Extremely High-Resolution Imageries (EHRI) are high-resolution images. The International Telecommunication Union( ITU-R) has divided and specified the EHRI resolutions into several resolution variants in its recommendation BT.2042.
According to the ITU-R recommendations, all EHRI variants have an aspect ratio of 16:9 and are based on the resolution of 1,920 x 1,080, which corresponds to EHRI-0 and is used in high-definition television( HDTV). They form a multiple of this base value in the vertical and horizontal directions.
Two versions are used in Ultra-HDTV, namely EHRI-1 with a resolution of 3,840 x 2,160, which corresponds to the 4K standard, and EHRI-3 with 7,680 x 4,320, which corresponds to the 8K standard. The resolution of EHRI-1 is twice that of EHRI-0, and that of EHRI-3 is even four times that of EHRI-0. The pixel count of EHRI-1 is thus four times that of EGRI-0, and that of EHRI-3 is even 16 times that.