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首页> 外文期刊>Optical engineering >Visual acuity, contrast sensitivity, and range performance with compressed motion video
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Visual acuity, contrast sensitivity, and range performance with compressed motion video

机译：压缩运动视频的视敏度，对比度灵敏度和测距性能

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摘要

Video of visual acuity (VA) and contrast sensitivity (CS) test charts in a complex background was recorded using a CCD color camera mounted on a computer-controlled tripod and was fed into real-time MPEG-2 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, observers judged the orientation of the triangles in order to determine VA and CS thresholds at the 75% correct level. Three camera velocities (0,1.0, and 2.0 deg/s, or 0, 4.1, and 8.1 pixels/frame) and four compression rates (no compression, 4 Mb/s, 2 Mb/s, and 1 Mb/s) were used. 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 measured thresholds were fed into the TOD target acquisition model to predict the effect of motion and compression on acquisition ranges for tactical military vehicles. The effect of compression on static performance is limited but strong with motion video. The data suggest that with the MPEG2 algorithm, the emphasis is on the preservation of image detail at the COSt Of contrast lOSS.
机译：使用安装在计算机控制的三脚架上的CCD彩色摄像机记录了复杂背景下的视力（VA）和对比灵敏度（CS）测试图的视频，并将其输入到实时MPEG-2压缩/解压设备中。测试图基于三角形方向辨别（TOD）测试方法，并包含在四个可能方向上具有不同大小和对比度的三角形测试图案。在感知实验中，观察者判断三角形的方向，以便将VA和CS阈值确定为75％的正确水平。三个摄像机速度（0、1.0和2.0度/秒，或0、4.1和8.1像素/帧）和四个压缩率（无压缩，4 Mb / s，2 Mb / s和1 Mb / s）为用过的。 VA被证明对运动和压缩的任何组合都非常强大。但是，将运动与高压缩比结合使用时，CS会大大降低。测得的阈值被输入到TOD目标获取模型中，以预测运动和压缩对战术军车获取范围的影响。压缩对静态性能的影响是有限的，但对于动态视频却很强。数据表明，使用MPEG2算法时，重点在于保留对比度lOSS的图像细节。

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