Is digital image compression acceptable within diabetic retinopathy screening?

• DOI: 10.1046/j.1464-5491.2003.01022.x
• Publication Date: 2003-08-19T16:05:43Z
• Authors: A. Basu; A. D. Kamal; W. Illahi; M. Khan; P. Stavrou; R. E. J. Ryder
• Keywords: JPEG; Digital Imaging; Lossless JPEG; Fundus Photography

Abstract Aims The National Screening Committee (NSC), whilst recommending the use of digital mydriatic retinal photography for diabetic retinopathy screening, has not yet accepted digitally compressed images grading. By greatly reducing file size, however, compression is invaluable storage and its rapid transmission across computer networks. We undertook a study to compare different levels JPEG with original bit‐mapped image determine whether there was any loss clinical detail following compression. Methods Three hundred thirty were analysed in this study. These had been captured from 66 eyes consecutively photographed screening programme, using Sony DXC‐950 P 3CCD colour video camera mounted on Canon CR6‐45NM f fundus camera. Single 45° macula‐centred taken each eye. algorithm within Adobe Photoshop (version 4.0) then displayed Trinitron monitor. Four used, JPEG‐1, JPEG‐2, JPEG‐3, JPEG‐4, an objective analysis undertaken ‘lesion counts’. assessed separately blindly results compared their BMP images. Results Eight could be evaluated (five right eye three left eye). A total 290 therefore used final evaluation. All JPEG‐1 sizes between 16 24 kb found ‘pixelated’, while JPEG‐4 (66–107 kb) appeared similar (1.3 Mb) Both JPEG‐2 JPEG‐3 significantly lower counted lesions than Conclusions From our findings we can conclude that only some degree (compression ratios 1 : 20 12) 66–107 permissible format, whereas obtained after higher may suitable screening.