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μSAP705100-B03, μSAP70732-B03 USER'S MANUAL
Elements V1 through Vm are 0 through 0xB in the Huffman table for the DC component. Generally,
the bit lengths of categories 2 and 1 are most widely distributed when an image is compressed. The
closer to category 11, the lower the rate of appearance of the bit length. Depending on the image,
bit lengths of categories 8, 9, 10, and 11 may not appear at all. In this case, the image is compressed
and expanded normally even when a Huffman table from which the portions for category 8 or above
are eliminated for V1 through Vm is used. If, however, an image in which the value of category 9
emerges is compressed by using a Huffman table that does not contain category 8 or above, the
compression routines of the AP705100-B03 and AP70732-B03 embed 0, of 0 bits in length, into the
compressed codes equivalent to category 9, and is normally terminated, interpreting that compressed
codes are embedded even though no compressed codes are actually embedded. If a JPEG file
created in this way is expanded, the position at which data of category 9 must appear and those that
follow either cause an error or produce an image with a mosaic-like appearance.
AC coefficients have the same tendency as DC coefficients. For example, elements V1 through Vm
are as follows in the Huffman table (jpeg_DHT_AC_Y) for the AC component supplied with the
AP705100-B03 and AP70732-B03.
0x01, 0x02, 0x03, 0x00, 0x04, 0x11, 0x05, 0x12
0x21, 0x31, 0x41, 0x06, 0x13, 0x51, 0x61, 0x07
0x22, 0x71, 0x14, 0x32, 0x81, 0x91, 0xA1, 0x08
0x23, 0x42, 0xB1, 0xC1, 0x15, 0x52, 0xD1, 0xF0
0x24, 0x33, 0x62, 0x72, 0x82, 0x09, 0x0A, 0x16
0x17, 0x18, 0x19, 0x1A, 0x25, 0x26, 0x27, 0x28
0x29, 0x2A, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39
0x3A, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49
0x4A, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59
0x5A, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69
0x6A, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79
0x7A, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89
0x8A, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98
0x99, 0x9A, 0xA2, 0xA3, 0xA4, 0xA5, 0xA6, 0xA7
0xA8, 0xA9, 0xAA, 0xB2, 0xB3, 0xB4, 0xB5, 0xB6
0xB7, 0xB8, 0xB9, 0xBA, 0xC2, 0xC3, 0xC4, 0xC5
0xC6, 0xC7, 0xC8, 0xC9, 0xCA, 0xD2, 0xD3, 0xD4
0xD5, 0xD6, 0xD7, 0xD8, 0xD9, 0xDA, 0xE1, 0xE2
0xE3, 0xE4, 0xE5, 0xE6, 0xE7, 0xE8, 0xE9, 0xEA
0xF1, 0xF2, 0xF3, 0xF4, 0xF5, 0xF6, 0xF7, 0xF8
0xF9, 0xFA