HP PCL 5 User Manual download pdf (Page 148)

6-28 Raster Graphics EN

?*r1A – The start raster graphics command initializes the seed row

to all zeros.

Row 1 –

?*b3m2W(00000001)(11111111)

The 3m selects the delta row compression method and the 2W

indicates 2 bytes of data to follow. The first three bits of the first data

byte, the command byte, signify a single byte replacement (all three

bits are 0). The next five bits indicate an offset of 1 byte from the

current position. The replacement byte follows and contains

11111111.

Row 2 –

?*b2W(00000010)(11110000)

The first three bits of the command byte indicate that one byte will be

replaced, and the next five bits indicate a relative offset of 2, so the

replacement will occur 2 bytes from the current position. The

replacement byte follows and contains 11110000.

Row 3 –

?*b5W(00000000)(00001111)(00100010)

(10101010)(10101010)

As in the other rows, the first three bits of the command byte are zero,

indicating a single byte replacement. The five offset bytes indicate a

relative offset of zero bytes. The replacement byte follows and is

00001111. The third byte is another command byte and the first three

bits signify the replacement of two bytes (the top three bits are 001).

The offset bits indicate an offset of two bytes from the current

position. The fourth and fifth bytes are the two replacement bytes.

Adaptive Compression (Method 5)

Adaptive compression enables the combined use of any of the four

previous compression methods (0 through 3), and it includes the

ability to print empty (all zeros) rows or to duplicate rows.

Adaptive compression interprets a raster image as a block of raster

data rather than as individual rows. The result of this interpretation is

that the Transfer Raster Data (

?*b#W) command is sent only once at

the beginning of a raster data transfer, and the value field (#) identifies

the number of bytes in the block of rows. For the other compression

methods, the Transfer Raster Data command is sent at the beginning

of each row and the value field (#) identifies the number of bytes for

that row only.

Row 3 00001111 11111111 11110000 10101010 10101010

1 2 ... 143 144 145 146 147 148 149 150 151 152 153 ... 285 286

No comments

HP PCL 5 User Manual Page 148