Help on camera color profile

gdraghino

3

« on: 17 / September / 2016, 05:40:23 »

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Hello, I’m from Italy and I’m new here. I discovered this incredible forum looking for information on how to realize a time laps video with a consumer camera.
Now I need help.
I have installed CHDK on PS A710 IS
I have read the topic “New project: camera color profile calculation” (https://chdk.setepontos.com/index.php?topic=390.0), but I really do not understand where I can find the “matrix option of my camera” in which I should copy the matrix values.
Can you help me please? Maybe there is something I misunderstood, I’m not so familiar with English language!
Thanks
Claudio

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waterwingz

12140

Re: Help on camera color profile

« Reply #1 on: 17 / September / 2016, 10:46:43 »

Quote from: gdraghino on 17 / September / 2016, 05:40:23

I have read the topic “New project: camera color profile calculation” (https://chdk.setepontos.com/index.php?topic=390.0), but I really do not understand where I can find the “matrix option of my camera” in which I should copy the matrix values.

The link you have posted is to a very old forum posting.

Why do you think that you need to change the color matrix for your camera? Please tell us a bit more about what you are trying to do. There is most likely a better way than what is referenced in that old link.

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Ported : A1200 SD940 G10 Powershot N G16

gdraghino

3

Re: Help on camera color profile

« Reply #2 on: 17 / September / 2016, 12:49:38 »

Ok it is an old post, but i think it is still valid.
As I told I'm not so confident with english to explain exhaustively waht I'm trying to do.
So I've search the web for a good explanation of what I mean, and here it is :http://ufraw.sourceforge.net/Colors.html
In the old post I've found the color profile for the A710 IS, but I do not understand how I can "copy values of matrix into 'matrix' option of your camera".
But never mind, I'll give up, is not so important.
I just wanted to learn something new.
Thanks in advance
Claudio

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waterwingz

12140

Re: Help on camera color profile

« Reply #3 on: 17 / September / 2016, 13:48:02 »

Quote from: gdraghino on 17 / September / 2016, 12:49:38

Ok it is an old post, but i think it is still valid.

Back when that post was created, people needed to figure out how to calibrate the colors found in their RAW images and then process each image manually. As CHDK developed the ability to use DNG images, that became unnecessary once the calibration information was determined for each camera. The calibration values for each camera can be found in the source code file called platform_camera.h - there is a unique version of this file for each camera. The values are stored like this :

Code: [Select]

    #define CAM_COLORMATRIX1 \
        11093,  1000000,    -3906,  1000000,    -1028,  1000000, \
        -5047,  1000000,    12492,  1000000,     2879,  1000000, \
        -1003,  1000000,     1750,  1000000,     5561,  1000000

So when you ask :

Quote

I really do not understand where I can find the “matrix option of my camera” in which I should copy the matrix values.

then the answer is that you must edit the source file and recompile CHDK.

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Ported : A1200 SD940 G10 Powershot N G16

gdraghino

3

Re: Help on camera color profile

« Reply #4 on: 17 / September / 2016, 17:30:05 »

Now it is clear, but from the original old post it seemed something easier!
Thanks again for your patience!
Claudio

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waterwingz

12140

Re: Help on camera color profile

« Reply #5 on: 17 / September / 2016, 18:16:04 »

Quote from: gdraghino on 17 / September / 2016, 17:30:05

Now it is clear, but from the original old post it seemed something easier!
Thanks again for your patience!
Claudio

In that earlier thread, they were also talking about using a program ( Dng4ps2.exe ) on the PC to adjust color balance. As far as I know, that program is pretty old and has not been updated in six or seven years?

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Ported : A1200 SD940 G10 Powershot N G16

Ant

509

Re: Help on camera color profile

« Reply #6 on: 17 / September / 2016, 18:23:44 »

AFAIK, ML developers use color matrix from dcraw source...

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waterwingz

12140

Re: Help on camera color profile

« Reply #7 on: 17 / September / 2016, 19:39:16 »

Quote from: Ant on 17 / September / 2016, 18:23:44

AFAIK, ML developers use color matrix from dcraw source...

Which in turn, David Coffin (the man and initials behind dcraw) gets through user submission of a RAW image of a calibrated color target. AFAIK that is.

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Ported : A1200 SD940 G10 Powershot N G16