Batch color correction among lenses

[fsenore (Fulvio Senore)]

I sometimes use some old lenses adapted to my Panasonic GX7.
A few days ago I used a Nikkor 50mm: it works very well but colors are rather different and this is sometimes annoying. If I load in RawTherapee 5.6 two images, one shot with the Nikkor and another shot with a Panasonic lens, I can change the white balance of the Nikkor one (temperature and tint) to match the two images.

Is there a way to automate this change with a single command, so that I can easily match colors among images taken with different lenses?

Thanks in advance.

Fulvio Senore

[Sunhillow (Hansgeorg)]

Hi Fulvio,
you might create a profile that only applies colour correction to your images.
Or use dynamic profiles, but then you will have to use exiftool to insert the lens data into your RAW files.

[fsenore (Fulvio Senore)]

Thank you for your suggestion.

Is it possible to specify a relative correction for the white balance (for example -500K)?

Since photographs can be taken with different color temperatures I think that I need a way, for example, to lower the color temperature by a fixed amount.

If a profile can only specify an absolute value for the color temperature then it is not very useful to solve my problem.

[heckflosse (Ingo Weyrich)]

@fsenore

Is it possible to specify a relative correction for the white balance (for example -500K)?

That’s possible in batch edit mode. First you have to set the mode for whitebalance like this:

Then in filebrowser select the files you want to add the values, go to batch edit tab and enter -500 for temperature

[Morgan_Hardwood]

Big hairy but! The temperature response is not linear, so always subtracting 300°K will have negligible effect at temperatures around 10000°K and huge effect at 2800°K.

@fsenore

A few days ago I used a Nikkor 50mm: it works very well but colors are rather different

If I was in that situation, I would create a custom DCP input profile for that lens. But that’s just me.

[fsenore (Fulvio Senore)]

Thank you for your help, I did’n know that it could be done.

[fsenore (Fulvio Senore)]

@Morgan_Hardwood

Big hairy but! The temperature response is not linear, so always subtracting 300°K will have negligible effect at temperatures around 10000°K and huge effect at 2800°K.

Thank you for the info, but I plan to shoot in daylight conditions, so color temperature will not change very much from shot to shot.

@Morgan_Hardwood

@fsenore

A few days ago I used a Nikkor 50mm: it works very well but colors are rather different

If I was in that situation, I would create a custom DCP input profile for that lens. But that’s just me.

I tried. I photographed a colorchecker with that lens and I created a DCP profile with the X-Rite software, but the profile did not change the white balance so the difference was minimal. Is there a way to change the color balance in a DCP profile?

[ggbutcher (Glenn Butcher)]

@fsenore

Is there a way to change the color balance in a DCP profile?

I hear not, probably for the way DCPs handle white balance with dual-illuminant primaries. I have corrected white balance with an ICC profile, built with Argyll tools, from an uncorrected TIFF. In raw processing, the conversion takes place when the post-demosaic RGB image is converted from camera space (this ICC profile) to the working profile. In the comparisons I made between it and ‘regular’ mulitplier-based WB correction, the profile-corrected ones seemed to hold on to more color saturation.