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Canon iPF6450 SU-21 spectrophotometer use

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Canon iPF6450 SU-21 spectrophotometer use

An overview of the SU-21

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The iPF6450 is the higher end model of Canon’s 24″ large format printers, with an internal disk drive.

It also supports the SU-21 spectrophotometer unit (the grey box along the front of the printer, in the photo). The SU-21 does not work with the iPF6400 – there is no connector for the spectro on the printer.

We’ve had an iPF6450 here for a while to try out and Keith has written a lengthy review of the 6450/6400 printer.

The printer was kindly loaned to us by Canon UK and included an SU-21.

This short review covers some basic testing of the SU-21 with the supplied Canon software, although where such a device is warranted, you might be more likely to use it in conjunction with a RIP to drive it.

Do remember that our printer reviews are focused much more at the fine art/photography printing market, so the SU-21, which is really aimed at prepress and proofing, is somewhat less relevant to the types of printing we do.

6450 SU21 spectrophotometer

Keith has also written two short guides to the process of assembling the printer and the spectrophotometer unit.

The Canon SU-21 spectrophotometer

The SU21 unit contains a scanning unit with an X-Rite spectrophotometer.

This reads coloured patches from prints, which may be used for printer/media calibration, and profiling. The device also contains a blower unit that speeds up drying time before measurements can be taken.

Key features are listed by Canon as:

  • The sensor’s fully automated mobile carriage provides the ability to use media of different thicknesses
  • Includes a user switchable single-piece backing plate
  • The user-switchable UV blocking filter can be switched on and off according to the paper type
  • Scan speed of 10.0″ per second
  • Generate colour calibration charts for 3rd party media
  • ISO 13655 compliant
  • Complies with 2010 XRGA measurement standards

Using the SU-21

The device is directly controlled via the printer, and has electrical connections (via the stand) for power and control signals.

At the heart of the device is an X-rite spectrophotometer, which clips into place in the scanning unit (mouse over image to see)

Original ImageHover Image

The spectrophotometer is used to scan over output from the printer, using either a white or black substrate.

There is also a (cleanable) white calibration tile in the unit. You can see more details of the unit’s construction in the SU-21 assembly article.

The XRGA compatible spectrophotometer offers UV cut and UV non cut measurements and is based on the technology used in my own i1 Pro 2 spectrophotometer and i1 iSis that I use with X-rite’s i1 Profiler software for a lot of my printer profiling.

One problem with a built in spectrophotometer is drying the print before measuring the colour of the printed target patches. For most papers I’ll leave overnight before measuring, although I know that on many gloss/lustre papers, the Canon Lucia inks are OK to read a lot sooner.

The SU-21 unit gets round this issue by including a powerful ‘blower’ unit that force dries media before measurement. The whole printing/measuring process is carefully balanced to the minimise total time taken.

Since I don’t work in a busy press/proofing environment it’s difficult for me to meaningfully judge actual performance, but the quick test of profiling I look at later took well under an hour.


Basic printer calibration is performed using the sensors attached to the print head, however, if you have an SU-21 attached, then it’s also used in this process.

The test prints below are what was produced (the first grey alignment target is still measured by the head sensors)

printer calibration.

Calibration targets can also be created and measured as part of the custom media settings process outlined in the main iPF6400/6450 review.

The print/measurement process takes a while longer than without the SU-21, since the paper is force dried.

Move your mouse over the image below to see the measurement unit being raised and lowered.

Original ImageHover Image

Canon have a PDF document describing calibration linking (between printers) that may be of interest, if you are looking at a larger print setup.

Canon Colour Calibration Management Console

The supplied software is designed for creating and organising calibration and measurement data for one or more iPFx400 printers.

“Color Calibration Management Console is software that allows you to determine the color calibration status and execute remote color calibration on multiple printers. It allows you to acquire color measurement data and execute color checks on printers mounted with a spectrophotometer unit.”

Connected printers are shown in a list (both network and direct USB connections)

The little colour symbol spectro present indicator symbol, by a printer name shows that it has a spectrophotometer connected.

canon colour software

I’m going to show a fairly basic example of printing a target and using the data to create a profile with external software.

The software takes a step by step process, that is clear and easy to follow (there is additional help available, although it is more operational help, rather than offering any explanation of what you are doing and why)

workflow steps

Previous runs are recorded in a named execution log – in this instance I’m new to the software, so there are no others listed.

choosing a preset profiling and measurement setup

There are two ‘built in’ targets available (see later for more about this). You can select others but note that you can only select colour charts that are CGATS RGB format.

selecting test chart file

The test chart is shown, as it will be printed on your chosen media type.

preview of test chart

The X-rite spectrophotometer allows for quite a range of measurement options.

This functionality is available for 3rd party software developers to use when including the SU-21 in a RIP product.

colour measurement settings

The paper in this instance is a fairly heavy matte art paper, so I don’t really want to reduce the print drying time.

colour measurement setting for using spectrophotmeter

A quick check of the settings before starting things off…

checking profile print and measurement settings

The printer then just does it’s stuff for a while, with printing, drying and patch reading all automated.

print and measurement process

Some half hour later I’ve a printed and measured test chart.

printed profiling target

I need to export the data to work on it.

The standard CGATS format is widely used, and works fine with my copy of i1Profiler.

setting data export format

Here’s the data, being loaded into i1Profiler.

loading data into icc profiling application

Shortly afterwards, I have an ICC printer profile.

profile created in i1Profiler

The profile works just fine, however, with a printer like this I would normally want to use more than a basic 918 patch target.

Bigger patch sets?

it is possible to include larger patch sets, such as this ~2700 patch one from i1Profiler.

If you want to see more about the used file formats, you can find the two ‘built in’ TC2.83 and TC9.18 targets within the application (‘show package contents’ for the application, on a Mac – not sure where on a PC I’m afraid).

setup for testing larger profiling targets

Zooming in to the view of the target, shows its label.

zoomed view of target, showing label

Unfortunately my various attempts at printing the bigger targets all failed (at several different print settings). The documentation doesn’t cover this particular aspect of using the SU-21. Given that the application only outputs data in a relatively basic form (no spectral data) I’d not choose it for my own advanced profiling.

Canon provide a software development kit (SDK) for software developers (of RIPs and the like) where you could make much more use of the spectrophotometer functionality and potentially use it for linearisation and profiling.

As I said, it’s not really a tool aimed at the sort of fine art/photographic print market I’m in, but interesting to see in action…


A very impressive bit of kit that with its speed and measurement options will find ready use in commercial print settings.

The SU-21 unit is huge though, and makes the iPF6450+SU21 unit take up more space. It increases depth from ~670mm for the basic printer to ~860mm

I’m 6 foot tall and found heavy roll paper handling more difficult with the SU-21 in place.
This means that if you really must employ shorter members of staff, they won’t easily be able to reach the rear roll paper holder, without getting to the back of the printer ;-)

The print drying action (with the built in blower) seems very effective, allowing measurements appreciably sooner than by using normal air drying.

Article history: First published July 2013


Optional spectrophotometer unit, for attaching to the front of the Canon iPF6450 24″ printer.

Aimed at the print and proofing market, where a single iPF6450 and spectrophotometer can handle calibration and profiling for a group of Canon iPFx4xx printers.

Canon supply a SDK for RIP developers, to get the best from the built in X-rite (XRGA compatible) spectrophotometer.

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