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Frequently Asked Questions

What do the LEDs mean

There are two leds in the ColorHug, one green and one red. The LEDs are used in the following way:

  • Both LEDs flash on then off for a split second when the hardware is plugged in.
  • The green LED flashes quickly three times when the sensor is locked.
  • The red and green LEDs flash slowly alternately when the device is in bootloader mode and needs reflashing with new firmware.
  • The red LED displays morse code in the event of a fatal device error.

Why do I have to hold the device against the screen

Suckers have been known to damage LCD screens by lifting off the top layer of glass. I can't risk this kind of damage, as there's simply not enough profit in each ColorHug to refund the repair costs of displays. When calibrating each ColorHug I use a large rubber band to hold the device to the screen. This works suprisingly well. If you've got a good idea that doesn't involve suckers, please let us know!

Why is my screen "wrong" after calibrating

If your screen differs much from the idealized sRGB that the ColorHug is calibrated against then the calibration result may be far from ideal. This may happen if you are using an expensive LED display, or a minature embedded LCD with low bit depth DAC.

To fix this, you just need to load a correction matrix that's close to your display technology using the colorhug-ccmx GUI program. At the moment there are not many display types, but this will increase when those in the ColorHug community with a photospectrometer start contributing matrices. It's a typical chicken and egg problem, although if you join the colorhug-users google group I'll announce new matrices when they are uploaded.

If you've already got a photospectrometer (or can borrow one for a few hours) then please follow the directions here. If you contribute the resuling CCMX file back to us, we can share it with other users and improve their calibration result too. I'm especially interested in odd display types, as these will be very different from the calibration target.

What is lost-or-stolen mode?

When we send the ColorHug device to you, we give you the choice of postage methods, as we understand a lot of people don't want to pay £9 postage for an item that only costs £48. Using untracked postage means that packages can get lost during tracking, and due to the distance selling regulations of the UK, any lost packages have to be refunded by the seller to the buyer.

In order to deter unscrupulous buyers, any packages that are registered as lost or stolen will have the ColorHug devices added to a blacklist. This means that anybody trying to update the firmware on a device that is registered as lost or stolen will have the hardware disabled. Serial numbers will not be added to this list for any other reason.

What data is transmitted to hughski.com?

If you choose to update the firmware on your device, the colorhug-flash program contacts hughski.com and downloads the list of all the firmware updates. When it does that, the following data is sent to the server:

  • Your IP address
  • The current version of the firmware
  • The hardware version of the device
  • The serial number of the device (e.g. #000337)

We don't actually use this data for anything other than working out what firmware is available to you and any logs are automatically overwritten after 30 days.

The only time any data is transfered to the server is when you update the firmware or download new CCMX matrices, and certainly not for each calibration or sample!

I've erased my factory calibration!

If you're got colorhug-client 0.1.4 or newer installed, just run colorhug-ccmx and you should be presented with the following dialog:

Then just click Repair and the device will be back to normal.

If you're running an older version of the colorhug tools, simply find the correct ccmx file from the archive and perform the following steps: 

[user@localhost ~]$ /usr/libexec/colorhug get-serial-number
000043
[user@localhost ~]$ /usr/libexec/colorhug set-calibration-ccmx 0 ./calibration-000043.ccmx
[user@localhost ~]$ /usr/libexec/colorhug set-calibration-map 0 0 0 0 0 0
[user@localhost ~]$ /usr/libexec/colorhug write-eeprom "Un1c0rn2"

What payment methods are accepted?

The preferred way of paying for a device is using Paypal as it's easy for me to track payments and issue refunds. If you've got ideological problems with Paypal, or would rather not use them, then email me when you get the offer to purchase a device and I'll give you my IBAN and BIC numbers for a direct bank transfer.

I've found a bug or missing feature, what do I do?

Just file a bug in our bugzilla issue tracker. Be sure to write as much detail as possible in the bug report.