PhotoBanter.com - View Single Post - Could you actually see photos made from RAW files?

**Eric Stevens** · May 31st 09, 05:37 AM posted to rec.photo.digital,uk.rec.photo.misc

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