Charting Image Artifacts in Digital Image Sequences Using Velocital Information Content Gregory J. Powera, Mohammad A. Karim, and Farid Ahme& aAjr Force Research Laboratory, AFRL/SNAT/Target Recognition Branch, 2010 5th Street, Wright-Patterson AFB, Ohio 45433-7001 bUniversity of Dayton, Department of Electrical and Computer Engineering, 300 College Park, Dayton, Ohio 45469-0226 cElectrical Engineering, School of Engineering and Engineering Technology, Pennsylvania State University, The Behrend College, Erie, PA, 16563-1701 ABSTRACT This paper introduces a metric called Velocital Information Content (VIC) which is used to chart quality variations in digital image sequences. Both spatially-based and temporally-based artifacts are charted using this single metric. VIC is based on the velocital information in each image. A mathematical formulation for VIC is shown along with its relation to the spatial and temporal information content. Some strengths and weaknesses of the VIC formulation are discussed. VIC is tested on some standard image sequences with various spatio-temporal attributes. VIC is also tested on a standard image sequence with various degrees of blurring using a linear blurring algorithm. Additionally, VIC is tested using standard sequences that have been processed through a digital transmission algorithm. The transmission algorithm is based on the discrete cosine transform (DCT), and thus introduces many of the known digital artifacts such as blocking. Finally, the ability of VIC to chart image artifacts is compared to a few other traditional quality metrics. VIC offers a different role from traditional transmission-based quality metrics which require two images: the original input image and degraded output image to calculate the quality metric. VIC can detect artifacts from a single image sequence by charting variations from the norm. Therefore, VIC offers a metric for judging the quality of the image frames prior to transmission, without a transmission system or without any knowledge of the higher quality image input. The differences between VIC and transmission-oriented quality metrics, can provide a different role for VIC in analysis and image sequence processing. Keywords: Image Quality, Spatial-Temporal Analysis, Digital Transmission, Image Sequence, Quality Metric, Velocital 1. INTRODUCTION Digital is currently marketed to the consumer as higher quality. However, digital image sequences still incur image quality degradation from analog sources and digital sources.1 The analog sources are predominantly from the environment such as atmospherics and from early analog stages of the digital camera such as lens focus. The digital camera and digital transmission systems have eliminated many of the quality degradation problems associated with old analog systems but at the same time, digital image sequences have introduced new image quality problems due to quantization, compression, and transmission.1 The impact of image artifacts can be charted in a sequence using a metric called velocital information content (VIC). The metric is introduced here along with examples of using it on imagery suffering from blur, quantization, compression artifacts, and spurious noise. Other author information: (Send correspondence to G.J.Power) G .J .Power: E-mail: powergj©sensors.wpafb.af.mil M .A.Karim: E-mail: mkarim©engr.udayton.edu F.Ahmed: E-mail: fxa9©psu.edu Part of the SPIE Conference on Applications of Digital Image Processing XXI . San Diego. California • July 1998 SPIE Vol. 3460 • 0277-786X/98/$1O.OO 642