Adding camera profile correction to dng_validate.exe [Adobe DNG SDK]

Using Lightroom I know how to apply a camera profile (*.dcp file) to my *.DNG image.

I would like to do the same in an application which I'm writing, so I guess a good starting point would be to append this functionality to the dng_validate.exe application.

So I started to add:

#include "dng_camera_profile.h"

Then added:

static dng_string gDumpDCP; 

And add the following to the error print:

"-dcp <file>   Load camera profile from <file>.dcp\"\n"

Then I added the function to read the dcp from cli:

else if (option.Matches("dcp", true))
{
   gDumpDCP.Clear();
   if (index + 1 < argc)
   {
      gDumpDCP.Set(argv[++index]);
   }

   if (gDumpDCP.IsEmpty() || gDumpDCP.StartsWith("-"))
   {
      fprintf(stderr, "*** Missing file name after -dcp\n");
      return 1;
   }

   if (!gDumpDCP.EndsWith(".dcp"))
   {
      gDumpDCP.Append(".dcp");
   }

}

Then I load the profile from disk [line 421]:

if (gDumpTIF.NotEmpty ())
{
   dng_camera_profile profile;
   if (gDumpDCP.NotEmpty())
   {
      dng_file_stream inStream(gDumpDCP.Get());
      profile.ParseExtended(inStream);
   }
   // Render final image.
   .... rest of code as it was

So how do I now use the profile data to correct the render and write the corrected image?

So after playing around for a couple of days, I now found the solution. Actually the negative can have multiple camera profiles. So with negative->AddProfile(profile) you just add one. But this won't be used if it's not the first profile! So we first need to clean the profiles and than add one.

AutoPtr<dng_camera_profile> profile(new dng_camera_profile);
if (gDumpDCP.NotEmpty())
{
    negative->ClearProfiles();
    dng_file_stream inStream(gDumpDCP.Get());
    profile->ParseExtended(inStream);

    profile->SetWasReadFromDNG();
    negative->AddProfile(profile);

    printf("Profile count: \"%d\"\n", negative->ProfileCount()); // will be 1 now!
}

Next thing to get the image correctly is to have correct white balance. This can be done in camera or afterwards. For my application with 4 different cameras, the result was the best when using afterward white balance correction. So I found 4 (Temperature,Tint) pairs using Lightroom.

The question was how to add these values in the dng_validate.exe program. I did it like this:

#include "dng_temperature.h"

if (gTemp != NULL && gTint != NULL)
{
    dng_temperature temperature(gTemp, gTint);
    render.SetWhiteXY(temperature.Get_xy_coord());
}

The resulting images are slightly different from the Lightroom result, but close enough. Also the camera to camera differences are gone now! :)