How to edit camconst.json please

Software RawTherapee
1

hi, the notes in this file say to put your own version ‘next to your personal “options” file’, however I’m unclear - there is a file called options but it’s in the same folder as camconst.json. Where exactly does a tailored file go, please, and do you call it camconst.json? (Windows platform)

I want to experiment with the white point settings for my EOS 6D, do I edit the items in bold below? Is re-naming it a text file and using Notepad ok to edit it, then naming it back to camconst.json?
Any tips will be much appreciated. Following getting some pink highlights the other day, I want to check out some samples with the white point slider in the RAW tab, and possibly adjust the white point values in camconst. thanks.

…{ // Quality A, some missing scaling factors are safelly guessed - most samples by sfink16 at RT forums
“make_model”: “Canon EOS 6D”,
“dcraw_matrix”: [ 7034,-804,-1014,-4420,12564,2058,-851,1994,5758 ],
“ranges”: {
“white”: [
{ “iso”: [ 50, 100, 125, 200, 250, 400, 500, 800, 1000, 1600, 2000, 3200, 4000, 6400, 8000, 12800, 16000, 25600 ], “levels”: 15180 }, // typical 15283
{ “iso”: [ 160, 320, 640, 1250, 2500, 5000, 10000, 20000 ], “levels”: 13100 }, // typical 13225
{ “iso”: [ 51200, 102400 ], “levels”: 16280 } // typical 16383
],
“white_max”: 16383,
…

2

There should be another options file in your home folder. On linux it’s ~/.config/RawTherapee/.
I think on windows it’s \Users$USER\RawTherapee\ or something like that.

3

Morning!

Your personal option folder is located here on Win 7/64b:
C:\Users\YourUserName\AppData\Local\RawTherapee

Just copy the original camconst.json from the program folder
into the personal option folder and change whatever data you want to
alter. Keep the original filename, i.e. camconst.json.

4

hi, thanks for the above. But I am STRUGGLING! - need some help please.
I’ve amended a copy of the file in the local folder as @Claes says, but it makes no difference. I’ve put in high values (30,000) and then low values (2,000) expecting to see dramatic differences in RT. But nothing is changing. Before each test I’m deleting the PP3 file that partners the raw file, and deleting all the local …rawtherapee\cache\ files in case they are “remembering” any values.

I don’t have a good feeling about this. The camconst file seems to make very little difference at all. I can rename it to Kamconst.json in the main program files folder, check there are no instances of camconst anywhere, and yet RT fires up ok and when I open the raw file I’m using for these tests, it’s hardly any different as compared with when camconst is present. The pink area on the birds neck (see my other recent post which led to all this!) is less pink with camconst present, but the rest of the image is the same to my eyes.

“Camera standard” is set as the input profile under colour management.
All this is with RT 4.2.745 Win7 32 bit. Camconst’s amended date is 28/2/2016 15:43, a month old.
EOS 6D cam. Samyang lens shown as unknown.
I’ve uploaded my amended camconst files here: http://filebin.net/esn3w31ezn

Please help, hair will be torn out soon…!
Andrew

5

Relax & save your hair!
I am a little on thin ice here (or perhaps thin hair?),
but please go to tab Color/Color Management.
Can you select option Auto-matched camera profile?
Can you select DCP option Tone curve?

6

hi again & thanks for replying.
Can you select option Auto-matched camera profile? No, this is greyed out regardless of the other settings I can do (no profile, cam standard, custom).
I can select the custom 6D profile that came with RT and this makes a small change compared to cam standard.
Clicking tone curve gives a better histogram and image.
But I’m doing all this with low white values in camconst.json in my user profile. I’d expect the image to be very burnt out but it’s fine!
This is my problem - I want to see these camconst values having an effect, so that I can then go on to tweak them knowing I’m not wasting my time.
Andrew

7

P.S. Auto-levels is OFF

8

Hmmm… I will make a few experiments and will report back.

9

Evening, Andrew!

I am not much wiser after my experiments.
I have Win7/64b and RT 4.2.880. I can confirm that
RT really does fetch the camconst.json located in
my personal option folder. Sorry, but I do not have
any fresh ideas – let us hope that the guys with more hair
on their chests (or whatever) will return from
Blåkulla soon so that they may be able to assist you.

Until then, if you are really desperate: how about a complete save/uninstall/clean everything/re-install RT?

In the meantime, have you seen this? camconst.json is mentioned a few screens down.

Claes

10

Thanks again Claes. I think the witches have put a spell on me…
The link to the calibration article is interesting, though rather advanced for me.
So, have you changed settings in your personal camconst and found them to take effect? What camera is this for please?
I might do as you suggest and re-install this coming week. When you say “clean”, I guess you mean delete any folders that belong to RT?
Have you edited camconst and if so, what editor did you use? (Long shot, but just wondering if Notepad could be messing up the format or something)
Andrew

11

Yes, I changed the personal camconst.json file.
I entered some very odd numbers for my camera (Fuji X-T1) and started RT 4.2.880
on my Win7/64b. RT refused to open/edit a photo. I put back the original numbers in
camconst and then RT worked the way it should again.

I performed the same trick in Linux/Ubuntu and the nightly version of RT.
Here RT opened the photo, showing it all green. Note: I did not enter the same
fake data as in the Win version.

You are right: notepad adds CR LF. I used the Windows version of Vim.

Correct: by “clean” I mean just that, including your personal RT folder.
Don’t forget to save off (to somewhere else) any data you would like to keep.

Claes

12

You could try a freeware program named Notepad++. It’s perfect for editing text files and can also make edits to files written in many common languages (C, C++, Perl, Assembly, to name a few).

13

I’ve had another go at this, and Notepad++ has sorted it, thanks @fasteddie. To save others the frustration I’ve had, here’s a suggestion for some extra explanation at the top of the camconst file - maybe someone can include this?-

DO NOT EDIT THIS FILE!

All changes made here will be lost on software update. If you want to add custom values or changes existing ones, create a “camconst.json” file next to your personal “options” file. Its values will then override and/or complete the ones of this file.

If you add values for your own camera and are okay to share them with RawTherapee’s community, please drop a link on the user’s forum.

Under Windows, a personal camconst file needs to be in
C:\Users<user name>\AppData\Local\RawTherapee
Do not edit the file with Windows Notepad - it messes up the file. Notepad++ supports JSON files and can be obtained here at the time of writing (April2016) :-
https://notepad-plus-plus.org/

and so on…

Andrew

14

Your file path presumably is for Win 7/32b.
On Win 7/64b it is C:\Users\YourUserName\AppData\Local\RawTherapee

Claes

15

hi @Claes, good point! My path above is wrong, missing the user name. I typed it in when I wrote the post in angle brackets, but the “system” has removed this part of the text! I just tried it now to check I’m not imagining it! C:\Users\left angle brk user name right angle brk\Appdata… comes out as C:\Users\Appdata. HTML thing? Andrew