Re: Standard Light A?
Re: Standard Light A?
- Subject: Re: Standard Light A?
- From: Andrew Rodney via colorsync-users <email@hidden>
- Date: Thu, 6 Oct 2022 14:39:52 -0600
On Oct 6, 2022, at 2:23 PM, Jeff Nova via colorsync-users
<email@hidden> wrote:
>
> I keep seeing "Standard Light A" in DNG metadata. Presumably this is just
> Standard Illuminant A? Just making doubly sure.
>
You see it where (and which tag)?
You might find the answer here:
https://www.kronometric.org/phot/processing/DNG/dng_spec_1.4.0.0.pdf
<https://www.kronometric.org/phot/processing/DNG/dng_spec_1.4.0.0.pdf>
"One or Two Color Calibrations
DNG provides for one or two sets of color calibration tags, each set optimized
for a different
illuminant. If both sets of color calibration tags are included, then the raw
converter should
interpolate between the calibrations based on the white balance selected by the
user.
If two calibrations are included, then it is recommended that one of the
calibrations be for a
low color temperature illuminant (e.g., Standard-A) and the second calibration
illuminant be
for a higher color temperature illuminant (e.g., D55 or D65). This combination
has been found
to work well for a wide range of real-world digital camera images.
DNG versions earlier than 1.2.0.0 allow the raw converter to choose the
interpolation
algorithm. DNG 1.2.0.0 and later requires a specific interpolation algorithm:
linear
interpolation using inverse correlated color temperature.
To find the interpolation weighting factor between the two tag sets, find the
correlated color
for the user-selected white balance and the two calibration illuminants. If the
temperature white balance temperature is between two calibration illuminant
temperatures, then invert all
the temperatures and use linear interpolation. Otherwise, use the closest
calibration tag set".
Andrew Rodney
http://www.digitaldog.net/ <http://www.digitaldog.net/>
_______________________________________________
Do not post admin requests to the list. They will be ignored.
colorsync-users mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden