The Effect of Compression on Clinical Diagnosis of Glaucoma Based on Non-analyzed Confocal Scanning Laser Ophthalmoscopy Images

Abstract

* BACKGROUND AND OBJECTIVE: To evaluate the effect of different image compression formats of non-analyzed Heidelberg Retina Tomography (HRT; Heidelberg Engineering, Heidelberg, Germany) images on the diagnosis of glaucoma by ophthalmologists. * MATERIALS AND METHODS: Thirty-three topographic and reflectance images taken with the HRT representing different levels of disease were transformed using nine different compression formats. Three independent ophthalmologists, masked as to contour line and stereometric parameters, classified the original and compressed HRT images as normal, suspected glaucoma, or glaucoma, and Kappa agreement coefficients were calculated. * RESULTS: The Tagged Image File Format had the largest file size and the Joint Photographic Experts Group (JPEG) 2000 format had the smallest size. The highest Kappa coefficient value was 1.00 for all ophthalmologists using the Tagged Image File Format. Kappa values for JPEG formats were all in the range of good to excellent agreement. Kappa values were lower for Portable Network Graphic and Graphics Interchange Format compression formats. * CONCLUSION: Image compression with JPEG 2000 at a ratio of 20:1 provided sufficient quality for glaucoma analysis in conjunction with a relatively small image size format, and may prove to be attractive for HRT telemedicine applications. Further clinical studies validating the usefulness of interpreting non-analyzed HRT images are required. [Ophthalmic Surg Lasers Imaging 2005,36:323326.1

Definition of Compression Ratio: Difference Between Two Commercial JPEG2000 Program Libraries

“…However, the difference in the definition of compression ratio and its underlying principle are common to all medical images, which are the targets of telemedicine and e-health, as long as padding bits are used to store pixel data aligned on a byte boundary. Further investigations are warranted if medical images other than radiological images, including pathologic, 39 ophthalmologic, 40 orthodontic, 41 and cardiologic images, 42 are prone to the aforementioned confusion in the definition of compression ratio. Third, we did not reveal the results of image quality.…”

Grading Diabetic Retinopathy Severity From Compressed Digital Retinal Images Compared With Uncompressed Images and Film

“…Validation and comparing images of different compression ratios [25][26][27][28][29][30][31][32] and algorithms 25,29,30 is subjective and time consuming. Quantitative metrics have been used to supplement subjective assessments associated with human observer performance.…”

Roundness variation in JPEG images affects the automated process of nuclear immunohistochemical quantification: correction with a linear regression model

“…In most published immunohistochemical studies, these images have been captured with the maximum quality in an uncompressed TIFF format. Compression of DIs has been used in several fields of medicine (Atalag et al 2004;Belair et al 2005;Gurdal et al 2001;Li et al 2001;Ohgiya et al 2003). The most widely used compressed image format is the JPEG (compressed or lossy formats).…”