by bengelenburg on Fri Feb 10, 2012 1:28 pm
Hi,
The whole issue wit DNG for Corel/Bibble is caused by the complexity of DNG and the lack of features in the first releases of DNG. This probably has improved over time but still withholds me from using DNG and and I think also withholds Corel from incorporating converted DNG support into their ASP product.
As far as I understand it now (please correct me if I am wrong) when raw files are converted to DNG with default settings , raw sensor data is transferred into Linear DNG. You get from the raw sensor data (1 RGB value per photocel) to linear DNG (3 RGB values per photocel) by a proces called Demosaicing which the Adobe DNG converter does for you. You can tell the DNG converter to not produce linear DNG but that is an option you have to have specified while converting, even then the raw format is transferred to a file format called TIFF/EP. In Tiff/EP different Tags are used to describe the raw sensor data then in the original (Exif/DCF). Of course DNG offers the possibility to include the original raw file , and it claims that the raw file can be restored to the original. I have never tried so i am not convinced, even space programs fail due to software bugs. You can only loose your data once.
If you choose to use linear DNG you have handed over the demosaicing process to Adobe and denied yourself the opportunity to take advantage of scientific progress in the development of alternative demosaicing algorithms.
Tools like ASP, Aperture , ACDSEE Pro have their own demosaicing algorithm which as a raw developing tool is their main functionality. However it does not makes sense for them to write DNG, due to the different tag structure and raw linear produced these DNG would not display very well in Photoshop or PSP. ( they would not recognise the tags.
Reading a a non linear DNG would mean that due to the different tag/file structure an additional camera profile needs to be used for each camera ( multiplying all camera profiles and the amount of work associated with it). Reading a linear DNG would/could be possible,but like with jpeg and tiffs you would only have a limited amount of the editing functionality in ASP available, for example white balance correction is ( I think) part of the demosaicing.
Of course if you have included the original raw in the DNG, ASP could use that but then with all those options the processing of DNG in ASP would be immensely complex.
Basically for tools like PSP support of DNG is easier because they work on linear instead of raw data and still they numerous issues with it.
Regards
Bert