12bit versus 14bit - another sample test

Started Jun 6, 2008 | Discussions thread
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David314 Veteran Member • Posts: 4,790
12bit versus 14bit - another sample test

i took some software code that i had written several years ago to decode the raw files from a Fuji F700 and altered it to read the D300 raw uncompressed 14 bit files

with this i was able to read linear sensor data with no interpolation -this is truly raw

i will post some snippets of this code in the following post

this code is an outgrowth from dcraw of that vintage - with a uniformly exposed towel i can see no difference between 12 bits and 14 bits in detail or noise but.....

take this picture shot raw 14bit uncompressed D300 shown here full size

now things get interesting

question 1 - can you see a difference between 12bit and 14bit - remember this is a 12 bit file with just the 2 LSB's truncated and the answer is yes

question 2 - can you seen any detail in the window with just the LSB's and the answer is no

here is a screen shot compare the lower left hand corner 14bit with the 6LSB's and the upper right hand corner with 12 bit with the least 4 LSB's

this is a white uniform region just below the windowsill - notice the 14bit less coarse noise

also note the lower right hand corner which shows simply noise in the bright region

and final question - is there any image data int he 2LSB's of the 14bit data file

the answer is yes, in the very darkest parts of the picture -

this is the 2 LSB's of the 14bit data - nothing else and shifted in the program into a 16 bit value for import into photoshop

note these are all the same image with the output manipulated by software

so to sum it up - it appears that 14bit does capture some detail and does produce a different noise pattern (less grain) but only in the darkest parts of the image

good shooting!


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