Examples of uncompressed and compressed Dopplergrams. Top left: uncompressed data, top right: quantization (two velocity bins), bottom left: JPEG compression (quality = 5), bottom right: 2 × 2 subsampling combined with JPEG compression with a quality of 10. The artifacts resulting from the compression are clearly visible in the Dopplergrams. Quantization causes sharp edges in the image; if n = 2, only upflows and downflows can be separated. JPEG compression leads to blocks in the image with a size of 8 × 8 pixels, corresponding to 2.78 Mm or 5.56 Mm, if 2 × 2 subsampling is used. The images shown represent only a small part of the full size of the Dopplergrams (178 × 178 Mm).