Two different versions of the revised watermark have
shown promise with JPEG. One version consists of 0 and
1, and the other consists of -1 and 1 (the bipolar watermark).
Since the {0,1} watermark has greater low frequency
energy than the bipolar one, it was thought that
JPEG might destroy less of this watermark. This would
mean that the average value of δ would be less after JPEG
compression and decompression. Figure 1 shows the average
value of δ using all 6,144 blocks of the watermark
for various compression levels using both versions of the
revised watermark.