test pattern
noun [ C ] US uk/ˈtest ˌpæt.ən/ us/ˈtest ˌpæt̬.ɚn/ (UK test card)
测试图案（电视台播放的图片或图案，用于检测或改进图像质量）
a picture or pattern that is broadcast so that the quality of the television picture received can be examined and improved if necessary by using the controls on the equipment