Evaluation of JPEG and JPEG2000 compression algorithms for dermatological images.

BACKGROUND: Some image compression methods are used to reduce the disc space needed for the image to store and transmit the image efficiently. JPEG is the most frequently used algorithm of compression in medical systems. JPEG compression can be performed at various qualities. There are many other compression algorithms; among these, JPEG2000 is an appropriate candidate to be used in future. OBJECTIVE: To investigate perceived image quality of JPEG and JPEG2000 in 1 : 20, 1 : 30, 1 : 40 and 1 : 50 compression rates. METHODS: In total, photographs of 90 patients were taken in dermatology outpatient clinics. For each patient, a set which is composed of eight compressed images and one uncompressed image has been prepared. Images were shown to dermatologists on two separate 17-inch LCD monitors at the same time, with one as compressed image and the other as uncompressed image. Each dermatologist evaluated 720 image couples in total and defined whether there existed any difference between two images in terms of quality. If there was a difference, they reported the better one. Among four dermatologists, each evaluated 720 image couples in total. RESULTS: Quality rates for JPEG compressions 1 : 20, 1 : 30, 1 : 40 and 1 : 50 were 69%, 35%, 10% and 5% respectively. Quality rates for corresponding JPEG2000 compressions were 77%, 67%, 56% and 53% respectively. CONCLUSION: When JPEG and JPEG2000 algorithms were compared, it was observed that JPEG2000 algorithm was more successful than JPEG for all compression rates. However, loss of image quality is recognizable in some of images in all compression rates.

Recurrent bullous lesions associated with familial Mediterranean fever: a case report.

Familial Mediterranean fever (FMF) is an inherited, recurrent, inflammatory disease. Of its various cutaneous features, erysipelas-like erythema is the best known and most common skin lesion. We present a new case of FMF with recurrent bullous lesions. A 41-year-old woman was admitted to our clinic with tense bullae, 20 x 20 mm in diameter on the left shin. The patient had a history of fever, abdominal pain, peritonitis attacks and infertility. A lesional skin biopsy revealed subepidermal bullae and neutrophilic infiltration around dermal vessels. Direct immunofluorescence analysis was negative. Over the period of investigation, the lesion regressed spontaneously; 1 month later, a similar lesion appeared on the right wrist. Diagnosis of FMF was made according to the Tel-Hashomer criteria. Recognition of this peculiar skin lesion may lead to an earlier diagnosis of the disease.