Myślę, że marfot wiele wyjaśnił w tym temacie.

Jeszcze tutaj wyjaśnienie dlaczego rośnie rozmiar plików ze strony zaproponowanej przez marfota:
"The SRAW image is in a hybrid format; it is not truly raw any more. It is raw only in the sense, that the colors are in the camera's color space and WB has not been applied yet, but otherwise it has nothing common with the original raw format. It is demosaiced, i.e. the pixels have three color components. However, not each pixel has three separate color component: adjacent pixel pairs are sharing two of the three color components.

This format is Canon specific, DNG does not know such format. The nearest format in DNG is the "linear" image, which is demosaiced and each pixel has its own three color components. Thus the amount of data is much more in the DNG linear format than in the sRaw format. Of course, this does not represent any enhancement of the image quality, the DNG converter can not really add to the image content.
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Dziękuję bardzo za odpowiedź i również tym samym zaprzestaję korzystania z sRAWów