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Could you actually see photos made from RAW files?



 
 
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  #1  
Old May 31st 09, 01:22 AM posted to rec.photo.digital,uk.rec.photo.misc
Floyd L. Davidson
external usenet poster
 
Posts: 5,138
Default Could you actually see photos made from RAW files?

wrote:
I am sorry if this topic may have been discussed too many times.
However, I still have difficulties dealing with the concept of RAW
files. Someone suggested that RAW files are like negatives, while-as
JPEG files are like prints.


Better analogies might make things clearer. You can buy
a house pre-built... that's like JPEG or a TIFF image.
Note that it not totally static, in that you can change
it with a coat of paint, you can add a window or a room,
etc etc. But basically all of those things are
additions (edits) to the original house (image).

You can also take a set of plans to the lumber yard and
have everything needed to make a house delivered to your
lot. It's boxes of nails, stacks of lumber and stacks
of paint and of this and stacks of that. You can follow
the original set of plans and make the house that was in
your mind when you looked at the plans, but you can also
use this same pile of parts to build an entirely
different house too. That's what a camera raw file (the
so called RAW format) is... a pile of parts that you
can build an image from, and while the photographer may
have had one specific image in mind when that pile of
data was saved, it can be restructured to make a lot of
different images too.

A JPEG or TIFF file contains an image. The RAW file
contains data to make an image.

For example, each "sensal" location on the sensor does
*not* translate to a single pixel in the resulting
image. Instead the data from at least 9 different
sensors locations is used to determine the Red, Green,
and Blue values for a single pixel.

The process where all of that data is interpolated is
called "raw conversion", and is much the same as
converting a pile of nails and boards into a house.

My question is whether we can physically see a RAW file... I mean


There is no house yet, so you can't walk up and knock on
the door or go inside!

The data has to be converted to an image before you can
"physically see" it.

without placing it in the mercy of a software to open it as a JPEG
file (and in the mean time, the software is doing the processing and
converting it into JPEG using their own algorithm to produce what they
consider to be the best JPEG. I agree that perhaps people should
create both RAW and JPEG files when they take pictures.


In fact almost all RAW file formats also include a JPEG
image generated by the camera (sort of a "model" of the
house). That can be a blessing (its quick to look at)
or a curse (it isn't necessarily a model of the house
you'll build).

The next question is whether commercial photo processing softwares
(Photoshop, Paintshop, Aperture, etc) treating RAW files produced from
different brand cameras differently, as I noticed that the extension
file name for RAW files differ from cameras to cameras. Can the
special software made by the camera's manufacturer (which sometimes
comes with the camera that you purchase) do a better job than the
commercially photo processing softwares?


Generally speaking, there isn't really much difference.
But specifically, if you are extremely critical you
might be able to see differences. But the biggest
problem is that it requires a good bit of skill to
adjust different software to produce exactly the same
final image, and many people judge the "default"
results. Each software package might, of course, have
vastly different defaults...

But in fact, for most images, any of the large number of
raw converters can be used to produce the exact same
image from the original raw data.

I recall that someone mentioned that the camera's processing engine is
not as versatile as a computer's photo processing software, as well as
the time to produce the JPEG file in the camera is relatively short.


Your PC has massively more compute power than the CPU in
the camera. Plus the camera has relatively course
granularity in making adjustments compared to what is
available with most computer programs. For example the
camera may give you a possibility of 10 values for
contrast adjustment, while a computer program may give
you 200.

The most obvious problem though is that you have to set
the camera *before* you have the data, and then you
can't change it. With post processing you get to see
what all of the possible images might be, not just one.

Post process is generally more productive than preprocessing.

Therefore, built-in camera processing engine cannot make a better job
than a real photo processing software. As processing speed is getting
faster and faster, could a camera sometime in the future produces JPEG
photos which are as good as or better than the commercial photo
softwares?


Sure... but also consider that while you are shooting
you'd have to take the same amount of time to make those
adjustments, except it would be between shots. Usually
it's just much easier to shoot RAW and get on with more
exposures while using the camera, and then later spend
the time necessary for adjustment of each image.

Again, it's post vs pre.

--
Floyd L. Davidson http://www.apaflo.com/floyd_davidson
Ukpeagvik (Barrow, Alaska)

  #2  
Old May 31st 09, 02:38 AM posted to rec.photo.digital,uk.rec.photo.misc
Steven Green[_3_]
external usenet poster
 
Posts: 11
Default Could you actually see photos made from RAW files?

wrote:
Thanks for the overwhelming replies. I appreciate this very much. I
also like the analogy of building a house vs. renovate the house.
Perhaps in the future I will try to keep both RAW and JPEG files,
particularly when taking photos for important events.

I do, however, wonder that by working on raw format, one will end up
spending much more time post processing after the photos are taken.
This sometimes I do not have the luxury to do it. Therefore, I also
look around with interest on what camera is doing better than the
others (in terms of generating JPEG photos), or at least the
processing that this particular camera is suit to your likings in
colour, contrast, tones, etc.

I just have one question - if you take a photo which was out of focus,
could you actually make it in focus when you have the raw files?

One more time, I thank you very much to all responders for the very
useful discussion on this topic!
Regards

The optics control what is in focus at the plane where the film or
sensor is. What you see in a jpeg is essentially the same you will see
in the raw. You have no more control of focus in a raw than in a jpeg
  #3  
Old May 31st 09, 03:06 AM posted to rec.photo.digital,uk.rec.photo.misc
Savageduck[_2_]
external usenet poster
 
Posts: 363
Default Could you actually see photos made from RAW files?

On 2009-05-30 18:24:19 -0700, said:

Thanks for the overwhelming replies. I appreciate this very much. I
also like the analogy of building a house vs. renovate the house.
Perhaps in the future I will try to keep both RAW and JPEG files,
particularly when taking photos for important events.


Always save the RAW files they are your "digital negatives" working
JPGs are the ultimately disposable files.

I do, however, wonder that by working on raw format, one will end up
spending much more time post processing after the photos are taken.
This sometimes I do not have the luxury to do it. Therefore, I also
look around with interest on what camera is doing better than the
others (in terms of generating JPEG photos), or at least the
processing that this particular camera is suit to your likings in
colour, contrast, tones, etc.


That is one of the reasons to shoot RAW + JPG. That way you can have
quick access to the JPGs and make adjustments to select RAW files as
you choose. ...but you can only do that if you have the RAW file. Just
remember, any incamera adjustments are not going to effect the RAW
files, only the JPGs. So if a JPG is turns out not to your liking, the
RAW should be there to bail you out.
Also, as you develop a work flow you are comfortable with you will find
working with RAW will become quicker & quicker.

I just have one question - if you take a photo which was out of focus,
could you actually make it in focus when you have the raw files?


No. The RAW file is the record of the image captured in its purest
form, and if it is out of focus that lack of focus is part of the
permanant data for that image.
There is only so much you can fix.

One more time, I thank you very much to all responders for the very
useful discussion on this topic!
Regards



--
Regards,
Savageduck

  #4  
Old May 31st 09, 04:01 AM posted to rec.photo.digital,uk.rec.photo.misc
nospam
external usenet poster
 
Posts: 24,165
Default Could you actually see photos made from RAW files?

In article
,
wrote:

I do, however, wonder that by working on raw format, one will end up
spending much more time post processing after the photos are taken.


that's absolutely false.

with modern raw converters, there is *no* time penalty for shooting
raw, unless of course, you want to spend a lot of time tweaking it.
quite often, the default parameters are good enough, with maybe only a
minor tweak needed.

with some raw converters (e.g., lightroom), there isn't even a
difference in the workflow between raw or jpeg - you just give it
images from the camera and see the results on screen, adjust as needed,
print or upload to the 'net. it's same amount of time either way, but
if you shoot raw, the results will generally be better than if you
shoot jpeg. that's why it's somewhat of a waste to shoot raw+jpeg.

I just have one question - if you take a photo which was out of focus,
could you actually make it in focus when you have the raw files?


not really. it can be possible to undo it a little with very
sophisticated modeling of the lens and a lot of expensive software
though.
  #5  
Old May 31st 09, 05:37 AM posted to rec.photo.digital,uk.rec.photo.misc
Eric Stevens
external usenet poster
 
Posts: 13,611
Default Could you actually see photos made from RAW files?

On Sat, 30 May 2009 16:22:03 -0800, (Floyd L.
Davidson) wrote:

wrote:
I am sorry if this topic may have been discussed too many times.
However, I still have difficulties dealing with the concept of RAW
files. Someone suggested that RAW files are like negatives, while-as
JPEG files are like prints.


Better analogies might make things clearer. You can buy
a house pre-built... that's like JPEG or a TIFF image.
Note that it not totally static, in that you can change
it with a coat of paint, you can add a window or a room,
etc etc. But basically all of those things are
additions (edits) to the original house (image).

You can also take a set of plans to the lumber yard and
have everything needed to make a house delivered to your
lot. It's boxes of nails, stacks of lumber and stacks
of paint and of this and stacks of that. You can follow
the original set of plans and make the house that was in
your mind when you looked at the plans, but you can also
use this same pile of parts to build an entirely
different house too. That's what a camera raw file (the
so called RAW format) is... a pile of parts that you
can build an image from, and while the photographer may
have had one specific image in mind when that pile of
data was saved, it can be restructured to make a lot of
different images too.


Floyd, I suspect you have been smoking something which is not good for
you. Subject to statistical error limitations, there is a one to one
correspondence between the source image and the RAW file. One can be
converted to the other using the rules inherent in the camera's
software. The data in the RAW file can't be restructured to make a
different image without changing the data.

A JPEG or TIFF file contains an image. The RAW file
contains data to make an image.

For example, each "sensal" location on the sensor does
*not* translate to a single pixel in the resulting
image. Instead the data from at least 9 different
sensors locations is used to determine the Red, Green,
and Blue values for a single pixel.

The process where all of that data is interpolated is
called "raw conversion", and is much the same as
converting a pile of nails and boards into a house.

My question is whether we can physically see a RAW file... I mean


There is no house yet, so you can't walk up and knock on
the door or go inside!

The data has to be converted to an image before you can
"physically see" it.

without placing it in the mercy of a software to open it as a JPEG
file (and in the mean time, the software is doing the processing and
converting it into JPEG using their own algorithm to produce what they
consider to be the best JPEG. I agree that perhaps people should
create both RAW and JPEG files when they take pictures.


In fact almost all RAW file formats also include a JPEG
image generated by the camera (sort of a "model" of the
house). That can be a blessing (its quick to look at)
or a curse (it isn't necessarily a model of the house
you'll build).

The next question is whether commercial photo processing softwares
(Photoshop, Paintshop, Aperture, etc) treating RAW files produced from
different brand cameras differently, as I noticed that the extension
file name for RAW files differ from cameras to cameras. Can the
special software made by the camera's manufacturer (which sometimes
comes with the camera that you purchase) do a better job than the
commercially photo processing softwares?


Generally speaking, there isn't really much difference.
But specifically, if you are extremely critical you
might be able to see differences. But the biggest
problem is that it requires a good bit of skill to
adjust different software to produce exactly the same
final image, and many people judge the "default"
results. Each software package might, of course, have
vastly different defaults...

But in fact, for most images, any of the large number of
raw converters can be used to produce the exact same
image from the original raw data.

I recall that someone mentioned that the camera's processing engine is
not as versatile as a computer's photo processing software, as well as
the time to produce the JPEG file in the camera is relatively short.


Your PC has massively more compute power than the CPU in
the camera. Plus the camera has relatively course
granularity in making adjustments compared to what is
available with most computer programs. For example the
camera may give you a possibility of 10 values for
contrast adjustment, while a computer program may give
you 200.

The most obvious problem though is that you have to set
the camera *before* you have the data, and then you
can't change it. With post processing you get to see
what all of the possible images might be, not just one.

Post process is generally more productive than preprocessing.

Therefore, built-in camera processing engine cannot make a better job
than a real photo processing software. As processing speed is getting
faster and faster, could a camera sometime in the future produces JPEG
photos which are as good as or better than the commercial photo
softwares?


Sure... but also consider that while you are shooting
you'd have to take the same amount of time to make those
adjustments, except it would be between shots. Usually
it's just much easier to shoot RAW and get on with more
exposures while using the camera, and then later spend
the time necessary for adjustment of each image.

Again, it's post vs pre.




Eric Stevens
  #6  
Old May 31st 09, 06:32 AM posted to rec.photo.digital,uk.rec.photo.misc
Floyd L. Davidson
external usenet poster
 
Posts: 5,138
Default Could you actually see photos made from RAW files?

Eric Stevens wrote:
Floyd, I suspect you have been smoking something which is not good for
you. Subject to statistical error limitations, there is a one to one
correspondence between the source image and the RAW file. One can be
converted to the other using the rules inherent in the camera's
software.


What do you mean by "the source image"?

Pehraps you need to study up on what a raw data file
is, and what a JPEG or TIFF image file is?

Do you know, for example, why the word "interpolation"
(see a good dictionary) is used to describe the process
of converting raw sensor data to an image format?

The data in the RAW file can't be restructured to make a
different image without changing the data.


That is not true. In fact there is far more data in a
raw file than is needed to make an image. Likewise it
is possible to emphasize different parts of the data in
different ways to get different images. That is exactly
what white balance is, for example.

It's also true that while I said that at least 9 sensor
locations are used to generate each pixel, there are
several variations on ways to interpolate the data that
use more than 9. Each method is different.

Did you read, and understand, the following few paragraphs?

A JPEG or TIFF file contains an image. The RAW file
contains data to make an image.

For example, each "sensal" location on the sensor does
*not* translate to a single pixel in the resulting
image. Instead the data from at least 9 different
sensors locations is used to determine the Red, Green,
and Blue values for a single pixel.

The process where all of that data is interpolated is
called "raw conversion", and is much the same as
converting a pile of nails and boards into a house.


If you understood that, then the above part that you
objected to should have made sense. If not, tell me
what you think it all is and I'll try to explain the
significance in a way that is directed at your response
(rather than at the OP for this thread).

--
Floyd L. Davidson http://www.apaflo.com/floyd_davidson
Ukpeagvik (Barrow, Alaska)
  #7  
Old May 31st 09, 10:30 AM posted to rec.photo.digital,uk.rec.photo.misc
Eric Stevens
external usenet poster
 
Posts: 13,611
Default Could you actually see photos made from RAW files?

On Sat, 30 May 2009 21:32:27 -0800, (Floyd L.
Davidson) wrote:

Floyd has failed to point out that at this point he has omitted a
great deal of previous text. I know he has been around more than long
enough to know that this is not the right thing to do.

Eric Stevens wrote:
Floyd, I suspect you have been smoking something which is not good for
you. Subject to statistical error limitations, there is a one to one
correspondence between the source image and the RAW file. One can be
converted to the other using the rules inherent in the camera's
software.


What do you mean by "the source image"?


That which is projected onto the sensor by the lens.

Pehraps you need to study up on what a raw data file
is, and what a JPEG or TIFF image file is?


Perhaps I don't. Perhaps you need to explain what you are trying to
say, preferably without the aid of whatever it is you have snipped
from this article before replying.

Do you know, for example, why the word "interpolation"
(see a good dictionary) is used to describe the process
of converting raw sensor data to an image format?


I know very well what is meant by the word 'interpolation' and the
manner in which this is carried out has nothing whatsoever to do with
the relationship between the source image and the RAW file except to
the extent that it is determined by the rules inherent in the camera's
software.

The data in the RAW file can't be restructured to make a
different image without changing the data.


That is not true. In fact there is far more data in a
raw file than is needed to make an image. Likewise it
is possible to emphasize different parts of the data in
different ways to get different images. That is exactly
what white balance is, for example.


And a change in the white balance involves a change in the interpreted
RAW data: i.e. the white balance can only be changed by changing the
raw data.

It's also true that while I said that at least 9 sensor
locations are used to generate each pixel, there are
several variations on ways to interpolate the data that
use more than 9. Each method is different.


The sensor locations are irrelevant. The RAW data is derived from the
sensors by rules which are determined by the manufacturer of the
camera. The signals generated by the sensors are determined by the
rules inherent in the camera's software. As I have already said, there
is a one to one correspondence between the source image and the RAW
file. You don't have a choice of RAW files for a given image. Nor do
you have a choice of images for a given RAW file.

Did you read, and understand, the following few paragraphs?

A JPEG or TIFF file contains an image. The RAW file
contains data to make an image.

For example, each "sensal" location on the sensor does
*not* translate to a single pixel in the resulting
image. Instead the data from at least 9 different
sensors locations is used to determine the Red, Green,
and Blue values for a single pixel.

The process where all of that data is interpolated is
called "raw conversion", and is much the same as
converting a pile of nails and boards into a house.


If you understood that, then the above part that you
objected to should have made sense. If not, tell me
what you think it all is and I'll try to explain the
significance in a way that is directed at your response
(rather than at the OP for this thread).


JPEGs, TIFFs and RAW files all contain data required to create an
image. The principal difference is that the format of JPEGs and TIFFs
are independent of of the camera which created them while RAW files
are not.



Eric Stevens
  #8  
Old May 31st 09, 12:10 PM posted to rec.photo.digital,uk.rec.photo.misc
Floyd L. Davidson
external usenet poster
 
Posts: 5,138
Default Could you actually see photos made from RAW files?

Eric Stevens wrote:
On Sat, 30 May 2009 21:32:27 -0800, (Floyd L.
Davidson) wrote:
Eric Stevens wrote:


Floyd has failed to point out that at this point he has omitted a
great deal of previous text. I know he has been around more than long
enough to know that this is not the right thing to do.


I've been posting on Usenet for over 20 years Eric, and
I do know that snipping out the part not being commented
on is the right way to edit an article before posting.

When are *you* going to learn that?

you. Subject to statistical error limitations, there is a one to one
correspondence between the source image and the RAW file. One can be
converted to the other using the rules inherent in the camera's
software.


What do you mean by "the source image"?


That which is projected onto the sensor by the lens.


Then your statements above are patently silly on their face.

The raw data is a sampled set drawn from the projected image.
The projected image cannot ever be recreated in its entirety,
nor can the samples even be recreated with precision.

Perhaps you need to explain what you are trying to
say, preferably without the aid of whatever it is you have snipped
from this article before replying.


I certainly have not used text that isn't here, and
don't see how that would be possible!

Do you know, for example, why the word "interpolation"
(see a good dictionary) is used to describe the process
of converting raw sensor data to an image format?


I know very well what is meant by the word 'interpolation' and the
manner in which this is carried out has nothing whatsoever to do with
the relationship between the source image and the RAW file except to
the extent that it is determined by the rules inherent in the camera's
software.


You said the "source image" is what is projected on the
sensor. Interpolation of course is the method by which
the sensor data is converted to an image format for
viewing.

Two very distinctly separate relationships.

The data in the RAW file can't be restructured to make a
different image without changing the data.


That is not true. In fact there is far more data in a
raw file than is needed to make an image. Likewise it
is possible to emphasize different parts of the data in
different ways to get different images. That is exactly
what white balance is, for example.


And a change in the white balance involves a change in the interpreted
RAW data: i.e. the white balance can only be changed by changing the
raw data.


It is quite possible to change the raw data to effect
while balance, but it isn't normally done that way (Nikon,
for example, has hinted that they might be doing exactly
that in hardware).

What is changed is the interpolation of the data when
creating an image format. The raw data is not changed,
and the raw file stays exactly the same. The way the
data is manipulated during interpolation changes.

Regardless of that, it is rather easy to demonstrate
that the raw data is not changed in order to adjust
white balance. Merely convert a RAW file to a JPEG
image and then, using only the JPEG image (which
contains vastly less data that the RAW file), use an
editor to change the white balance and write a new JPEG
file with a different white balance. The raw data is
not even used, much less changed.

It's also true that while I said that at least 9 sensor
locations are used to generate each pixel, there are
several variations on ways to interpolate the data that
use more than 9. Each method is different.


The sensor locations are irrelevant. The RAW data is derived from the
sensors by rules which are determined by the manufacturer of the
camera.


False. Every different raw converter design uses a
different set of "rules". Coffin's dcraw.c uses one
set, Nikon uses another, and several other raw
converters are different from both of those.

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).

The signals generated by the sensors are determined by the
rules inherent in the camera's software.


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.

As I have already said, there
is a one to one correspondence between the source image and the RAW
file.


You can say that all you like, but it still requires at
least *nine* different sensor locations to generate data
for each pixel of the resulting image. It is not a one
to one relationship.

You don't have a choice of RAW files for a given image. Nor do
you have a choice of images for a given RAW file.


But you have a choice of an infinite number of resulting
images when the camera raw data is interpolated. None
of them are exactly the same as your "source image" that
was projected onto the sensor.

If you understood that, then the above part that you
objected to should have made sense. If not, tell me
what you think it all is and I'll try to explain the
significance in a way that is directed at your response
(rather than at the OP for this thread).


JPEGs, TIFFs and RAW files all contain data required to create an
image.


A JPEG or TIFF contains the data for a single image. A
RAW file contains information for something approaching
an infinite number of images.

The principal difference is that the format of JPEGs and TIFFs
are independent of of the camera which created them while RAW files
are not.


The JPEG and TIFF images are no more, or less,
independent of the camera than the RAW data.

--
Floyd L. Davidson http://www.apaflo.com/floyd_davidson
Ukpeagvik (Barrow, Alaska)

  #9  
Old May 31st 09, 11:27 PM posted to rec.photo.digital,uk.rec.photo.misc
Eric Stevens
external usenet poster
 
Posts: 13,611
Default Could you actually see photos made from RAW files?

On Sun, 31 May 2009 03:10:56 -0800, (Floyd L.
Davidson) wrote:

Eric Stevens wrote:
On Sat, 30 May 2009 21:32:27 -0800,
(Floyd L.
Davidson) wrote:
Eric Stevens wrote:


Floyd has failed to point out that at this point he has omitted a
great deal of previous text. I know he has been around more than long
enough to know that this is not the right thing to do.


I've been posting on Usenet for over 20 years Eric, and
I do know that snipping out the part not being commented
on is the right way to edit an article before posting.


I wasn't complaining about you deleting the text. It was your failure
to point out that you have deleted text, which I criticised.

When are *you* going to learn that?


When are you going to mark your deletions.

you. Subject to statistical error limitations, there is a one to one
correspondence between the source image and the RAW file. One can be
converted to the other using the rules inherent in the camera's
software.

What do you mean by "the source image"?


That which is projected onto the sensor by the lens.


Then your statements above are patently silly on their face.

The raw data is a sampled set drawn from the projected image.
The projected image cannot ever be recreated in its entirety,
nor can the samples even be recreated with precision.


What do you think I meant by 'statisticsl error limitations'?

Perhaps you need to explain what you are trying to
say, preferably without the aid of whatever it is you have snipped
from this article before replying.


I certainly have not used text that isn't here, and
don't see how that would be possible!


Yet you claim it is possible to create an image from data that isn't
there!

Do you know, for example, why the word "interpolation"
(see a good dictionary) is used to describe the process
of converting raw sensor data to an image format?


I know very well what is meant by the word 'interpolation' and the
manner in which this is carried out has nothing whatsoever to do with
the relationship between the source image and the RAW file except to
the extent that it is determined by the rules inherent in the camera's
software.


You said the "source image" is what is projected on the
sensor. Interpolation of course is the method by which
the sensor data is converted to an image format for
viewing.


That's part of what I meant when I wrote of "the rules inherent in the
camera's software".

Two very distinctly separate relationships.

The data in the RAW file can't be restructured to make a
different image without changing the data.

That is not true. In fact there is far more data in a
raw file than is needed to make an image. Likewise it
is possible to emphasize different parts of the data in
different ways to get different images. That is exactly
what white balance is, for example.


And a change in the white balance involves a change in the interpreted
RAW data: i.e. the white balance can only be changed by changing the
raw data.


It is quite possible to change the raw data to effect
while balance, but it isn't normally done that way (Nikon,
for example, has hinted that they might be doing exactly
that in hardware).


.... and therefore it is a different image. But nevertheless there is
only the one image which can be created from a set of unmodified raw
data.

What is changed is the interpolation of the data when
creating an image format. The raw data is not changed,
and the raw file stays exactly the same. The way the
data is manipulated during interpolation changes.


An interpolated data set is a new data set.

Regardless of that, it is rather easy to demonstrate
that the raw data is not changed in order to adjust
white balance. Merely convert a RAW file to a JPEG
image and then, using only the JPEG image (which
contains vastly less data that the RAW file), use an
editor to change the white balance and write a new JPEG
file with a different white balance. The raw data is
not even used, much less changed.


But only the one JPEG can be created from the RAW data providing the
rules of the transformation do not change.

It's also true that while I said that at least 9 sensor
locations are used to generate each pixel, there are
several variations on ways to interpolate the data that
use more than 9. Each method is different.


The sensor locations are irrelevant. The RAW data is derived from the
sensors by rules which are determined by the manufacturer of the
camera.


False. Every different raw converter design uses a
different set of "rules". Coffin's dcraw.c uses one
set, Nikon uses another, and several other raw
converters are different from both of those.


But they are working on the camera's saved RAW file, not the
relationship between what the sensor sees and the saved RAW file.

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?

The signals generated by the sensors are determined by the
rules inherent in the camera's software.


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'.

As I have already said, there
is a one to one correspondence between the source image and the RAW
file.


You can say that all you like, but it still requires at
least *nine* different sensor locations to generate data
for each pixel of the resulting image. It is not a one
to one relationship.


I see the problem. You misunderstand what I mean by 'one to one'. By
that expression I mean that one imgage transforms into one RAW data
set. Its not as though the transformation entails (say) a quadratic
equation where the one image can give rise to either one of two RAW
data sets. See
http://www.yourdictionary.com/one-to-one

You don't have a choice of RAW files for a given image. Nor do
you have a choice of images for a given RAW file.


But you have a choice of an infinite number of resulting
images when the camera raw data is interpolated. None
of them are exactly the same as your "source image" that
was projected onto the sensor.


.... and none of them are the image defined by the RAW data. Close,
maybe, but not exact.

If you understood that, then the above part that you
objected to should have made sense. If not, tell me
what you think it all is and I'll try to explain the
significance in a way that is directed at your response
(rather than at the OP for this thread).


JPEGs, TIFFs and RAW files all contain data required to create an
image.


A JPEG or TIFF contains the data for a single image. A
RAW file contains information for something approaching
an infinite number of images.

The principal difference is that the format of JPEGs and TIFFs
are independent of of the camera which created them while RAW files
are not.


The JPEG and TIFF images are no more, or less,
independent of the camera than the RAW data.




Eric Stevens
  #10  
Old June 1st 09, 01:11 AM posted to rec.photo.digital,uk.rec.photo.misc
Floyd L. Davidson
external usenet poster
 
Posts: 5,138
Default Could you actually see photos made from RAW files?

Eric Stevens wrote:
On Sun, 31 May 2009 03:10:56 -0800, (Floyd L.
Davidson) wrote:
When are you going to mark your deletions.


You still haven't figured out how it works, have you.

What do you think I meant by 'statisticsl error limitations'?


You meant to imply that using big words with no meaning
will make it sound like you understand something you
don't. But anyone who does understand the process can
see that you don't.

Yet you claim it is possible to create an image from data that isn't
there!


I have never said any such thing, and see no point in you
making up distortions rather than discussion the topic at
hand.

You said the "source image" is what is projected on the
sensor. Interpolation of course is the method by which
the sensor data is converted to an image format for
viewing.


That's part of what I meant when I wrote of "the rules inherent in the
camera's software".


And you haven't yet figure out that one is the input to while
the other is an output from.

It is quite possible to change the raw data to effect
while balance, but it isn't normally done that way (Nikon,
for example, has hinted that they might be doing exactly
that in hardware).


... and therefore it is a different image. But nevertheless there is
only the one image which can be created from a set of unmodified raw
data.


But clearly that is not true. The raw data set does not
define one single image. It can be interpolated to
produce an image. But the interpolation can be done in
a nearly infinite number of ways, each of which produces
a *different* image. No one way is the _right_ way,
they are all just as correct as the next.

What is changed is the interpolation of the data when
creating an image format. The raw data is not changed,
and the raw file stays exactly the same. The way the
data is manipulated during interpolation changes.


An interpolated data set is a new data set.


The interpolation does not produce a new raw data set.
It produces an unique image.

But only the one JPEG can be created from the RAW data providing the
rules of the transformation do not change.


There is no one set of correct "rules of the
transformation".

False. Every different raw converter design uses a
different set of "rules". Coffin's dcraw.c uses one
set, Nikon uses another, and several other raw
converters are different from both of those.


But they are working on the camera's saved RAW file, not the
relationship between what the sensor sees and the saved RAW file.


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.

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.

The signals generated by the sensors are determined by the
rules inherent in the camera's software.


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'.


I quoted you exactly above. Now you want to change 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.

As I have already said, there
is a one to one correspondence between the source image and the RAW
file.


You can say that all you like, but it still requires at
least *nine* different sensor locations to generate data
for each pixel of the resulting image. It is not a one
to one relationship.


I see the problem. You misunderstand what I mean by 'one to one'. By
that expression I mean that one imgage transforms into one RAW data
set. Its not as though the transformation entails (say) a quadratic
equation where the one image can give rise to either one of two RAW
data sets. See
http://www.yourdictionary.com/one-to-one

So you now admit that it is not software at all, but a
hard wired hardware transform.

By next weekend we may force you into writing something
that is clear enough to make some sense.

You don't have a choice of RAW files for a given image. Nor do
you have a choice of images for a given RAW file.


But you have a choice of an infinite number of resulting
images when the camera raw data is interpolated. None
of them are exactly the same as your "source image" that
was projected onto the sensor.


... and none of them are the image defined by the RAW data. Close,
maybe, but not exact.


That is precisely what I've been trying to get through
your head! Good. Now you can get on with a sane
discusssion of raw data processing.

The raw data does not define one specific image. When
the data is interpolated there is then an image!

--
Floyd L. Davidson http://www.apaflo.com/floyd_davidson
Ukpeagvik (Barrow, Alaska)
 




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