Tuesday, July 15, 2008

Colorimeter measurement supports a claim of the iPhone yellow screen fix with the 5A347 release.

There were reports regarding the iPhone 3G screen being too yellow.
It looked absolutely fine on the iPhone I got.

Later still many have claimed [AppleInsider] that the restore to the 5A347 release from 5A345 "fixes" the "problem".
So, I used my trusty Gretag Macbeth i1 spectrometer to see for myself.

First I would measure the white and gray fields on the iPhone with 5A345 set at the medium brightness with the auto brightness adjustment disabled, then I performed the restore to the 5A347, using the iTunes and repeated the measurements under the same conditions.

To begin with the original measurement showed the white point set to 5500K, which is awesome, and as many of you know is a standard for the many industries as far as the color management is concerned. CRI of 75 with white point brightness of 246 lux.

After the software restore the numbers were as such: 5755K, CRI = 74 and the brightness of the wight point at 241 lux.

For those of you unfamiliar with the color temperature concept, 5500K is yellower then 5755K.
The color curve showed no change in the blue part of the spectrum but some (very minimal) tweaking in the green and red, significantly more so in the green. This goes well with the whole change in the yellowishness theory.

So here you go, real, hardware measured data.

Subjectively though, I could not see any difference and I found the color rendition to be perfect on the original release anyway.

Measurement methodology was such: two measurements (averaged) for each brightness, 8 measurements total, with a calibration of the eye-one colorimeter after each sampling.

Questions? Comments?

1 comment:

Anonymous said...

Uh...it's actually 5000 degrees Kelvin -- not 5500 -- which is the lighting standard for photography, printing, and the art world.