I’ve been using RT regularly for about 8 months - so a newbie. I’m using the latest stable dev version - on linux Suse with an Argyll calibrated monitor.
I have a Panasonic G90 and a GX9. The poor man’s Olympus - in the days when photographs were real, printed on paper from negatives, I had an Olympus and figured if they use micro 4/3 then it can’t be all bad. The GX9 is for travelling and wandering the streets - with a 20mm lens it’s invisible under a coat.
In terms of sensor, processing, they are the same beast. The difference is in access to controls and handling.
Here’s the problem - and the must read solution for Panasonic users at the end.
For all that time I’ve been battling with nearly every image (from what I’ve said above - from both cameras) having a distinct magenta cast. Reading Rawpedia I was told that I shouldn’t need to touch the white balance and should use colour toning to rectify it, which I obediently tried to do.
I also set about making my own double illuminant profile using Dcamprof. This had a slight mitigating effect. But by no means enough.
I then started looking at EXIF data and discovered that RT was systematically around 250°K out - so I did start playing with white balance - including playing with the red (magenta - I do wish people were specific about colour names)-green axis.
Finally confronted with a particularly egregious set of magenta images and looking at one of the new histograms in the dev version, I resorted to manipulating the black levels. I found I got mostly good results from setting R to +6 and B to +4 - didn’t always work but playing with it seems to have solved the problem. I now have just to work through 1500 images applying the solution…
However there is an easier solution (tried in desperation) : in the options in-camera there is a choice of colour space : either SRGB or AdobeRGB. SRGB is the default but I switched it to Adobe. In EXIF it changes from SRGB to uncalibrated. And suddenly RT works as it should… no more colour cast - just the colour temperature wrong.
So for Panasonic users using the AdobeRGB (uncalibrated) colour space is essential to work with RT
My questions are (1) What causes the different behaviour with the change in in-camera colour space?
and (2) Does this mean I have to redo my colour profile - which was done using in-camera SRGB?