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Tell me again, what's the big deal about RAW images?

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Anonymous
July 8, 2005 11:46:56 PM

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

Okay, I've finally installed Photoshop CS2 and now have a program that can
manipulate the RAW image format from my Nikon D70.

In a completely uncontrolled test (I'll do a formal shoot-off later) I took
a few pictures of flowers in the garden using the RAW format for recording
and imported them into Photoshop. At least with the Mark One Eyeball
Sensor, I didn't see anything different than I would have expected to see if
I had used the JPEG-Fine mode I've been using, other than files that are
twice as big (6MB vs 3MB).

Is there something I'm supposed to be able to do with the RAW format images
that I can't do with the JPEGs?

Is the resolution better?

What?

TIA
Norm

More about : big deal raw images

Anonymous
July 8, 2005 11:46:57 PM

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

> Is there something I'm supposed to be able to do with the RAW format
> images
> that I can't do with the JPEGs?

Easier to fix white balance and you avoid in-camera algorithms that might
not always be as good as what you can do in post-processing.

> Is the resolution better?

Dynamic range is better.

Check this:
http://www.digitalphotobook.net/tutorials/camera_raw/ca...

RAW takes time and it might not be worth it in your case. It offers no huge
advantages for most shots.
July 8, 2005 11:46:57 PM

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

If you like to spend lots of time to get your image perfect in your
eyes, RAW is for you. If you just want excellent images, high quality
JPEGS are fine.
If you showed an expert 2 different images, he would be guessing to say
which was RAW,
Don
Related resources
Anonymous
July 8, 2005 11:46:57 PM

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

"Norm Dresner" <ndrez@att.net> wrote in
news:QKAze.401133$cg1.308705@bgtnsc04-news.ops.worldnet.att.net:

> Is there something I'm supposed to be able to do with the RAW format
> images that I can't do with the JPEGs?

If your picture is exactly as you want it, then jpeg is fine. But the
jpeg is 'frozen'. The 12-bit values are white balanced, exposure
adjusted, sharpened, saturated, etc. and then whacked down to 8-bits. Any
changes you attempt to make to it will lower the quality of the result.

The NEF lets you make much more dramatic changes to the picture without
losing quality. If you accidentally screw up a great shot and have no
easy way to go back and take the shot again the NEF gives you much more
leeway in saving it. It's not a panacea, and the resulting picture won't
look as good as if you'd taken the picture properly, but it'll certainly
look better than what you could get out of the jpeg. The D-Lighting/boost
shadow stuff is especially effective.

Since storage is cheap now and the D70 doesn't really take any longer to
process NEFs than JPGs I shoot everything in NEF and occasionally it
saves me. YMMV!
Anonymous
July 8, 2005 11:46:58 PM

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

In article <1120855895.108594.209160@z14g2000cwz.googlegroups.com>,
DonB <oink@woosh.co.nz> wrote:

> If you like to spend lots of time to get your image perfect in your
> eyes, RAW is for you. If you just want excellent images, high quality
> JPEGS are fine.
> If you showed an expert 2 different images, he would be guessing to say
> which was RAW,

I usually don't spend much more than 30 seconds (if that long)
importing a RAW image into PhotoShop. Considering the control I have,
the results are worth it.
Anonymous
July 9, 2005 12:52:01 AM

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

"Charles Schuler" <charleschuler@comcast.net> wrote in message
news:UPmdnfqazPkaQ1PfRVn-3w@comcast.com...
>
>
>> Is there something I'm supposed to be able to do with the RAW format
>> images
>> that I can't do with the JPEGs?
>
> Easier to fix white balance and you avoid in-camera algorithms that might
> not always be as good as what you can do in post-processing.
>
>> Is the resolution better?
>
> Dynamic range is better.
>
> Check this:
> http://www.digitalphotobook.net/tutorials/camera_raw/ca...
>
> RAW takes time and it might not be worth it in your case. It offers no
> huge advantages for most shots.

Under "difficult" conditions you should probably use it though.
Anonymous
July 9, 2005 1:02:35 AM

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

On Fri, 08 Jul 2005 19:46:56 GMT, "Norm Dresner" <ndrez@att.net>
wrote:

>Okay, I've finally installed Photoshop CS2 and now have a program that can
>manipulate the RAW image format from my Nikon D70.
>
>In a completely uncontrolled test (I'll do a formal shoot-off later) I took
>a few pictures of flowers in the garden using the RAW format for recording
>and imported them into Photoshop. At least with the Mark One Eyeball
>Sensor, I didn't see anything different than I would have expected to see if
>I had used the JPEG-Fine mode I've been using, other than files that are
>twice as big (6MB vs 3MB).

In other words, they both look as average as each other.

>Is there something I'm supposed to be able to do with the RAW format images
>that I can't do with the JPEGs?

Yes, correct / improve a number of aspects about them during the
import process.

>Is the resolution better?

No.

>What?

So, you are telling me that:

The exposure was spot on, and you didn't need to increase/decrease the
exposure or shadows slider to give a more pleasing/stunning image.

The color balance was perfect, and it didn't look any better slightly
cooler or warmer than the camera's choice.

The lens amazingly showed no vignetting that you wanted to eliminate
or even enhance for artistic reasons.

The saturation was spot on.

The sharpness, luminance smoothing and color noise reduction was
exactly correct.

.....because, I don't believe you ;-)

Go back, twiddle the sliders and if you still think the JPEG looks as
good or better, switch to shooting JPEG.

Also, be certain that you are *not* using the Nikon RAW importer
inside Photoshop, it's junk.

--
Owamanga!
http://www.pbase.com/owamanga
Anonymous
July 9, 2005 1:02:36 AM

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

Owamanga <owamanga-not-this-bit@hotmail.com> wrote:

> On Fri, 08 Jul 2005 19:46:56 GMT, "Norm Dresner" <ndrez@att.net> wrote:
[..]
> >Is the resolution better?
>
> No.

The resolution of the RAW file itself isn't any better or worse in terms
of pixel count, but you can interpolate a larger image very easily
during the import process. This enlargement will look much, much, (that
is: *MUCH*) better than an enlargment of a JPEG.

Lossy compression is the enemy. I wish camera manufacturers would start
allowing their cameras to output PNG. In fact, I wish I could run linux
on my DSLR. O-Well. :-)
Anonymous
July 9, 2005 3:36:22 AM

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

"Charles Schuler" <charleschuler@comcast.net> wrote in message
news:UPmdnfqazPkaQ1PfRVn-3w@comcast.com...
>
>
> > Is there something I'm supposed to be able to do with the RAW format
> > images
> > that I can't do with the JPEGs?
>

You're saying that I can manipulate the color balance better in the raw
format than I can by using levels and curves on the JPEG in Photoshop,
right?

> Easier to fix white balance and you avoid in-camera algorithms that might
> not always be as good as what you can do in post-processing.
>
> > Is the resolution better?
>
> Dynamic range is better.

Since the number of bits per pixel is the same in both, there's got to be
something else going on then, right?

I'm guessing but I think what you're implying is that the camera, to produce
the JPEG, assigns binary values to the various brightness levels in a
non-linear and non-uniform way, right?

If that's the case, then the RAW format more closely resembles the range of
brightness in the original image but since the number of bits per pixel is
the same (at least think it is), then the brightness seen on the screen has
to have the same range, doesn't it?

Thanks
Norm
Anonymous
July 9, 2005 3:36:23 AM

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

On Fri, 08 Jul 2005 23:36:22 GMT, "Norm Dresner" <ndrez@att.net>
wrote:

>I'm guessing but I think what you're implying is that the camera, to produce
>the JPEG, assigns binary values to the various brightness levels in a
>non-linear and non-uniform way, right?
>
>If that's the case, then the RAW format more closely resembles the range of
>brightness in the original image but since the number of bits per pixel is
>the same (at least think it is), then the brightness seen on the screen has
>to have the same range, doesn't it?


If you're comfortable with the processor in your camera making all the
decisions on saturation, exposure, white balance, sharpening,
luminance smoothing, and noise reduction then you should probably
shoot jpegs and not worry about it. If you really want to learn more
about the advantages of shooting raw you should probably download free
from Adobe:

http://www.adobe.com/digitalimag/pdfs/understanding_dig...

http://www.adobe.com/digitalimag/pdfs/ps_workflow_sec1....

There are 4 parts to the workflow article, just change the section
numbers to get all of them.
Anonymous
July 9, 2005 3:39:38 AM

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

"Norm Dresner" <ndrez@att.net> wrote in message
news:W5Eze.1105337$w62.93039@bgtnsc05-news.ops.worldnet.att.net...
> "Charles Schuler" <charleschuler@comcast.net> wrote in message
> news:UPmdnfqazPkaQ1PfRVn-3w@comcast.com...
>>
>>
>> > Is there something I'm supposed to be able to do with the RAW format
>> > images
>> > that I can't do with the JPEGs?
>>
>
> You're saying that I can manipulate the color balance better in the raw
> format than I can by using levels and curves on the JPEG in Photoshop,
> right?
>
>> Easier to fix white balance and you avoid in-camera algorithms that might
>> not always be as good as what you can do in post-processing.
>>
>> > Is the resolution better?
>>
>> Dynamic range is better.
>
> Since the number of bits per pixel is the same in both, there's got to be
> something else going on then, right?
>
> I'm guessing but I think what you're implying is that the camera, to
> produce
> the JPEG, assigns binary values to the various brightness levels in a
> non-linear and non-uniform way, right?
>
> If that's the case, then the RAW format more closely resembles the range
> of
> brightness in the original image but since the number of bits per pixel is
> the same (at least think it is), then the brightness seen on the screen
> has
> to have the same range, doesn't it?
>
> Thanks
> Norm
>

Actually the number of bits per pixel is NOT the same. RAW = 16 bits, JPEG
= 8 bits. JPEG compresses the dynamic range dramatically.
Anonymous
July 9, 2005 3:39:39 AM

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

Tom Scales <tomtoo@softhome.net> wrote:

> "Norm Dresner" <ndrez@att.net> wrote in message
> news:W5Eze.1105337$w62.93039@bgtnsc05-news.ops.worldnet.att.net...
> > "Charles Schuler" <charleschuler@comcast.net> wrote in message
> > news:UPmdnfqazPkaQ1PfRVn-3w@comcast.com...
[..]
> >> Dynamic range is better.
> >
> > Since the number of bits per pixel is the same in both, there's got to
> > be something else going on then, right?
> >
> > I'm guessing but I think what you're implying is that the camera, to
> > produce the JPEG, assigns binary values to the various brightness levels
> > in a non-linear and non-uniform way, right?
> >
> > If that's the case, then the RAW format more closely resembles the range
> > of brightness in the original image but since the number of bits per
> > pixel is the same (at least think it is), then the brightness seen on
> > the screen has to have the same range, doesn't it?
>
> Actually the number of bits per pixel is NOT the same. RAW = 16 bits,
> JPEG = 8 bits. JPEG compresses the dynamic range dramatically.

That's not exactly true. Most RAW file formats are 12 bits per channel
(bpc), and typically what you'd do is import that into Photoshop as 16
bpc, and then save as a TIFF or JPEG or whatever, at however many bpc
you need.

The advantage is that the difference between 12 bpc and 8 bpc isn't
automatically lost in JPEG compression, and if you end up making a JPEG,
you can correct for loss of dynamic range and control the compression
yourself.

Some folks might not cherish the idea of going through this process in
order to tweak the hell out of the image this way, and for those people
the JPEG fine setting is just that: fine.
Anonymous
July 9, 2005 6:56:59 AM

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

Less than 2 minutes got me very good results in curves only. Yes, I
worked on the jpeg and compression hasn't helped much, as the histogram
shows. Without see the cup itself it's hard to know what looks best,
but I'm not so sure RAW is a big deal for colour casts.

http://www.theimageplane.net/postimages/cup.jpg
Anonymous
July 9, 2005 12:31:05 PM

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

Paul Mitchum wrote:
[]
> Lossy compression is the enemy. I wish camera manufacturers would
> start allowing their cameras to output PNG. In fact, I wish I could
> run linux on my DSLR. O-Well. :-)

Perhaps you could run Linux if your camera was built into a PDA. I'm sure
it would be much better than any DSLR! <G>

David
Anonymous
July 9, 2005 12:58:23 PM

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

Tom Scales wrote:
[]
> Actually the number of bits per pixel is NOT the same. RAW = 16
> bits, JPEG = 8 bits. JPEG compresses the dynamic range dramatically.

Not quite true - the JPEG is gamma corrected, meaning that the dynamic
range is similar to that of the sensor, but the luminance steps in the
JPEG are non-linear.

David
Anonymous
July 9, 2005 6:03:00 PM

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

Norm Dresner <ndrez@att.net> wrote:
> Okay, I've finally installed Photoshop CS2 and now have a program that can
> manipulate the RAW image format from my Nikon D70.

> In a completely uncontrolled test (I'll do a formal shoot-off later)
> I took a few pictures of flowers in the garden using the RAW format
> for recording and imported them into Photoshop. At least with the
> Mark One Eyeball Sensor, I didn't see anything different than I
> would have expected to see if I had used the JPEG-Fine mode I've
> been using, other than files that are twice as big (6MB vs 3MB).

> Is there something I'm supposed to be able to do with the RAW format
> images that I can't do with the JPEGs?

The colour gamut of your camera (and your Mark One Eyeball) is far
greater than that of your PC's monitor or your printer. So, when
displaying a digital image it's necessary to map a large colour space
onto a smaller colour space. This process is known as colour
rendering". (The colour spaces used in camera are usually sRGB or
Adobe RGB. Adobe RGB is a larger space so it can record more colours,
but it's still a lot smaller than that of the camera.)

If you use JPEG, the colour rendering is done by your camera at the
point of taking the photograph, without any control from you. The
result of this can be a photograph of oranges and tomatoes that appear
to be the same colour, because both are outside the colour gamut used
in the JPEG. If you had used RAW, the oranges and tomatoes would have
been recorded as being different colours, and you could have adjusted
the image later to make them look distinct. If you use JPEG there's
nothing you can do: the different colours have been lost.

It might well be that you got lucky with the flowers in your garden --
perhaps all of them were within the colour gamut of the colour space
used in your JPEGs. But that's pretty unlikely really, as flowers are
wildly colourful, especially in direct sunlight.

Andrew.
Anonymous
July 9, 2005 7:09:33 PM

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

"McLeod" <cerveza@xplornet.com> wrote in message
news:to4uc1hbfj89p7che3e76khugrhmq2lgf9@4ax.com...
> On Fri, 08 Jul 2005 23:36:22 GMT, "Norm Dresner" <ndrez@att.net>
> wrote:
>
> >I'm guessing but I think what you're implying is that the camera, to
produce
> >the JPEG, assigns binary values to the various brightness levels in a
> >non-linear and non-uniform way, right?
> >
> >If that's the case, then the RAW format more closely resembles the range
of
> >brightness in the original image but since the number of bits per pixel
is
> >the same (at least think it is), then the brightness seen on the screen
has
> >to have the same range, doesn't it?
>
>
> If you're comfortable with the processor in your camera making all the
> decisions on saturation, exposure, white balance, sharpening,
> luminance smoothing, and noise reduction then you should probably
> shoot jpegs and not worry about it. If you really want to learn more
> about the advantages of shooting raw you should probably download free
> from Adobe:
>
> http://www.adobe.com/digitalimag/pdfs/understanding_dig...
>
> http://www.adobe.com/digitalimag/pdfs/ps_workflow_sec1....
>
> There are 4 parts to the workflow article, just change the section
> numbers to get all of them.

These look like some very interesting documents and I'll study them before I
ask any more questions.

Thanks
Norm
Anonymous
July 9, 2005 9:50:56 PM

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

In message <QKAze.401133$cg1.308705@bgtnsc04-news.ops.worldnet.att.net>,
"Norm Dresner" <ndrez@att.net> wrote:

>Is there something I'm supposed to be able to do with the RAW format images
>that I can't do with the JPEGs?

Only if you have to change white balance, apply curves, get more
highlights or shadows, etc.

>Is the resolution better?

Technically, no, but you can get more detail sometimes if you process
correctly.

>What?

RAW makes it possible to make adjustments in one step (doing them twice
or more increases posterization), and get more dynamic range out of the
shot.
--

<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
John P Sheehy <JPS@no.komm>
><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
Anonymous
July 9, 2005 9:56:28 PM

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

In message <_8Eze.146200$VH2.144443@tornado.tampabay.rr.com>,
"Tom Scales" <tomtoo@softhome.net> wrote:

>Actually the number of bits per pixel is NOT the same. RAW = 16 bits, JPEG
>= 8 bits. JPEG compresses the dynamic range dramatically.

I *wish* RAW were 16 bits. It is generally 12 bits.
--

<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
John P Sheehy <JPS@no.komm>
><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
Anonymous
July 9, 2005 9:59:01 PM

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

In message <PkMze.66070$G8.63663@text.news.blueyonder.co.uk>,
"David J Taylor"
<david-taylor@blueyonder.co.not-this-bit.nor-this-part.uk.invalid>
wrote:

>Tom Scales wrote:
>[]
>> Actually the number of bits per pixel is NOT the same. RAW = 16
>> bits, JPEG = 8 bits. JPEG compresses the dynamic range dramatically.
>
>Not quite true - the JPEG is gamma corrected, meaning that the dynamic
>range is similar to that of the sensor, but the luminance steps in the
>JPEG are non-linear.

In-camera JPEGs typically either clip away a good deal of highlight
range from the RAW, or may compress part of the range so that they are
good as-is in the output, but are not particularly editable in that
range due to posterization.
--

<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
John P Sheehy <JPS@no.komm>
><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
Anonymous
July 9, 2005 10:01:26 PM

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

In message <1120855895.108594.209160@z14g2000cwz.googlegroups.com>,
"DonB" <oink@woosh.co.nz> wrote:

>If you showed an expert 2 different images, he would be guessing to say
>which was RAW,

Not if there were very bright highlights clipped away by the RAW.
--

<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
John P Sheehy <JPS@no.komm>
><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
Anonymous
July 10, 2005 12:45:57 AM

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

<JPS@no.komm> wrote in message
news:4s30d15h4lmq5ir124ppnafg0rjocv4m2h@4ax.com...
> In message <_8Eze.146200$VH2.144443@tornado.tampabay.rr.com>,
> "Tom Scales" <tomtoo@softhome.net> wrote:
>
> >Actually the number of bits per pixel is NOT the same. RAW = 16 bits,
JPEG
> >= 8 bits. JPEG compresses the dynamic range dramatically.
>
> I *wish* RAW were 16 bits. It is generally 12 bits.
> --

But 12 bits gives you 16 times the range that 8 bits does. That's a range
of 4096:1 which covers a range of 12 f-stops (or 12 EV brightness) which is,
if not huge, then certainly enough for almost all but the most demanding
work. How many color (print) films can match that? I can tell you that at
least for prints in the 4x6" through 8x10" range that even the 8-bits you
get with a JPEG format is enough to garner "WOW" from most people if applied
properly. Museum quality? No way! But then I'd doubt that even the 20-odd
megapixel backs for Hasselblads can do that yet. Right now, if I think I'm
going to want to produce a "keeper" print of some subject, I'll switch from
the D70 to the N90 which is usually loaded with Kodachrome these days.

Norm
July 10, 2005 12:45:58 AM

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

Norm Dresner wrote:

>
> But 12 bits gives you 16 times the range that 8 bits does. That's a range
> of 4096:1 which covers a range of 12 f-stops (or 12 EV brightness) which
> is, if not huge, then certainly enough for almost all but the most
> demanding
> work. How many color (print) films can match that?

???? The dynamic range lost isn't due to 8bit vs 16 bit. It's because the in
camera jpeg's dynamic range has been compressed to fit within the contrast
setting you have selected. * bits will nromally work fine is used in a
smaller color space like sRGB, when you go to the larger color spaces, the
gaps between the different colors becomes larger and you might begin to see
posterization when you start editing the color balance etc.
--

Stacey
Anonymous
July 10, 2005 12:58:33 AM

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

Norm Dresner <ndrez@att.net> wrote:

>> I *wish* RAW were 16 bits. It is generally 12 bits.
>
> But 12 bits gives you 16 times the range that 8 bits does. That's a range
> of 4096:1 which covers a range of 12 f-stops (or 12 EV brightness) which is,
> if not huge, then certainly enough for almost all but the most demanding
> work. How many color (print) films can match that?

That's not the point -- the point is that each successively darker stop of
range uses half the number of levels, so those lowest (darkest) stops in the
range lose most of their detail to posterization. So you really want several
more stops of range than you actually intend to use, so that you can clip off
the dark end of the range without losing anything you actually wanted to keep.

--
Jeremy | jeremy@exit109.com
July 10, 2005 12:58:34 AM

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

Jeremy Nixon wrote:

> Norm Dresner <ndrez@att.net> wrote:
>
>>> I *wish* RAW were 16 bits. It is generally 12 bits.
>>
>> But 12 bits gives you 16 times the range that 8 bits does. That's a
>> range of 4096:1 which covers a range of 12 f-stops (or 12 EV brightness)
>> which is, if not huge, then certainly enough for almost all but the most
>> demanding
>> work. How many color (print) films can match that?
>
> That's not the point -- the point is that each successively darker stop of
> range uses half the number of levels, so those lowest (darkest) stops in
> the
> range lose most of their detail to posterization. So you really want
> several more stops of range than you actually intend to use, so that you
> can clip off the dark end of the range without losing anything you
> actually wanted to keep.
>

I thought it was more that you gain precision in the colors, not more
dynamic range in f-stops. The reason the in camera jpegs have lower dynamic
range is because the contrast level is fixed and they have to fit the shot
into the set contrast range. I've not noticed any dynamic range clipping in
images -developed- from RAW files as 8 bit rather than 16 bit, but have
seen some posterization when editing the color of 8 bit images, especially
if using some of the larger color spaces like aRGB or proRGB.
--

Stacey
Anonymous
July 10, 2005 3:16:49 AM

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

Stacey <fotocord@yahoo.com> wrote:

> I thought it was more that you gain precision in the colors, not more
> dynamic range in f-stops.

The two go hand-in-hand. Because each successively darker stop has half
the tonal values available to it, there comes a point where there is so
little precision that the recorded data is not very useful, despite the
fact that it is there. When an entire stop of brightness has only 4
different values to represent it, you're not going to get much out of
it, even if it is clean and noise-free.

Getting more dynamic range is also a benefit, and is not the same thing
as the range in the gamma-corrected 8-bit final output since you could
process the 16-bit original to use the greater range in different ways.

> I've not noticed any dynamic range clipping in images -developed- from
> RAW files as 8 bit rather than 16 bit, but have seen some posterization
> when editing the color of 8 bit images,

There is no problem with 8-bit for final output. Editing color in 8-bit,
however, can cause significant loss.

But, if you could capture (say) 15 stops of dynamic range in your original
RAW file, you'd be at an advantage. You know from the start that you can't
actually represent them all accurately (without compression) in an 8-bit
final output, but that's not the point -- you may not need *all* of them,
but you may need (for example) two ranges that are 10 stops apart in
brightness, and be willing to compress the midtones because they aren't
as important to your image. Or you may have vast areas of shadow detail
that you need recorded perfectly, but not need much "special" treatment
in your highlights. So, there would be real benefits all around in having
true 16-bit capture of a wide dynamic range.

--
Jeremy | jeremy@exit109.com
Anonymous
July 10, 2005 8:02:51 AM

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

In message
<9IWze.1110650$w62.292513@bgtnsc05-news.ops.worldnet.att.net>,
"Norm Dresner" <ndrez@att.net> wrote:

><JPS@no.komm> wrote in message
>news:4s30d15h4lmq5ir124ppnafg0rjocv4m2h@4ax.com...

>> I *wish* RAW were 16 bits. It is generally 12 bits.

>But 12 bits gives you 16 times the range that 8 bits does.

The number of bits have more to do with precision than range. 12 bits
of linear precision, as used in RAW, is actually less precise in the
deep shadows than 8 bits of gamma-adjusted data, as you have in typical
8-bit graphics files, in the shadows.

>That's a range
>of 4096:1 which covers a range of 12 f-stops (or 12 EV brightness) which is,
>if not huge, then certainly enough for almost all but the most demanding
>work.

It's not that simple; first of all, in a typical exposure, not all 4096
values are even used. On Canon 10D, for instance, the numbers 125 to
about 1200 are all that are used for the 0 to 255 in the red channel of
a JPEG, with normal contrast and daylight white balance.

Secondly, 11 stops of digital numbers does not mean that each stop has
the same level of usability, even if noise is ignored. You need several
different linear levels, at least, to have a reasonable signal in the
shadows. The sensors on most current DSLRs have more dynamic range than
can be rendered in 12 bits, and you can see this in the shadows of ISO
100 images; they are clearly posterized, and if you boost the shadows,
they are ugly as hell, and are inferior to shooting the image with the
same absolute exposure at a higher ISO. If ISO 100 had 16 bits of
high-quality digitization, it would revolutionize the way most people
use exposure and ISO; you could leave the camera set to "sunny f/16" or
f/11 or whatever, in manual mode, and still get a decent image if you
pointed the camera into the shade. Right now, you'd boost it in
software and it would get ugly, because it doesn't have enough bit
depth.

>How many color (print) films can match that? I can tell you that at
>least for prints in the 4x6" through 8x10" range that even the 8-bits you
>get with a JPEG format is enough to garner "WOW" from most people if applied
>properly. Museum quality? No way! But then I'd doubt that even the 20-odd
>megapixel backs for Hasselblads can do that yet. Right now, if I think I'm
>going to want to produce a "keeper" print of some subject, I'll switch from
>the D70 to the N90 which is usually loaded with Kodachrome these days.

It is time to go to sleep, but I hope you see from the rest of my post
that your last paragraph here is not relevant to the issue, IMO.
--

<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
John P Sheehy <JPS@no.komm>
><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
Anonymous
July 10, 2005 8:05:52 AM

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

In message <11d0ejpnbjauk4a@corp.supernews.com>,
Jeremy Nixon <jeremy@exit109.com> wrote:

>Norm Dresner <ndrez@att.net> wrote:
>
>>> I *wish* RAW were 16 bits. It is generally 12 bits.
>>
>> But 12 bits gives you 16 times the range that 8 bits does. That's a range
>> of 4096:1 which covers a range of 12 f-stops (or 12 EV brightness) which is,
>> if not huge, then certainly enough for almost all but the most demanding
>> work. How many color (print) films can match that?
>
>That's not the point -- the point is that each successively darker stop of
>range uses half the number of levels, so those lowest (darkest) stops in the
>range lose most of their detail to posterization. So you really want several
>more stops of range than you actually intend to use, so that you can clip off
>the dark end of the range without losing anything you actually wanted to keep.

Or just keep it dark.

Clipping always happens at the high end, but clipping at the bottom is
kind of optional. It's not like east/west, or top/bottom. You can
always have more illumination; you can not have less than zero, unless
you are running a photon deficit!
--

<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
John P Sheehy <JPS@no.komm>
><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
July 10, 2005 8:05:53 AM

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

JPS@no.komm wrote:

>
> Clipping always happens at the high end, but clipping at the bottom is
> kind of optional.

But that is exactly what they do with the in camera jpegs, they clip the top
and bottom to fit within the contrast range set. IMHO the sensors aren't
good enough right now to worry too much about 12bit being an issue.
--

Stacey
Anonymous
July 10, 2005 8:13:54 AM

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

In message <3jasueFog8s6U1@individual.net>,
Stacey <fotocord@yahoo.com> wrote:

>I thought it was more that you gain precision in the colors, not more
>dynamic range in f-stops.

Even if you don't gain any dynamic range at the highlight end (in a
particular number system), you do at the shadow end, ignoring noise and
amplification and digitization quality, with a higher bit depth. Of
course, in the real world, there are limitations.

Most DSLRs are limited in dynamic range at ISO 100 by the 12-bit
digitization; not the sensor noise.
--

<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
John P Sheehy <JPS@no.komm>
><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
Anonymous
July 10, 2005 12:25:22 PM

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

Stacey <fotocord@yahoo.com> wrote:
> JPS@no.komm wrote:
>
>> Clipping always happens at the high end, but clipping at the bottom is
>> kind of optional.
>
> But that is exactly what they do with the in camera jpegs, they clip the top
> and bottom to fit within the contrast range set.

Right. Now, what if you don't want it to clip at the top, but don't care as
much about the bottom? Or vice-versa? Or what if you really do care about
both, but aren't concerned about the midtones? The "default" algorithm is
a general case and can't take into account the needs of a particular image.

> IMHO the sensors aren't good enough right now to worry too much about
> 12bit being an issue.

On the contrary, their capabilities (at least at low ISO) seem to be
limited by the 12-bit data representation rather than the sensor itself.
I say that not knowing the first thing about A/D converter design,
though, so it's really easy for me to say "use a 16 bit conversion"
when I have no idea what technical barriers prevent that from happening.

--
Jeremy | jeremy@exit109.com
Anonymous
July 10, 2005 3:08:56 PM

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

Stacey <fotocord@yahoo.com> wrote:

>JPS@no.komm wrote:
>
>>
>> Clipping always happens at the high end, but clipping at the bottom is
>> kind of optional.
>
>But that is exactly what they do with the in camera jpegs, they clip the top
>and bottom to fit within the contrast range set. IMHO the sensors aren't
>good enough right now to worry too much about 12bit being an issue.


It is important when scanning film.
July 10, 2005 5:01:33 PM

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

Jeremy Nixon wrote:

> Stacey <fotocord@yahoo.com> wrote:
>> JPS@no.komm wrote:
>>
>>> Clipping always happens at the high end, but clipping at the bottom is
>>> kind of optional.
>>
>> But that is exactly what they do with the in camera jpegs, they clip the
>> top and bottom to fit within the contrast range set.
>
> Right. Now, what if you don't want it to clip at the top, but don't care
> as
> much about the bottom? Or vice-versa? Or what if you really do care
> about
> both, but aren't concerned about the midtones? The "default" algorithm is
> a general case and can't take into account the needs of a particular
> image.
>

Which is why we shoot RAW! :-) But you already knew that part.

--

Stacey
Anonymous
July 10, 2005 8:25:35 PM

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

In message <3jbmpgFp7kbrU1@individual.net>,
Stacey <fotocord@yahoo.com> wrote:

>JPS@no.komm wrote:

>> Clipping always happens at the high end, but clipping at the bottom is
>> kind of optional.

>But that is exactly what they do with the in camera jpegs, they clip the top
>and bottom to fit within the contrast range set.

They may clip the bottom, but it is not necessary, to achieve the
mapping. The deepest shadows are often clipped or sharply compressed to
hide noise in the shadows, not to make it fit, per se. The histogram is
not symmetrical; There is nothing to the left of zero; there are
potential highlights to the right of the histogram's highest level.

>IMHO the sensors aren't
>good enough right now to worry too much about 12bit being an issue.

Nope. ISO 100 dynamic range in DSLRs is limited by the 12-bit
digitization, not the noise. I estimate about 2 or 3 more highly-usable
stops with finer digitization.

This is easily proven by taking a shot at the camera's highest ISO, a
shot that has shadow detail, and then leave the shutter speed and the
f-stop right where they are, and taking the same shot with the ISO
reduced to the camera's lowest. Bring them both to the same output
tonal levels in the RAW conversion, and see how much more detail the
high-ISO image has.
--

<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
John P Sheehy <JPS@no.komm>
><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
Anonymous
July 10, 2005 8:27:34 PM

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

In message <11d1mridnqij73e@corp.supernews.com>,
Jeremy Nixon <jeremy@exit109.com> wrote:

>On the contrary, their capabilities (at least at low ISO) seem to be
>limited by the 12-bit data representation rather than the sensor itself.
>I say that not knowing the first thing about A/D converter design,
>though, so it's really easy for me to say "use a 16 bit conversion"
>when I have no idea what technical barriers prevent that from happening.

The answer is not in a black box; just compare a high-ISO shot with
shadow details to the same f-stop and shutter speed at the lowest ISO.
If you can see anything extra in the high-ISO shot, the sensor is being
under-digitized at ISO 100.
--

<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
John P Sheehy <JPS@no.komm>
><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
Anonymous
July 11, 2005 3:32:36 AM

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

DonB <oink@woosh.co.nz> wrote:

>If you like to spend lots of time to get your image perfect in your
>eyes, RAW is for you. If you just want excellent images, high quality
>JPEGS are fine.
>If you showed an expert 2 different images, he would be guessing to say
>which was RAW,

That's only true if the JPG was shot with the optimal settings for
(foremost among other things) contrast and white balance.

With JPG it's vital you choose the right white balance setting
at shooting, since there is little you can do to correct later
without skewing the pic horribly. Similarly, if you don't get
the contrast right, you can end up with shot-out highlights and
no detail in the dark bits.

I find that trying to keep all these variables in mind while
shooting makes JPG a true pain-in-the-arse. I already have
enough to think about with composition, f/shutter and zoom/framing.

If you shoot raw, it's an advantage to have a reference white balance
shot, but it isn't necessary. The contrast setting also doesn't
matter a bit, since you can change all those things after the fact
for best performance. It frees up your mind and time during shooting
to capture the subject at the right instant. That's the primary
reason to choose RAW, IMO.

--
Ken Tough
!