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Measuring Color Temperature

O

Olaf Schultz

Jan 1, 1970
0
Moin moin,

is there a way, to ,,measure'' the correlated color temperature of a
light-source (LEDs) without special equipment. GMC, Minolta etc. costs
about 1k Euro and above, for a non-profit-job a little bit to much.

Theres no need to be on the K exact..but approx. +-100K would be nice:)

I thought about taking a digital camera (e.g. Olympus E3), fix it to a
defined colour temperature, take a foto of the light (OK, look in an
integrating sphare, painted with BaS04, available are somes:) and
calculate about the averaged colour of the picture the colour-
temperature.

Maybe the camera has to be calibrated with a known light-temperature:
1. sun (with a cutout of a tele-foto)
2. blue sky (mhm...AFAIK not very constant:-(
3. tungsten-lamp (mhm)
I would perfer 1....other hints?

Has anybody already made this way? Or a better hint?

Just as boundary condition: Sorry, no Windows, so no Photoshop...but
Linux with its tools and already programmed reading and converting pnm is
not that problem to make also some statistik on this.

Greetings from nothern germany,

Olaf Schultz
 
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