Recommendations For Sending Data to the
Printer
The HP PCL 5 printers perform best in terms of speed and memory
utilization if the recommendations made below are followed. Failure
to follow these recommendations will not harm the printer, but may
increase the chances of a memory out condition or increase the time
to print a page.
• Ordered Images — Raster Graphic images or pictures should
be sent from top to bottom with the data in one band (start
raster, end raster pair). If one band is not possible, as few as
possible multiple bands may be used as long as they exactly
follow each other and are sent in top-to-bottom order. Also,
multiple bands should be as large as possible.
• Band Sizes — If an image is sent in bands (start raster, end
raster pairs), the bands should be multiples of 32 lines high.
This is especially critical for landscape graphics. If there is no
way to send multiples of 32-line high bands, multiples of four
for band height should be used. This allows Image Adapt to
work better.
ENWW
Memory Usage 5-5
• Avoid Non-Raster Commands — During the transmission of
sequential raster bands non-raster commands should be
avoided. This includes cursor positioning commands.
• Separation of Images — If more than one image or picture is
to be printed on a page, it is best to keep them separate.
Separation consists of assuring that the new image starts with
a new start raster command and that the one image does not
exactly follow the next image (separate the image by at least
one line vertically and sixteen pixels horizontally). This
constraint improves the operation of Image Adapt.
• Rectangular Images — All HP LaserJet 4 family printers
perform best if raster images are sent as rectangular images
to the printer. This entails keeping the right margin of the
image constant and keeping all lines the full image width (no
lines are truncated). Also, avoid skipping lines. When whole
blank lines appear in the image, either send zeroed data
row(s) or use the Raster Y-Offset command.
• Avoid Unnecessary Print Model Use — Print model modes,
other than source and pattern transparent, degrade memory
efficiency. (This restriction is not true for the HP Color LaserJet
printer.) For best results do not use an opaque source unless
there is an image known to already be on the page in the same
area. Following the other rules listed in this section minimizes
the impact of using non-transparent print model modes.
• Avoid Tall, Narrow Images — For ADC, images which are
taller than they are wide by more than eight to one disable the
printer's ability to automatically separate images upon the
page (this restriction is not true for the HP Color LaserJet
printer). This violation is desirable in the case where the above
rules are violated and multiple images are rendered as one
image and sent to the printer as one combined image.
Sending raster data as a checkerboard with non-full width
bands sent left to right and top to bottom also disables the
printer's automatic image separation. In general, for all
HP LaserJet printers, tall, narrow images should be avoided
since they typically require more memory.
5-6 Memory Usage
ENWW
• Wide Patterns — Patterns can use up a lot of memory—
avoid them if possible. Avoid patterns which, in their final
orientation, are not 1, 2, 4, 8, 16 or 32 (32 is for all but the 4L)
bits wide. Patterns of other sizes will be tiled out to the full
width of the page and can consume a large amount of memory
(since the HP Color LaserJet printer does not perform this
way, it is not a factor for this printer). Note that a landscape
pattern that is 16 wide by 5 high would become 5 wide by 16
high when rotated and be subjected to being tiled across the
page.
• Avoid Unnecessary Pattern Selection — In HP-GL/2, avoid
issuing redundant Fill Type (FT) and Line Type (LT)
commands. These commands may cause patterns to be
rebuilt and tiled for each invocation.
• Avoid Many Small Polygons — In HP-GL/2 avoid entering
and exiting polygon mode repeatedly as it fragments memory.
If possible send down fewer, larger polygons.
• Download Font Characters as Needed — All PCL 5 printers
operate best if fonts and outlines downloaded do not include
information for characters which are not used upon the current
page. It is also best to download bitmap characters in the
orientation which they will be used.
Note
When deleting font characters and patterns, remember that if a
pattern or font character is used on the current page, any deletion
commands affecting it will not be executed until the page is printed.
ENWW
Memory Usage 5-7