I have a Panasonic S5 camera with an astro modified filter for night photography (basically it extends a little bit into the IR to capture also the Ha emissions). Due to this, the Auto WB and other WB presets are no longer working as intended. Therefore, I am using one of the user defined WB slots, where I set up the temperature to 3000K and a little green tilt.
However, when the images are displayed in ART, the implicit WB is ‘As Shot’ and it shows a temperature of 2834K and a 0.967 tint (goes towards magenta).
Hi,
“As shot” takes the channel multipliers from the image metadata, as recorded by the camera. The conversion to temp/tint is an approximation, and there are multiple slightly different methods to do it. Also, it depends on the camera to xyz conversion method used (in the case of art, a simple matrix for what concerns wb). It’s quite likely that Panasonic is using a slightly different method, so all things considered I’d say that the values you get are not terribly off…
Bottom line, what you get in “as shot” mode should correspond to what you set in the camera. If you have (visual) evidence of the contrary, I would consider that a bug.
Thanks for the clarification.
I would say that visually, what ART shows with the ‘Default’ processing profile (which includes WB with ‘As shot’) looks similar to what the camera preview shows (as much as the color profile of a small camera LCD can match the one from a Macbook retina display …). I was only a bit puzzled about why the temperature is shown other than 3000K what was set in the camera.
I do not consider this a bug, in the end the WB part is not a science and will be set anyway to whatever value makes things look good.
How exactly should ART do the white balance exactly like the one in the camera, when I use: “As sthot”?
Here, with my Panasonic S5M2, ART makes the images significantly less red, but more yellowish. Is this difference normal, or is it too big?
“As shot” is not calculated, it’s taken directly from the image metadata.
However, there might be many reasons why art’s rendering is different from the camera one, including differences in the input profile, in the wb algorithm, and generally different processing pipelines. Wb is only one aspect, and not necessarily the one with the biggest impact.
Matching the camera precisely under different shooting conditions is very hard…
I think in another post you mention that you use the automatched curve. I think ART uses neutral and RT the film model by default but choosing one of the other models for your curve will dramatically or can dramatically impact color so it might not be a simple WB thing but rather the model of the curve that you are applying… I would be curious to know if you have tested the different ones for the “look” of your images…
Hello @priort
I used “Auto-Matched Tone Curve” and if I switch it off, it’s difficult to compare the result with that of the camera, because then I have to increase the contrast and saturation manually. And then the question is how much, because that influences the result a lot.
I can live with the differences as long as I am sure that they are normal and do not indicate a fault.
I just realized, there are also shots in which the colors of ART with Auto-Matched Tone Curve and the internal Jpeg of the RW2 are completely identical.
When the camera bandpass filtering was modified, you abrogated any expectation that the camera WB settings or algorithms will work as intended.
I’d focus more on what RGB white balance multipliers do what you need. Temp/Tint are more properly a function of the lighting in the scene anyway, left that behind when you took the picture…
Ya I wasn’t really suggesting that you turn it off here but rather compare the curve model options for the look of the colors…there are about 6 options and the look can be different … you mentioned wb but it might not really be much to do with wb and the saturation the red etc etc could also be tied to the model that you are using …and maybe not so much but it might be nice to cycle through then and look and see…just experimentation…
