Bit depth of raw files? - RAW Shooting and Processing - CHDK Forum
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Bit depth of raw files?

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Offline Treetop

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Bit depth of raw files?
« on: 25 / May / 2008, 19:42:20 »
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How can the bit depth of a raw file be found?  For example, does the SD850 have 10 or 12 bit (or more, unlikely) colour depth?   Maybe one of the RAW converters also shows file structure information.
Andy
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Offline BB

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Re: Bit depth of raw files?
« Reply #1 on: 25 / May / 2008, 20:29:33 »
If you read "C", Dave Coffin has his entire "C" source code right on his home page for DCRAW (can open just about any commercial RAW camera file out there--including CHDK's):

Decoding raw digital photos in Linux

C source:

http://www.cybercom.net/~dcoffin/dcraw/dcraw.c

From what I have read, the Canon P&S cameras have an effective depth of 10bits because of limitations in the A to D converters in the small sensors. And a good dSLR is around 12 to 13 (maybe 14) bits?

-Bill

PS: Here is a short interview of Dave Coffin about his history with DCRAW (note--don't layoff software developers--it gives them too much free time  :o ).  :D
« Last Edit: 25 / May / 2008, 23:49:06 by BB »
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Offline Treetop

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Re: Bit depth of raw files?
« Reply #2 on: 25 / May / 2008, 23:40:24 »
Thanks Bill; I'll have a look in the code.  There is probably some location where I can find and print the largest and smallest  pixel values found.
I had looked at the raw file itself but that didn't show clear patterns.
Andy
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Offline BB

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Re: Bit depth of raw files?
« Reply #3 on: 28 / May / 2008, 15:57:19 »
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Offline yg2007

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Re: Bit depth of raw files?
« Reply #4 on: 05 / July / 2008, 12:10:29 »
what about the G9 RAW, is it 10 or 12bit ?
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Offline user1

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Re: Bit depth of raw files?
« Reply #5 on: 05 / July / 2008, 12:31:08 »
At least, in some PowerShot cameras Canon uses 12-bit ADC, but 2 lowest data bits are unconnected.
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Offline cyril42e

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Re: Bit depth of raw files?
« Reply #6 on: 06 / July / 2008, 00:51:55 »
Where did you find this circuit diagram?? Did you break in Canon's?!  :D
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Offline dzsemx

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Re: Bit depth of raw files?
« Reply #7 on: 06 / July / 2008, 01:38:09 »
@user1: if you got more informations about the cameras, you could help a lot :)
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Offline Treetop

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Re: Bit depth of raw files?
« Reply #8 on: 07 / July / 2008, 00:05:22 »
User1 - would your info show what kind of USB interface is used on the camera?  It's low probability, but there might be a way to toggle the USB data lines and therefore use that as a signal output from the camera.  I can look through the data sheets (if it's a commercial part) to see if that might work.

Doing this would probably make the USB non-functional until the next power cycle which would be an OK drawback, but this would allow the MD script to trigger another camera (a DSLR) for instance.

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Offline octagonx

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Re: Bit depth of raw files?
« Reply #9 on: 27 / July / 2008, 11:51:06 »
hmm.. i don't think its possible to know something about how the chdk crw is written by looking at dcraw.c... impossible (for me).  I want to know, how are crw files written? in what format?
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