WB presets - displayed values

Software ART
1

Hi,
meanwhile the Wb presets are selectable in ART
But I see that the displayed values in ART are different to the values in RT (same raw file; same camera).
Examples:

  • as shot: RT= 3616K; ART=3652K
  • Daylight: RT=5300K; ART=4806K
  • cloudy: RT=6200K; ART=5460K
  • shadow: RT=7600K; ART=6619K

The intersting thing: the resulting colors are more or less identical between RT and ART.
The values of RT are similar to the values you get in LR and C1

It looks like a “calculation error” in ART ?..perhaps an easy fix?

BR Thomas

2

Hi,

well, not necessarily – see below. In any case, do you have some more detail about this?

More specifically: as far as I know, RT doesn’t have camera-specific WB presets, it uses hardcoded values for daylight, shade, etc. which might or might not work well with your camera.
As for differences in the reported values of temp/tint in “as shot” mode, they could depend on different camera to xyz conversion matrices used by the two programs (in the case of ART vs RT), or different conversion algorithms between WB multipliers and a temp/tint pair (in the case of ART vs commercial apps).
In both cases, the differences can be explained even without postulating that there is a “calculation error”. Of course such error might still be there, that’s why I was asking for more details :slight_smile:

HTH

3

…this is what I added in the wbpresets.json file:

"make_model" : "SONY ILCA-99M2",
"presets" : [
  {"name" : "Tageslicht", "multipliers" : [2.293, 1, 1.633]},  **4806 K**
  {"name" : "Bewölkt", "multipliers" : [2.484, 1, 1.492]},**5460 K**
  {"name" : "Schatten", "multipliers" : [2.746, 1, 1.3398]},**6619 K**
  {"name" : "Glühlampe", "multipliers" : [1.402, 1, 2.980]}, **2613 K**
  {"name" : "Blitz", "multipliers" : [2.531, 1, 1.468]},**5621 K**
  {"name" : "4500 K", "multipliers" : [2.066, 1, 1.8398]}, **4163 K**
  {"name" : "6000 K", "multipliers" : [2.4609, 1, 1.5078]}, **5374 K**
  {"name" : "8500 k", "multipliers" : [2.890, 1, 1.269]} **7483 K**

I took these values out of exiftool and re-calculated as described by you in another post.Tthe numbers with the stars are the values I see in ART.
Are these information helpful or do you need other information?..please let me know…

BR Thomas

4

Sorry, I think I was unclear. My claim is that there is no bug , and that the difference in behaviour can be explained as in my first reply. If you think I’m wrong (definitely possible!), I’d ask you to explain to me why. Otherwise I’m sticking with my explanation :slight_smile:

Best

5

Let me add: there is no unique way to go from WB multipliers to a temperature value, there are different methods, and they are all approximations. So some differences in the results are to be expected, and nothing to be worried about.

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6

…I believe that the WB values in RT, LR and C1 are hard coded as described by you.
This is the most important information for me!
The only thing I do not understand:
The camera setting says: take “daylight” and ART shows 4806 k.
This is the discrepancy I see…and common practice when talking about WB=daylight means values from 5300…5500 K.
But you are right…as already mentioned…the colors are correct independent of the displayed numbers.
So feel free to spent a few minutes to investigate… :grinning:

BR Thomas

7

what camera are you using?

8

it is a Sony ILCA 99M2

9

For what it’s worth, on another graphics forum someone posted about possible WB errors and asked for comparison numbers. I took the same image in ART, RT, darktable, Affinity Photo, Canon DPP and maybe even a couple of other raw editors. Not a single WB number matched between them all.

So, this is not unusual. :smiley:

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10

…it looks like that I have to live with the current status.

Nevertheless…thanks for the clarifications

BR Thomas

11

I’m afraid I don’t understand what you were expecting exactly. You asked a question, you got multiple answers trying to explain what is going on…
:man_shrugging:

12

Hello Alberto,

sorry If you missunderstand my last answer…
for me everything is fine…I get comments and answers

BR
Thomas

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