On 3/1/22 14:00, Gary Aitken wrote: > On 3/1/22 8:59 AM, Gary Aitken wrote: >> I have a simple image with one straight line of a single color. >> Using the gutenprint dialog, I can print that file. >> If I do a "reverse translation" of the raw file, there is one escp2 command >> in it to print the line, shown below with some notes: >> >> 0000006a 1b ( U 05 00 08 08 08 40 0b >> units; (page1=08), (vt1=08), (hz1=08), (base2= 40 0b = 0xb40 = 2880) >> ... >> 000000c0 1b i 12 01 02 68 01 01 00 >> Print color1, compress1, bits1, bytes2, lines2, data... >> color1 = 0x12 = 18 = light cyan >> compress1 = 1 (TIFF compression) >> bits1 (bits/pixel) = 0x2 = 2 >> bytes2 = ???? = 0x068 = 360 >> lines2 is # lines to print = 0x0001 = 1 >> data = unknown, not dumped; specifies the dot size, 2 bits each >> 00000124 0c >> FF >> >> What I don't understand is what bytes2 is counting. >> There are 100 bytes between 000000c0 and 00000124. >> What does the 360 mean? >> Do the horizontal units factor or the compression type factor into this >> in some way? > > My oversight, I see the bytes2 is a count of pixels in each line. > But the question remains: > >> How do you compute where the next command (the FF) is? > > Do you have to actually decode the tiff data?
Yes you do. It's basically a simple RLE compression scheme. Repeated bytes (up to 128) are represented as [1-N][byte] Non-repeated sequences (up to 128 bytes) are output as [N][sequence] It is possible for the "compression" to expand the data some; there's a very hairy calculation for the worst case. _______________________________________________ gimp-user-list mailing list List address: gimp-user-list@gnome.org List membership: https://mail.gnome.org/mailman/listinfo/gimp-user-list List archives: https://mail.gnome.org/archives/gimp-user-list
