Advantage in image fidelity and additional computing time of JPEG2000 3D in comparison to JPEG2000 in compressing abdomen CT image datasets of different section thicknesses

Abstract

In compressing abdomen CT image data sets of different STs, the advantage of JPEG2000 3D over JPEG2000 increases as the ST increases from 0.67 to 2 mm, and then slowly decreases as the ST increases from 2 to 5 mm. The practical advantage of JPEG2000 3D is limited for a submillimeter ST due to its greater computing time with only a marginal improvement in image fidelity.

Introduction of heat map to fidelity assessment of compressed CT images

“…The pooled value, typically computed as the arithmetic mean of all the individual responses, has been considered to be a reasonable and practical, although not perfect, measure to summarize large complex data. [1][2][3][4][5][6][8][9][10][11] In the previous paper, 5 the authors had to plot only pooled values, because they considered it unrealistic to illustrate the entirety of such large complex data in the limited space of a conventional line graph, bar graph, or table. It should be noted that, such pooling intrinsically obscures the variations among observers or images, which may also be an important finding of an experiment in regard to the reliability in observers' subjective judgments.…”

“…5 In that experiment evaluating the advantage of Joint Photographic Experts Group 2000 (JPEG2000) 3D (part 2) compression over JPEG2000 2D (part 1) compression, 120 abdomen CT images were irreversibly compressed to six compression ratios using both compressions. Five radiologists (radiologists 1-5) independently determined the fidelity of the 720 compressed images (120 original images  6 compression ratios) for each compression on a four-point scale (grades 1-4), where a higher grade indicated higher image fidelity.…”

“…This trend supported the conclusion of the previous study: JPEG2000 3D compression yields higher quality than JPEG2000 2D compression. 5 FIG. 2.…”

“…As multiple observers can assign different fidelity scores to an image based on their subjective judgments, the observers' responses to the image have been typically pooled into a single value to provide an overall indication of the image fidelity. [1][2][3][4][5][6][8][9][10][11] However, such pooling obscures the interobserver variability, which may be important in interpreting multiple observers' response patterns.…”

The Current Role of Image Compression Standards in Medical Imaging

“…In Part 1 of the standard, component decorrelation can be performed using a reversible or an irreversible color transform, which decorrelate RGB images to luminance and chrominance components. In Part 2, any number of components can be decorrelated using arbitrary MCTs, in some cases producing improvements in compression performance [40][41][42][43] (It is important to distinguish the Parts 2 and 10 of the JPEG2000 standard: Part 2 provides an MCT stage which can be used with volumetric data sets whereas Part 10 defines a 3D extension of the standard for volumetric imaging applications. As will be discussed in Section 4, the Part 2 has its own DICOM transfer syntax [44]; However, Part 10 has not been added to DICOM).…”