M9 file size?

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hlockwood

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Being a film shooter, quite ignorant of digital cameras, who is increasingly interested in the M9, I have some questions, many of which will be answered here over time.

But here's one that has me stymied. When I scan a color negative at 4000 ppi with my Nikon 4000ED, I get a 16-bit file size of about 135 MB. I can do the arithmetic for the ~21 Mpixels, 2 B/p, 3 colors and come up with a file size in agreement with that number.

The uncompressed RAW file for the (18.5 Mp) M9 is 36 MB. Will someone explain where all the MBs have gone? Is this not a 16-bit (2 B) file? Or is it that I don't understand RAW files (a distinct possibility)?

Harry
 
My D700 gives me approx. 15mb file size in RAW, converted to an 8 bit RGB TIFF file it works out to about 72mb (about 14"x20" @300dpi).

Convert that RAW file to a TIFF and see what you get.
 
The TIFF file size depends somewhat on the content, but a 36 Mb DNG expands to a TIFF that is considerably larger than 100Mb. It depends on the way the DNG is written. For instance on the M8 the 10.3 Mb DNG expands to about 50 Mb TFF, but if one runs a D-lux4 10 Mb RAW file through Adobe's DNG converter, it ends up as an approx 50 Mb DNG file.
 
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A RAW file is not demosaiced. It stores one value per pixel, and of these pixels 50% are green, 25% blue and 25% red (for a standard Bayer pattern). A TIFF file is demosaiced and the color information interpolated, so now we got three values per pixel, one for the red channel, one for the green, and one for the blue. So for the same number of megapixels, a TIFF wil be roughly 3 times the size of a RAW file (assuming no compression has been applied to either).
 
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ndnik said:
A RAW file is not demosaiced. It stores one value per pixel, and of these pixels 50% are green, 25% blue and 25% red (for a standard Bayer pattern). A TIFF file is demosaiced and the color information interpolated, so now we got three values per pixel, one for the red channel, one for the green, and one for the blue. So for the same number of megapixels, a TIFF wil be roughly 3 times the size of a RAW file (assuming no compression has been applied to either).
Click to expand...

That does indeed explain the arithmetic. Thanks very much.

Harry
 
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