or if you plan to act like DxO (raw -> DxO (corrections) -> linear DNG -> ACR/LR to deal w/ WB and some colors) then you have to be a good in demosaicing first of all... so why don't you just write a fully functional raw converter ?
Short answer: I don't want to spend a bunch of time reinventing the wheel when there are many very good RAW converters already out there. OTOH, DXO doesn't really have a lot of competition for really good lens corrections, it's way overpriced, and it's crippled because you are locked into using "canned" blur profiles for cameras and lenses, and if DXO doesn't have profiles for your camera or lens, you're screwed--you can't use it.
If your lens' blur characteristics differ from the DXO-profiled lens, then the "canned" profiles aren't going to work all that well anyway. If a printer manufacturer only allowed the use of their canned print profiles, and didn't allow users to make their own profiles, they'd be laughed out of the market. But that is essentially DXO's business model.
it looks like your software is running before any raw converter, otherwise why bother to output into linear DNG ?
The corrections I'm doing need to be done after demosaic. The deconvolution algorithm I'm working on analyzes a linear RGB image of an array of circular light sources (ideally about 5-10 pixels in diameter in the RAW image) and analyzes the blur characteristics found. The blur in the demosaiced image is a combination of lens blur, AA filter blur, and blur introduced by the demosaic algorithm of the RAW converter. By analyzing the total blur caused by all elements of the image capture process (lens, camera, and RAW converter) all of the blur from every blur source can be removed at once.
The basic workflow is this:
1. Run DNG Converter to convert RAWs to linear-RGB DNG files. Essentially all this does is fills in the missing color channel values from the Bayer matrix (e.g. adds R & B values to a G pixel), and then scales the values 0-65535. This can be done on a batch of files.
2. Process the DNGs through my program to correct lens, AA filter, and demosaic blur, remove CA/color fringing, correct fisheye/barrel/pincushion/mustache distortion, eliminate vignetting, etc., and eventually stack multiple focus and/or exposure-bracketed images into a single output DNG. This can be a batch process also.
3. Open the processed DNGs and edit as desired.
The RGB data is still in the camera's native color space, so you still have total flexibility to set white balance, adjust exposure, process colors, etc. the same as with the original RAW, as long as the RAW converter you use can read DNGs. Using my program will require an extra step in the workflow, but my goal is to make the benefits greatly outweigh the slight inconvenience.