Eric Stevens wrote:
On Sun, 31 May 2009 16:11:00 -0800, (Floyd L.
Davidson) set out to change the substance of the discussion by
massively editing the article to which he is responding. He is alos
trying to switch the argument from the relationship of the original
image to the RAW file to the relationship of the original image to the
raw data (which is quite different from the content of the RAW file).
You actually are that dense!
Exactly. So why are you claiming otherwise? The raw
data set is not changed. But there are multiple,
correct, different sets of rules used to generate an
exact image from the raw data.
I've been talking about the RAW file from the beginning. So too were
you at that time. Remember "Floyd, I suspect you have been smoking
something which is not good for you. Subject to statistical error
limitations, ... The data in the RAW file can't be restructured to
make a different image without changing the data."
The data in the raw file is not restructured.
Your nonsense is still nonsense.
The sensor locations are hardly irrelevant either. As I
said, at least *nine* of them are used to generate each
pixel in the resulting image, and you can be assured the
location is relevant! It isn't one pixel and then 8
other randomly chosen locations... it's a group of 9
(or more).
So?
So please cease this silliness where you claim the
sensor locations are irrelevant.
For any one camera, its just one of the items which go to the
transformation of the image to the RAW file. The sensor locations are
invariant as is the other camera hardware, and the firmware for that
matter.
So what are you trying to say? The sensor locations *are*
relevant!
You do understand that "firmware" is where the
"software" is, right?
I'm getting the idea that you have a list of buzz words; but no
idea what any of it means.
The signals generated by the sensors are determined by the
rules inherent in the camera's software.
That statement is blatantly false.
They are determined by rules inherent in the camera's
hardware. The sensor is not manipulated by software
other than clearing it and reading it. A given amount
of light on one sensor locations produces *exactly* the
same output from the sensor regardless of the camera's
software.
I should have said "The signals generated by the sensors are
-interpreted- by the rules inherent in the camera's software". To that
extent they are 'determined'.
This statement is blatantly *different*.
I quoted you exactly above. Now you want to change what
you said.
Its called clarification. I haven't changed the meaning.
They you don't understand what you said.
Regardless, you are still wrong. The signals from the
sensor are interpreted according to *hardware* and the
resulting data set is written to a RAW file format.
That is what is "interpreted" by software.
Have I ever said otherwise? But so what?
You did say otherwise. Quoted above.
So you now admit that it is not software at all, but a
hard wired hardware transform.
I don't see why you should suddenly try to make that point. In any
case, while I don't know about your camera, I can download an update
for mine. That doesn't sound as though it is all hardware to me.
You aren't going to download an update that changes how the
hardware processes sensor data to generate the "raw data". It's
hard wired. The sensor output is *analog*, and the digital
data is generated by a series of *hardware* devices. About all
the software does is switch the hardware on and off!
I assumed a certain level of technical competence from your
background.
That is correct. A few decades working with digital data,
transmission systems (which is what the hardware between the
sensor and the CF card is) and little things like that... :-)
I wouldn't argue with you over what you have just said but I would
like to point out that this discussion has been about the interpolated
data saved in the RAW file.
The raw data saved in the RAW file is not interpolated.
The raw data does not define one specific image. When
the data is interpolated there is then an image!
And when that data is interpolated and saved in a RAW file then there
That does not happen. (Except of course for the various
thumbnail JPEG images that are embedded in most RAW files.)
is only the one image. Run that RAW file backwards through the same
transformation and you end back up with the original image of which
there can only be the one.
It is a one way process and it cannot be precisely
reversed. If for no other reason than what is called
quantization distortion... However, in addition to that
the JPEG image which results from interpolation simply
does not contain anything like the full amount of
information that was in the RAW file's data. You cannot
reverse the process.
--
Floyd L. Davidson http://www.apaflo.com/floyd_davidson
Ukpeagvik (Barrow, Alaska)