The latest version of CDRaw has a -D switch, which causes totally raw output with no scaling. There is no demosaicing and the output is gray scale 0..4095. If you want RGB output, the above switches with -o 0 should do the trick.
Bill,
thanks for your explanations. Meanwhile, I did some testing an reading of your postings in the Adobe Forum. You say, you use the following options:
-m -n
So, in one case, we agree, since -m is equal to -o 0. See
here, and testing prooves this true.
But in the other case, I think your conversion is faulty. The one reason is obvious:
-n is equal to -H 1, which means, that clipped channels are filled with shades of pink, which is not usefull when evaluating highlights. As long as you have no clipped channels in you selection - no problemo. But I don't like that.
For the other reason, I have to go further into detail. It's all about the multipliers. If you set the option -v, you'll see a line like this during conversion:
Scaling with black=0, pre_mul[] = 2.270731 1.000000 1.273082 1.000000
In lack of a documentation from Dave Coffin, I interpret those values as the multipliers of the
direct values to the sensor data, seen as a square crop containing four pixels:
R G B G
My emphasis is on
direct, so if you are out for the unbiased sensor data, you'll have to use the option set
-r 1 1 1 1
If you use the -i option, some data of the image file is listed. At the bottom, there are two interesting lines:
Daylight multipliers: 2.094750 0.922500 1.174418
Camera multipliers: 271.000000 256.000000 751.000000 256.000000
These are the values from a Raw file of a Konica Minolta A2.
The first line defines the multipliers for the R G B values, which are supposed to balance the colors with daylight. dcraw sets the smallest value to 1 and adjusts the other colors. This multiplier set is used, if you convert without any (relevant) options set. The computed multipliers displayed are the above mentioned:
0.922500 scaled to 1.000000 (G)
2.094750 : 0.922500 = 2.270731 for R and
1.174418 : 0.922500 = 1.273082 for B
In the second line, you find the values for R G B G according to the set WB. It's the same scheme as above:
256.000000 scaled to 1.000000
271 : 256 = 1.058594
751 : 256 = 2.933594 (pretty extreme value, AWB at tungsten)
Exactly those values, you'll see if using the -w option (Use the color balance specified by the camera).
No, you are using the -n option, which gives the following multipliers:
1.000000 0.440387 0.560648 0.440387
This is a remarkable notation, since usually, the smallest value is set to 1.000000. So even if you type an option like this:
-r 0.5 1 1 1
it's converted to this form:
1.000000 2.000000 2.000000 2.000000
If you set the smallest multiplier (0.440387) to 1, you'll see that the ratio is the same as with the
daylight multipliers (edited). But now he sets the channel with the highest multiplier to one.
Anyway, you see, that using the -n option leads to false R G B values in the image, in the meaning of not as they were recorded. If you want all channels exactly as they were recorded by the sensor, you'll have to use the
-r 1 1 1 1
option, which BTW overrides the -n option.
The output is scaled by a factor of 16 to convert from 0..4095 (12 bit) to 0..65535 for display at 16 bits. The 12 bit output is very dark in Photoshop 15+1 display (0..32768).
Oh, yes, thanks for this hint. I was confused, since the values shifted considerably due to the sRGB conversion. The -o 0 or -m otpion solved the problem.
To sum it up, I recommend the following set for linear unbiased conversion:
dcraw.exe -3 -m -r 1 1 1 1 {file name}Any comments?