomes, recent nucleotide sequencing data have revealed that many mammalian genes are arranged in a head-to-head orientation and separated by a small intergenic sequence. Extensive studies on some of these neighboring genes, in particular homologous gene pairs, have shown that these genes are often co-expressed in a symmetric manner and regulated by a shared promoter region. Here we report the identification of two non-homologous brain disease-related genes, with one coding for a serine protease inhibitor (SERPINI1) and the other for a programmed cell death-related gene (PDCD10), being tightly linked together by an asymmetric bidirectional promoter in an evolutionarily conserved fashion. This asymmetric bidirectional promoter, in cooperation with some cis-acting elements, is responsible for the co-regulation of the gene expression pattern as well as the tissue specificity of SERPINI1 and PDCD10.
While SERPINI1 is predominantly expressed in normal brain and down-regulated in brain tumors, PDCD10 is ubiquitously expressed in all normal tissues but its gene transcription becomes aberrant in different types of cancers. By measuring the luciferase activity in various cell lysates, their 851-bp intergenic sequence was shown to be capable of driving the reporter gene expression in either direction. A 175-bp fragment from nt 1 to 175 in the vicinity of PDCD10 was further determined to function as a minimal bidirectional promoter. A critical regulatory fragment, from nt 176-473 outside the minimal promoter in the intergenic region, was identified to contain a strong repressive element for SERPINI1 and an enhancer for PDCD10. These cis-acting elements may exist to help coordinate the expression and regulation of the two flanking genes.
For all non-homologous genes that have been described to be closely adjacent in the mammalian genomes, the intergenic region of the head-to-head PDCD10-SERPINI1 gene pair provides an interesting and informative example of a complex regulatory system that governs the expression of both genes not only through an asymmetric bidirectional promoter, but also through fine-tuned regulations with some cis-acting elements.
PMCID: PMC1796892  PMID: 17212813

Results 1-3 (3)