Hi, I know basically nothing about DNG, but Googling suggests that yes, the planes are probably referring the different color channels. There's a tag CFAPlaneColor that sets which order the colors map to the planes or else they're RGB.
Chromatic aberration is essentially when the different colours are distorted differently, so my first guess is that you should calculate the distortion from the average of the planes. Then the difference between the planes should be encoded in the TCA parameters. Alternatively, since the TCA parameters are given for R and B, perhaps it would work better to take the distortion only from the G plane, I'm not sure. I haven't tried to work out how the TCA parameters would be derived. If the method looks like it's working then I can probably have a look and see if the calculation is simple enough, or else it should be simple enough to write a script to find the values that match the warp from the dng file. I don't think lensfun encodes the optical centre from the warp (so it would have to be set to 0.5, 0.5). I'm not sure how much that would affect the accuracy of the data. It's also worth noting that the DNG file uses different coordinates for pixels (0,0 in the corner) than lensfun (0,0 in the centre). Hope that helps. I'm interested to know how you get on with converting the information. Thanks, Graeme On Wed, 17 Nov 2021, 13:05 Gunar Kachel, <gunar.kac...@gmail.com> wrote: > Hi, my lens is not yet supported by lensfun. I therefore searched for a > method to to get the right distortion and chromatic aberration profile to > be used in daktable. (And I was not very successful applying the "manual" > method using Hugin.) > > However, as this is a modern lens the profiles are already integrated in > the RAW file and I therefore followed this procedure: > > 1. convert the RAW file (NEF) to DNG using Adobe DNG Converter > 2. extract OpCoodeList3 parameters from DNG file using > dng-validate.exe (at the bottom) > > > I assume I can implement these values using the lensfun distortion profile > model "acm". > However I'm puzzled that values are provided in several "planes". > Are the planes referring to different color channels? > How to implement the planes in lensfun? > How can I cover chromatic aberration using these information? > > Thanks in advance for the insight! > > Sample output from dng-validate.exe -v: > >>>>>>>>>>>>>>>> > Opcode: WarpRectilinear, minVersion = 1.3.0.0, flags = 0 > Planes: 3 > Optical center: > h = 0.501405 > v = 0.504913 > Plane 0: > Radial params: 1.025498, -0.124349, 0.058447, -0.003755 > Tangential params: 0.000000, 0.000000 > Plane 1: > Radial params: 1.025181, -0.124368, 0.058438, -0.003759 > Tangential params: 0.000000, 0.000000 > Plane 2: > Radial params: 1.025277, -0.124355, 0.058413, -0.003751 > Tangential params: 0.000000, 0.000000 > <<<<<<<<<<<<<<<<< > _______________________________________________ > Lensfun-users mailing list > Lensfun-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/lensfun-users >
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