Where is the 27 MB NEF files?
there are one unanswered question in my mind disturbing me for some time about the D100 NEF (uncompressed) file size: I learned it is similar to the TIFF files, includes EXIF info, plus a thumbnail and the raw data "directly from the CCD 12 bit per channel A/D converter", all in a 9.4 MB file.
My attention was awaked when I saw TIFF files at same resolution with 17.3 MB. That TIFF files uses 8 bit sample per channel (and NEF 12 bits).
Please correct my arithmetic if I am wrong:
3,008 pixels by 2,000 pixels = 6,016,000 effective pixels
6,016,000 pixels times 36 bits (12 bits per color) = 216,576,000 bits
216,576,000 bits = 27,072,000 BYTES, only for the "uncompressed raw image"
...plus EXIF and thumbnail data, I would expect 27 MB per uncompressed NEF - but it have only one third of this! Where is the fault? Is there any compression scheme for "uncompressed raw data"? Where is the "missing" information?
I would appreciate any input.
O.Cristo - An amateur photo clicker
O.Cristo - An Amateur Photographer
Opinions of men are almost as various as their faces - so many men so many minds. Franklin
#1. "RE: Where is the 27 MB NEF files?" | In response to Reply # 0AlanC Basic MemberThu 19-Sep-02 09:15 AM
A bit of background first: the individual pixels of the CCD measure the intensity of the light falling on them, but they're not sensitive to the wavelength so the CCD is, effectively, a monochrome device. To get a colour image an array of red, green and blue filters are placed in front of the pixels so each pixel responds to one primary colour only, and interpolation using the values of neighbouring pixels of the appropriate colour is used to determine the intensity of the two missing colours.
This is why RAW files are a third of the size you're expecting: each pixel is recording 12 bits of intensity but only for one of the primary colours - whereas a pixel in a TIFF file has values for each of the primary colours.