O
Olaf Schultz
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
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
andcalculate 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
