[argyllcms] Re: Support for free hardware profilers

Frédéric wrote:
I would like to know if there are some free hardware profiler projects (for CRT/LCD)?

In France there is something to calibrate video-projectors; it is not designed to generate ICC profiles, but I was wondering if it could be supported by Argyllcms ? Or do you know other projects like this one which could be supported ?

Link to the french project:

     http://www.homecinema-fr.com/colorimetre


It looks like an interesting project. The key is the sensor, which
seems both an accessible (via Farnell), and convenient colorimetric
sensor (as long as you fit the Hoya CM500 filter to it! - though these
seem harder to obtain than the sensor itself.).

Of course I'd be a bit surprised if it meets the Luther condition
(is equivalent to a CIE observer), but it is possible to compensate
for this to some degree if the spectral characteristics of the
display are roughly known.

They mention the software is GPL, but then it also says
"The associated sources and other files will be issued later.",
so it's unclear whether the PIC micro source is under GPL or not.

Ignoring the above project for the moment, the biggest hassles in
creating a display colorimeter based on such a device are:

 Programming a single chip micro to do the sensor to USB interface.
 Most of these micros are still at the 8 bit assembler level,
 and it's often relatively expensive to do a one off setup for
 programming them the development kits are typically one to a few hundred 
dollars).

 Creating and producing suitable PCBs (Printed Circuit Boards)
 (Hmm. I think I have a copy of Protel somewhere, and it wouldn't
 take too much effort to remember how to use it.)

 Creating suitable mechanical arrangements to house the sensor.
 It would need to be something easy to do, yet would have to
 provide the necessary functionality. A mass producable approach
 would involve getting injection moulding setup (an relatively
 expensive step.)

 Calibrating the sensor is expensive to do properly. It would
 be simple enough to calibrate it against some other commercial
 display colorimeters, but to make it a first class device,
 means that you need a good, laboratory standard instrument
 to measure it against (and all the other associated standards).
 Any reputable commercial display measuring instrument will
 have been individually calibrated against some better standard
 (rather than relying on the manufacturing tolerance of the
 sensor.)

 An attempt to manufacture such a thing and sell it, would
 quickly run into some regulatory red tape. The main ones
 would be RFI regulations, and safety regulations (e.g. UL).
 These are not insurmountable, but would require a business
 to take responsibility for the product, and getting
 such approvals costs money. Selling a kit may avoid some of
 these issues.

None of the above is insurmountable given suitable enthusiasm,
and there are plenty of cost vs. quality trade-offs that can be
made, depending on ones goals.

Perhaps adapting the French colorimetre project might be simplest,
if critical parts were available in kit form (ie. the PCB) ?

I didn't really see any reference to kit availability on the
French web pages, but perhaps I missed it.

Graeme Gill.


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