If I convert to DNG raw files (CR2) that were previously processed (via ACR) to grayscale, the resulting DNG has not an jpg preview embedded.
But if I do de same with not processed raw files, or files that where processed in color, no problem, the DNG files have jpg previews.
DNG converter 188.8.131.52
The same happens if I convert with Lightroom (3.5) or ACR (6.5).
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