Visual Acuity and Contrast Sensitivity with compressed motion video
conference paper
Video of Visual Acuity (VA) and Contrast Sensitivity (CS) test charts in a complex background was recorded using a CCD camera mounted on a computer-controlled tripod and fed into real-time MPEG2 compression/decompression equipment. The test charts were based on the Triangle Orientation Discrimination (TOD) test method and contained triangle test patterns of different sizes and contrasts in four possible orientations. In a perception experiment, VA and CS thresholds at the 75% correct level were obtained for three camera velocities (0, 1.0 and 2.0 deg/s or 0, 4.1 and 8.1 pix/frame) and four compression rates (no compression, 4Mb/s, 2Mb/s and 1 Mb/s). VA is shown to be rather robust to any combination of motion and compression. CS however dramatically decreases when motion is combined with high compression ratios. The data suggest that with the MPEG2 algorithm the emphasis is on the preservation of image detail at the cost of contrast loss.
Keywords: sensor, image compression, performance, TOD, Acuity, Contrast Sensitivity Target Acquisition
Keywords: sensor, image compression, performance, TOD, Acuity, Contrast Sensitivity Target Acquisition
Topics
AcuityContrast sensitivity target acquisitionImage compressionPerformanceSensorTODAcuityComplex backgroundCompression ratesContrast lossContrast sensitivityContrast sensitivity target acquisitionDifferent sizesHigh compression ratioMotion videoPerception experimentPerformanceTest chartsTest methodTest PatternTODTriangle orientation discriminationsVisual acuityCamerasComputer control systemsDigital image storageImage compressionImaging systemsInfrared devicesOptoelectronic devicesSensorsThermography (imaging)VisionTestingtriangle orientation discrimination todcontrast sensitivitytarget aquisitionperformanceimage processingvisual acuity
TNO Identifier
28731
Publisher
Spie: The International Society for Optical Engineering.
Article nr.
730006
Source title
Infrared Imaging Systems: Design, Analysis, Modeling, and Testing XX
Editor(s)
Holst, G.C.
Place of publication
Bellingham, WA