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How the workstation, network, and printer process large and multiple graphics pages has a
significant impact not only on overall printing speed but also on output quality and the productivity of
users and workgroups. Conversion of a page into a bitmap image can be done either in the user’s
workstation or in the printer.
• When print jobs are processed in the workstation, large bitmap image files are produced that must
be sent over the network to the printer.
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In this case, the workstation and printer must be
synchronized, because delays in sending data (due to workstation or network load) can cause the
printer to stop and wait for data. This produces visible bands on the print because the ink dries
differently when the print carriage stops and waits compared to continuous printing. This effect is
called “wait-state banding”. When processing large and complex pages, and when sending
multiple bitmap image files over the network, dependable printing performance and print quality
can be compromised by workstation load and heavy network traffic.
• When print jobs are processed in the printer, the workstation sends only compact spool files
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to the
printer. This data is converted to a bitmap image in the printer so that the large volume of bitmap
data is kept within the printer’s internal high-bandwidth image processing architecture. Situations
where the printer must stop and wait for incoming data are effectively eliminated, and workstation
and network loading are significantly reduced benefiting both individual users and network clients.
By processing images in the printer, HP Designjet T1100- and T610-series printers provide
dependable printing performance and productivity benefits to single users and workgroups.
Furthermore, real image quality benefits are realized because graphical elements, such as text and
lines, are recognized by HP’s embedded language processors.
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This allows HP Designjet printers to
optimize bitmap image generation to produce crisp, clearly-readable text and sharp lines especially
when printed against colored or neutral backgrounds.
Image Processing Pipeline: T610-series
The image processing pipeline of HP Designjet T610-series printers is optimized for single-user
environments. Figure 2 shows the data paths from the printer’s I/O manager
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through to pixel
instructions sent to the printheads. Internally, 24 bits per pixel (bpp) sRGB and device-dependent
RGB paths are supported along with a 32 bpp path for device-dependent CMYK. Processes are
color-coded in the figure to show whether they are performed in software (SW) or hardware (HW).
Figure 2. Image Processing Pipeline: HP Designjet T610-series Printers
Image processing in HP Designjet T610-series printers begins with interpreting the byte stream of
graphics data from the I/O manager. This is done by a Parser
.
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From HP internal tests on a suite of A1 pages, the average size of bitmap image data files sent over the network was 206MB.
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Spool files of HP-GL/2, RTL, PCL, and PostScript data are typically 10 to 100-times smaller than the bitmap image files they produce. Based on
internal HP tests on a suite of A1 pages, the average size of spool files sent over the network was 6MB compared to 206MB of bitmap image
data for the same pages.
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HP-GL/2, RTL, and PCL3GUI processing is supported. HP Designjet T1100ps-series printers support PDF, JPEG, and TIFF formats and also
feature embedded PostScript.
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The IO Manager handles data streams from the printer’s physical interfaces such as USB, Integrated LAN, and JetDirect EIO cards.