[2D] X-Rite Colorchecker SG ruler

There is something weird about the Gretag Macbeth X-rite ColorChecker SG test target. Today i was working on the universal target software, working out the DPI from the SG alone. So i was confused about the size it showed. It shows a ruler of 6cm. I doubt anyone uses that though, and i hope no-one does, since it seems that they have (although i still think i have overlooked something because this is such a huge flaw) made an error of some kind. The ‘0’ locator is written underneath the 0.1 mark, and the ‘0’ mark is inexistant. So either “0” should say “0.1” or they have do add another bar. It might be me, but the last time i looked rulers started at 0.0..

<UPDATE> contacted X-Rite about this

“Thank you for contacting X-Rite regarding Product Support. This is an automated message. An X-Rite representative will be in touch with you by phone or email.”

“Dear Tim,
it seems you have identified a printing error which we have to correct on the next edition.

But this doesn’t take any effect on the chart.
Wolfgang Renner”

This was not the response i was hoping for. They do not see this is not only a ‘stupid’ mistake, but can also have consequences when you are calibrating a setup for lets say 300dpi (which will then be 295dpi, if you think that 59mm is in fact 59mm). This is more than a commonly used 1% threshold. So i replied

” This does have an effect on the chart. Say you would use the ruler to obtain a resolution of 300dpi. You would then be tuning with 59mm instead of 60mm, thus in fact obtaining a resolution different than 300dpi.

Tim Zaman”

“Yes in this case you have to consider 59 instead of 60 mm …
Of course we have addressed this issue to the product manager in charge take corrective actions.

Wolfgang Renner, Technical Support Specialist”


Error is STILL in the newly produced SG targets.

Tim Zaman

MSc Biorobotics. Specialization in computer vision and deep learning. Works at NVIDIA.

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