Using multiple ColorHug at the same time.

[niklas....@gmail.com]

Hi,

I have what I suspect is a somewhat uncommon problem. I'm a PostDoc at the university clinic in Hamburg and I'm setting up an experiment to investigate certain types of decision making. For this experiment I'd like to show two gratings which are rear-projected onto a screen. Everything happens in a MEG scanner and I can't use a normal screen but have to project the image via  a series of mirrors into a magnetically shielded room.  This (and the projector we use) creates strong luminance inhomogeneities.

Since I want to be able to control what my participants see I'd like to measure and eventually correct these inhomogeneities. And since the projection screen moves a bit every time a new participant enters the scanner I'd really like to profile the projector at the locations where I show the two gratings. For this I had planned to attach two ColorHugs  to the screen. I want to use two at the same time because the time someone can spend in the MEG is limited. I've started to play around with one and I can successfully take readings from the device, which I hope to then be able to use to correct for luminance and color differences at the two locations.

My problem is that colorhug-cmd complains as soon as I plug in a second ColorHug with the following error message:
No connection to device: Multiple ColorHug devices are attached

My question is: Is there some more or less easy way to extend the ColorHug client to selectively read from one of several attached devices?

Any help would be appreciated,
Niklas

PS: The color hug reports hardware version 1  and firmware version 1.1.6

[Graeme Gill]

niklas....@gmail.com wrote:

> My problem is that colorhug-cmd complains as soon as I plug in a second
> ColorHug with the following error message:
> No connection to device: Multiple ColorHug devices are attached

The ArgyllCMS tools should cope with multiple ColorHugs (and other
instruments). You just have to use the -c parameter to specify which
instrument you want to use, and you can fire up multiple copies
of the tools.

Graeme Gill.

[niklas....@gmail.com]

Thanks a lot! Works like a charm.

Niklas

[Richard Hughes]

On 12 June 2015 at 15:59, <niklas....@gmail.com> wrote:
> My question is: Is there some more or less easy way to extend the ColorHug
> client to selectively read from one of several attached devices?

I've added this support in this commit:
https://github.com/hughski/colorhug-client/commit/6f653497a8c4e7d9071a40ece81c01c6dd108d13

Richard.

[niklas....@gmail.com]

Very cool! Will check this out as soon as possible.

Niklas