The JPEG still pression standard.pdf

xviii IEEE Transactions on Consumer Electronics, Vol. 38, No. 1, FEBRUARY 1992 THE JPEG STILL PRESSION STANDARD Gregory K. Wallace Multimedia Engineering Digital Equipment Corporation May nard, Massachusetts This paper is a revised version of an article by the same title and author which appeared in the April I991 issue of Communications of the ACM. Abstract For the past few years, a joint ITT committee known as JPEG (Joint Photographic Experts Group) has been working to establish the first international compression standard for continuous-tone still images, both grayscale and color. JPEG’s proposed standard aims to be generic, to support a wide variety of applications for continuous-tone images. To meet the differing needs of many applications, the JPEG standard includes two basic compression methods, each with various modes of operation. A DCT-based method is specified for “lossy” compression, and a predictive method for “lossless” compression. JPEG features a simple lossy technique known as the Baseline method, a subset of the other DCT-based modes of operation. The Baseline method has been by far the most widely implemented JPEG method to date, and is sufficient in its own right for a large number of applications. This article provides an overview of the JPEG standard, and focuses in detail on the Baseline method. 1 Introduction Advances over the past decade in many aspects of digital technology - especially devices for image acquisition, data storage, and bitmapped ptlnting and display - have brought about many applications of digital imaging. However, these applications tend to be specialized due to their relatively high cost. With the possible exception of facsimile, digital images are not commonplace in general-purpose computing s