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Question about "raw" and in-camera image processing

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Anonymous
June 23, 2005 5:16:23 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

I've noticed different "looks" to pictures in
tests done on various DSLRs. Not just the result
of pixel count differences (there may be none, say,
between the Olympus E-300 and Canon Rebel XT)
but because of what is happening to the image
once it's aquired. What I'd like to know is,
which cameras seem to have the most agressive
image processing firmware and is this applied
to raw files? I know that some cameras have a selectable
noise reduction feature, I wasn't really interested
in it's effect, so the question pertains to cameras
with that feature turned off.
Anonymous
June 23, 2005 5:43:49 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

RichA wrote:

> So the raw file's composition is determined solely
> by the sensor itself?

Even a brief perusal of a grep at google will tell you as much.

You just babbling because you are lonely or something?
Anonymous
June 23, 2005 6:02:44 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

On Thu, 23 Jun 2005 13:16:23 -0400, in rec.photo.digital.slr-systems RichA
<none@none.com> wrote:

> and is this applied
>to raw files?

No. That's what RAW means.
----------
Ed Ruf Lifetime AMA# 344007 (Usenet@EdwardG.Ruf.com)
See images taken with my CP-990/5700 & D70 at
http://edwardgruf.com/Digital_Photography/General/index...
Related resources
Anonymous
June 23, 2005 8:04:19 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

On Thu, 23 Jun 2005 14:02:44 -0400, Ed Ruf <egruf_usenet@cox.net>
wrote:

>On Thu, 23 Jun 2005 13:16:23 -0400, in rec.photo.digital.slr-systems RichA
><none@none.com> wrote:
>
>> and is this applied
>>to raw files?
>
>No. That's what RAW means.

So the raw file's composition is determined solely
by the sensor itself?
June 24, 2005 4:21:33 AM

Archived from groups: rec.photo.digital.slr-systems (More info?)

Ed Ruf wrote:

> On Thu, 23 Jun 2005 13:16:23 -0400, in rec.photo.digital.slr-systems RichA
> <none@none.com> wrote:
>
>> and is this applied
>>to raw files?
>
> No. That's what RAW means.
>

I've read that the cmos sensors are doing noise reduction at the sensor
level so there is at least some processing going on with a cmos camera even
if you believe there is -zero- processing on the RAW file. Of course I
believe there is no contrast or sharpening, WB etc going on but I wouldn't
be shocked to find that some image processing is being done even to a "RAW"
file before the RAW data is written to the card. SInce almost every camera
has it's own RAW file format, there must be some sort of processing done to
even generate the file?
--

Stacey
Anonymous
June 24, 2005 8:11:33 AM

Archived from groups: rec.photo.digital.slr-systems (More info?)

Stacey wrote:
> Ed Ruf wrote:
> > On Thu, 23 Jun 2005 13:16:23 -0400, in rec.photo.digital.slr-systems RichA
> > <none@none.com> wrote:
> >
> >> and is this applied
> >>to raw files?
> >
> > No. That's what RAW means.
>
> I've read that the cmos sensors are doing noise reduction at the sensor
> level so there is at least some processing going on with a cmos camera even
> if you believe there is -zero- processing on the RAW file. Of course I
> believe there is no contrast or sharpening, WB etc going on but I wouldn't
> be shocked to find that some image processing is being done even to a "RAW"
> file before the RAW data is written to the card. SInce almost every camera
> has it's own RAW file format, there must be some sort of processing done to
> even generate the file?

There is processing, of course, but the question is whether it changes
the Raw sensor data. But ....

First, of course, there has to be processing even to obtain what we
think of as the Raw sensor data. Sensors deliver electrons, and cameras
do not just store a count of electrons into the Raw file. So they must
have an algorithm for converting the count of electrons, or amount of
charge, into the numbers held in the Raw file or used for further
processing.

Second, I have seen a suggestion that the Nikon D70 does further
processing in order to compress the sensor data further. I think this
is the only case of lossy compression of sensor data I've read about,
and I have no independent evidence for this statement:

"The Compressed NEF format is the only one that comes close to
retaining the full data set the D70 is capable of acquiring. I say
"close to retaining" because the compression scheme Nikon uses is not
lossless. Basically, the camera takes the highlight data and places
them into groups (essentially a rounding of many of the data points),
producing the equivalent to somewhere between 9 and 10 bits of data.
When this is returned to 12-bit form, there's a bit of posterization in
the highlight data. The reason this works as a visually lossless scheme
is that our eyes really can't resolve more than about an 8-bit value
can produce (and our eyes aren't linear in response to light, either).
For the most part it isn't a big thing that the compression loses data,
though there may be some post-processing manipulations that will render
slightly differently because of the data rounding."

http://www.bythom.com/D70REVIEW.HTM

Third, generating the file itself is not really an issue. A Raw file is
a container, and generating the tags or whatever of the container
doesn't itself mean that the sensor data is being changed.

None of the above is about any type of processing that uses data from
more than one pixel (or "sensel"?) at a time. (Sharpening, noise
reduction, etc). I think that is what people are normally talking about
when they distinguish between Raw and other formats.

--
Barry Pearson
http://www.barry.pearson.name/photography/
http://www.birdsandanimals.info/
June 24, 2005 10:19:57 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

Barry Pearson wrote:


>
> None of the above is about any type of processing that uses data from
> more than one pixel (or "sensel"?) at a time. (Sharpening, noise
> reduction, etc). I think that is what people are normally talking about
> when they distinguish between Raw and other formats.
>


But how would we ever really know if this is the case? They could easily
"slip" some processing in that you'd never know they had done. Not that we
could ever do anything about it or that it even really matters but just
because it's "RAW" doesn't mean it's just a sensor dump straight to the
card either.

--

Stacey
Anonymous
June 25, 2005 5:30:33 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

In message <3i3f8dFj9uvnU2@individual.net>,
Stacey <fotocord@yahoo.com> wrote:

>But how would we ever really know if this is the case? They could easily
>"slip" some processing in that you'd never know they had done. Not that we
>could ever do anything about it or that it even really matters but just
>because it's "RAW" doesn't mean it's just a sensor dump straight to the
>card either.

There's no such thing as a straight dump of analog data into binary
data.
--

<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
John P Sheehy <JPS@no.komm>
><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
June 25, 2005 6:20:55 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

JPS@no.komm wrote:

> In message <3i3f8dFj9uvnU2@individual.net>,
> Stacey <fotocord@yahoo.com> wrote:
>
>>But how would we ever really know if this is the case? They could easily
>>"slip" some processing in that you'd never know they had done. Not that we
>>could ever do anything about it or that it even really matters but just
>>because it's "RAW" doesn't mean it's just a sensor dump straight to the
>>card either.
>
> There's no such thing as a straight dump of analog data into binary
> data.

Yet people "believe" that's what RAW data is and there is no posibility
that it has been processed by the camera. Seems obvious to me Ed Ruf
believes this from his coment "No. That's what RAW means." when the
question of extra processing was brought up.
--

Stacey
Anonymous
June 25, 2005 6:46:33 PM

Archived from groups: rec.photo.digital.slr-systems (More info?)

On Sat, 25 Jun 2005 14:20:55 -0400, in rec.photo.digital.slr-systems Stacey
<fotocord@yahoo.com> wrote:

> Yet people "believe" that's what RAW data is and there is no posibility
>that it has been processed by the camera. Seems obvious to me Ed Ruf
>believes this from his coment "No. That's what RAW means." when the
>question of extra processing was brought up.

You can believe what you like.
IF you reread the OP
On Thu, 23 Jun 2005 13:16:23 -0400, in rec.photo.digital.slr-systems RichA
<none@none.com> wrote:

>I've noticed different "looks" to pictures in
>tests done on various DSLRs. Not just the result
>of pixel count differences (there may be none, say,
>between the Olympus E-300 and Canon Rebel XT)
>but because of what is happening to the image
>once it's aquired. What I'd like to know is,
>which cameras seem to have the most agressive
>image processing firmware and is this applied
>to raw files? I know that some cameras have a selectable
>noise reduction feature, I wasn't really interested
>in it's effect, so the question pertains to cameras
>with that feature turned off.

You may see that one can interpret in another way. Given the emphasis by
the OP on "aggressive image processing firmware" and "tests done on various
DSLRs", I took this to be inquiring about the many comparison images in
sites such as dpreview which are comparisons of JPGs produced by the
camera. These are affected by the default in camera processing in such
areas as sharpening, contrast and saturation. My reply was stating THESE
in camera adjustments have no effect on the raw images.
----------
Ed Ruf Lifetime AMA# 344007 (Usenet@EdwardG.Ruf.com)
See images taken with my CP-990/5700 & D70 at
http://edwardgruf.com/Digital_Photography/General/index...
Anonymous
July 7, 2005 8:21:43 AM

Archived from groups: rec.photo.digital.slr-systems (More info?)

Stacey wrote:
> Ed Ruf wrote:
>
>
>>On Thu, 23 Jun 2005 13:16:23 -0400, in rec.photo.digital.slr-systems RichA
>><none@none.com> wrote:
>>
>>
>>>and is this applied
>>>to raw files?
>>
>>No. That's what RAW means.
>>
>
>
> I've read that the cmos sensors are doing noise reduction at the sensor
> level so there is at least some processing going on with a cmos camera even
> if you believe there is -zero- processing on the RAW file. Of course I
> believe there is no contrast or sharpening, WB etc going on but I wouldn't
> be shocked to find that some image processing is being done even to a "RAW"
> file before the RAW data is written to the card. SInce almost every camera
> has it's own RAW file format, there must be some sort of processing done to
> even generate the file?


So what? Each cell is doing the subtraction from it's own ambient noise
level to get the signal value. How do you see this as an image
enhancement? [I assume your refer processing as noise
reduction/enhancement.] And do you know how much is the noise floor
level of your CCD? How about the noise generated by the amplifier used
to capture the signal from the CCD? If you don't like CMOS, then don't
dream of D2X.
!