Richard Hughes, the author of colord, developed in the recent months new hardware for measuring monitor colours. The ColorHug called device shall come at a relatively low price. It shall be useable for LCD/LED monitors providing input to calibration and profiling software. The most wide spread open source colour management system, which can create ICC profiles from colour measurements, is Argyll.
The author Richard Hughes states on his blog entry: “Existing hardware is proprietary and 100% closed, and my hardware has a GPL bootloader, GPL firmware image and GPL hardware schematics and PCBs”. The “100%” is a wrong marketing claim as Richard Hughes should know as Argyll user. However the new device fits nicely into a row with prior open source art in colorimeter hardware like the HCFR. The HCFR is supported in Argyll since some years now. To make the new ColorHug device functional, it would be great, if the hardware author could deliver a module instantly useable in Argyll.
What would now be interesting is to know, how the new device will compare with pre existing ones, being them proprietary or open source licensed hardware. The author gave a hint about speed. But speed is only one property useable to reduce noise in dark readings. Much more interesting is colour accuracy.
What is colour accuracy and why is it so important for a colorimeter like the HCFR or the new ColorHug? Colorimeter devices suffer almost all from a difference to the ideal colour reception of human eye, especially the cheaper ones. Only spectrometers can compensate better for that effect of non perfect filters in front of the actual light sensors, but expose other disadvantages. Colorimeter devices, which perform close to human sensibility, are usual expensive. Some are even more expensive than colour spectrometers. Colorimeter manufacturers use a common trick and put a correction matrix inside the device, which shall compensate for the difference between the sensitivity of human eyes and the colorimeter. But many users complained not to be able to get good results despite. This is easily understandable, as monitors emit light with very different spectral characteristics, which do not match the used filter in the colorimeter and its matrix. One approach to get better results is to use a per monitor model compensation matrix. Fortunately Argyll has implemented compensation matrices in one of its recent releases. The requirement for this approach to work is, that the data base needs input data from users.