Region of Image

Is it possible to develop a region of the image. For example the image is 1000x1000 pixels in size but I want a rectangle of pixels 100x100 at the position x = 200, y = 300.
Sorry in advance, if I missed the answer in the documentation.

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Current LibRaw postprocessing

Current LibRaw postprocessing routines (derived from dcraw) can only develop entire image area.

You may use unpack() to load entire Bayer pixels, than do demosaic/etc itself

-- Alex Tutubalin