About wide vs. small gamuts, 8 vs. 16-bit &sRGB vs. Adobe'98

Started Apr 3, 2003 | Discussions
Frank B Veteran Member • Posts: 5,410
Thanks extremely helpful. (NT)

Thanks.

Frank B

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firekat Forum Member • Posts: 70
Re: Photoshop 16-bit...

Try Picture Window Pro. You can manipulate images of varying bit depths right up to 48 bit. It does not have the full functionality that Photoshop has, as it is built mostly to deal with photograpic images. It is quite a capable program in it's own right and it is pretty fast and straight forward. There is also a major upgrade in the works that should be forthcoming in the near future.

See http://www.dl-c.com/ for more details.

Magne Nilsen wrote:

Mishkin wrote:

Photoshop's 16-bit SUCKS!!! You can't have layers, you can do
almost nothing but some color adjustments.... Ugh!!!

It obviously takes Adobe a lot of time to enable 16-bit for a wider
set of the functions, but at least some of my favorites are in
place. For full image editing Curves and Levels are fully there,
and I tend to do > 2/3 of my work in Curves. Segmented editing
seems worse unless you can live with Marquees and Lassos to make
selections. I tend to make a 8-bit copy of my 16-bit image, create
and then Save my selections there, and then from the 16-bit image
use "Load Selection" from the 8-bit image. Works fine for me. As
for the filters, well there is Gaussian Blur, Median and Unsharp
Mask. Hmmm, that is about the only filters I use for image
correction and editing, so I don't really care. If you must have
the rest of the filters, you have to switch into 8-bit - yes, but I
find that most of them are more on the artistic side, and seldom
use them. What I really miss is cut & paste, layers and transform...

~~~~
Magne

Ranjan Senior Member • Posts: 1,248
Need to rethink my work flow

Quite a good usefull discussion.

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Ranjan
Professional photographer.
http://www.photosig.com/go/users/view?id=11993

feivel Forum Pro • Posts: 10,168
FINALLY, I understand!

how about stopping by the retouching forum once in a while and straightening us out

feivel

Paul S. R. Regular Member • Posts: 362
Re: Thanks for the primer, Magne, and one gripe:

Photoshop 8 is supposed to fix this limitation.

Can't wait for it to come out!

Paul S. R.

Mishkin wrote:
Photoshop's 16-bit SUCKS!!! You can't have layers, you can do
almost nothing but some color adjustments.... Ugh!!!

Magne Nilsen wrote:

(This is an early preview of an article that soon will appear on
the http://www.etcetera.cc site)

Leonardo Contributing Member • Posts: 695
Re: FINALLY, I understand!

feivel,

Since you understandand, maybe you can enlighten me about this 16 bit business. When in RGB (a or s) mode, is the in-camera file saved as 16 or 8 bit? If its saved as 16 bit, then it would seem wise, from what was said above, to postprocess in 16 bit mode, if possible. But what if its saved as 8 bit in camera????

And how does Raw fit into the 8 vs 16 bit discussion. I read, above, that it is saved with 24 bits in camera. Is that correct?

A few months ago I asked you to help my niece, and you did. Now its time to help me.

Leonardo

feivel wrote:

how about stopping by the retouching forum once in a while and
straightening us out

feivel

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FCAS Member, CP5000
Leonardo

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David Barker Senior Member • Posts: 2,966
Re: FINALLY, I understand!

Leonardo wrote:

... maybe you can enlighten me about this 16
bit business. When in RGB (a or s) mode, is the in-camera file
saved as 16 or 8 bit? If its saved as 16 bit, then it would seem
wise, from what was said above, to postprocess in 16 bit mode, if
possible. But what if its saved as 8 bit in camera????

I think it depends what file type you have chosen for your in-camera images. If you save as jpeg the camera converts down to 8 bit prior to saving.

And how does Raw fit into the 8 vs 16 bit discussion. I read,
above, that it is saved with 24 bits in camera. Is that correct?

Most RAW-capable cameras seem to save 12 data bits (per colour channel). That's why it's often recommended to work in 16 bit depth (although 12 would be adequate, that's not on offer!). As you imply in your question it would be a waste of time and storage space to save 8 bit images in 16 bit data files.

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David Barker

Diane B Forum Pro • Posts: 20,629
Always worth reading your posts....

Magne Nilsen wrote:

(This is an early preview of an article that soon will appear on
the http://www.etcetera.cc site)

With the many discussion appearing lately about colors, color
spaces, 8-bit vs. 16-bit and sRGB vs. Adobe RGB (1998), there seem
to be as many preferences as there are combinations, and most
proponents of one versus the other often seems more confused than
the other. I have a feeling that some perspective could be needed.
It is not too hard to understand most of this, so...

This is an honest attempt to set some basic terms straight.

I will reread this again--as well as read the complete thread. I'm wondering how I missed this one and just saw it for the first time.
]

There was a raging discussion on the Epson 2200 maillist about this, then a lot of discussion on Rob Galbraith (I know you posted there--perhaps that thread prompted this one). I even tried PHotopro as a working space after that one LOL. However, I've 'reverted' to ARGB98--but I NOW work almost completely in 16 bit after upgrading to PSCS. I felt limited in PS7, but tried to do as much s possible. Your great demo has convinced me that it definitely is worthwhile.

And--now to read the rest of the thread. BTW--how did you get so smart about color, color spaces, profiles, etc. LOL????

Diane
--
Diane B
http://www.pbase.com/picnic/galleries
B/W lover, but color is seducing me

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David Barker Senior Member • Posts: 2,966
That's why...

Diane B wrote:

I will reread this again--as well as read the complete thread. I'm
wondering how I missed this one and just saw it for the first time.

It seemed such a worthwhile thread that I didn't hesitate to bump it back into currency.

(Oops - just done so again.)

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David Barker

Diane B Forum Pro • Posts: 20,629
Just realized....

David Barker wrote:

Diane B wrote:

I will reread this again--as well as read the complete thread. I'm
wondering how I missed this one and just saw it for the first time.

It seemed such a worthwhile thread that I didn't hesitate to bump
it back into currency.

(Oops - just done so again.)

-- hide signature --

David Barker

the date of the thread. I expect I did read this last Spring LOL. I always read Magne's posts. I am a big proponent of his D60/30 profiles for C1LE. But---its -probably a good thing you bumped it because there are a lot of new folks on the forum that don't quite understand color management.

I REALLY need to check dates of posts before I reply LOL.

Diane
--
Diane B
http://www.pbase.com/picnic/galleries
B/W lover, but color is seducing me

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Jason Hutchinson Forum Pro • Posts: 12,177
until you edit it

David Barker wrote:

Most RAW-capable cameras seem to save 12 data bits (per colour
channel). That's why it's often recommended to work in 16 bit depth
(although 12 would be adequate, that's not on offer!).

It's worth noting that one of the points of the original post is that 12 bits would no longer be enough as soon as you applied (for instance) and S curve to the 12 bit RAW image in a 12 bit image editor. As a matter of fact simple bayer interpolation of a 12 bit image would likely create levels between the original 12 bits.

Jason

David Barker Senior Member • Posts: 2,966
Re: until you edit it

Jason Hutchinson wrote:

David Barker wrote:

Most RAW-capable cameras seem to save 12 data bits (per colour
channel). That's why it's often recommended to work in 16 bit depth
(although 12 would be adequate, that's not on offer!).

It's worth noting that one of the points of the original post is
that 12 bits would no longer be enough as soon as you applied (for
instance) and S curve to the 12 bit RAW image in a 12 bit image
editor. As a matter of fact simple bayer interpolation of a 12 bit
image would likely create levels between the original 12 bits.

I was really being slightly flippant about the bit-depth; superficially it seems odd to have the option of using 8 or 16 bit files to accommodate 12 bits of data. I take your point.

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David Barker

Jason Hutchinson Forum Pro • Posts: 12,177
Re: until you edit it

David Barker wrote:

I was really being slightly flippant about the bit-depth;
superficially it seems odd to have the option of using 8 or 16 bit
files to accommodate 12 bits of data. I take your point.

Agreed... sort of like have 32 bits being used toward 24 bits of color.

Jason

bee1000 Regular Member • Posts: 471
Thank you

Thank you for spending the time to put this together, I am impressed by the results and a appreciative of your efforts.

I think I understand the various parts of your thread, and have tried to explain them to others, but your thread puts everything in one place.

Until it comes time to explain how the theory evolves into practice, at least!

Thank you very much, I look forward to seeing (and bookmarking) the full article.

Magne Nilsen wrote:

(This is an early preview of an article that soon will appear on
the http://www.etcetera.cc site)

With the many discussion appearing lately about colors, color
spaces, 8-bit vs. 16-bit and sRGB vs. Adobe RGB (1998), there seem
to be as many preferences as there are combinations, and most
proponents of one versus the other often seems more confused than
the other. I have a feeling that some perspective could be needed.
It is not too hard to understand most of this, so...

snip

~~~~
Magne

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Jim Dawson Veteran Member • Posts: 3,802
Tag (NT)

bee1000 wrote:
Thank you for spending the time to put this together, I am
impressed by the results and a appreciative of your efforts.

I think I understand the various parts of your thread, and have
tried to explain them to others, but your thread puts everything in
one place.

Until it comes time to explain how the theory evolves into
practice, at least!

Thank you very much, I look forward to seeing (and bookmarking) the
full article.

Magne Nilsen wrote:

(This is an early preview of an article that soon will appear on
the http://www.etcetera.cc site)

With the many discussion appearing lately about colors, color
spaces, 8-bit vs. 16-bit and sRGB vs. Adobe RGB (1998), there seem
to be as many preferences as there are combinations, and most
proponents of one versus the other often seems more confused than
the other. I have a feeling that some perspective could be needed.
It is not too hard to understand most of this, so...

snip

~~~~
Magne

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Canon 1D Mark II, Pentax Optio 555, and G-III QL (yes - film)

Louis4444 Veteran Member • Posts: 3,169
Confirms Rule Of Thumb...

(This is an early preview of an article that soon will appear on
the http://www.etcetera.cc site)

Nice work. You illustrate my old rule of thumb that one can basically take two routs: 16-bit (=12-bit RAW) and large gamut spaces (=AdobeRGB), and 8-bit (=JPG) and sRGB (=small gamut space).

Donald Cooper Veteran Member • Posts: 4,927
Very relevant for 20D, needs a bump (nt)

Magne Nilsen wrote:

(This is an early preview of an article that soon will appear on
the http://www.etcetera.cc site)

With the many discussion appearing lately about colors, color
spaces, 8-bit vs. 16-bit and sRGB vs. Adobe RGB (1998), there seem
to be as many preferences as there are combinations, and most
proponents of one versus the other often seems more confused than
the other. I have a feeling that some perspective could be needed.
It is not too hard to understand most of this, so...

This is an honest attempt to set some basic terms straight. The
accompanying illustrations are made to perceptually convey what is
discussed, and are not meant to be scrutinized by their byte
values. They are for 'your eyes only'.

Let's simplify a little. The example above shows two gamuts. A
gamut is all the colors that can be reproduced or captured by a
device. The number of bits used to hold the gamut dictates the
number of steps that each color can contain. Many bits will give
room for many subtle variations or tones per color. The width of
the gamut puts constraints upon, or limits the saturation level of
colors inside the gamut. A wide gamut can hold very saturated
colors, while a small gamut will sacrifice those most vivid colors.
As long as the gamut is, and stays, both wide and has many bits to
represent the color values, few problems should occur in handling
images. As you see from the illustration above, the "large gamut"
version has more saturated blues, greens, reds, yellows etc. Why
would anyone consider the "small gamut" version at all?

These are the same gamuts as in the first image, but this time
represented with fewer bits. The large gamut version still has more
saturated colors, but now there is a price to pay! The "few-bits
large gamut" has sacrificed many of the more subtle tonalities to
give room for the more saturated and neon-like colors. Which finite
set of the colors above do you think would be the best to
accurately describe human skin, like in a portrait? Or - a sunset?
Or - a small lake with a green forest around?
These illustrations are much worse than the difference between
8-bit vs. 16-bit, and sRGB vs. Adobe RGB (1998), but this is still
the dilemma you are going to face in the real world of printers and
output devices. Sooner or later.
At some stage the "many-bits large gamut" image must be color-wise
transformed into a "not-so-wide" and "not-so-many-bits" gamut,
representing a display, a web page or a printer. Printer gamuts are
actually mostly smaller than sRGB.
At some stage you will be doing things in 8-bit software as well.
Photoshop has some limitations on the available functionality for
16-bit images, but I would still advice all to switch to 16-bit as
soon as possible, and stay there as long as possible when editing
images. When you go from “wide gamut 16-bit” to “small gamut 8-bit”
you should know what will happen, or you could be in for a
surprise, or even worse, your customer/client/uncle could be in for
a color-wise surprise.

As an example on how bad things can get, look at the last
illustration.

Applying an S-curve as strong as the one above onto the prior shown
“few-bits large gamut” image will result in a reduction from 400
finite colors down to 300. 100 colors (25% of the gamut!) will be
gone, and many colors will show up as identical in the image. The
same thing would happen if we were to show a “few-bits huge gamut”
image on your “not so huge gamut” display. You would not be able to
discern many of the colors from each other at all.

My intention with this is not to scare anyone away from using a
wide gamut working space to hold or edit their images. My advice
would be to check up what exact colors you are getting in Adobe RGB
1998 that are not present in sRGB and vice versa. I think you could
be surprised.

16-bit editing is almost without an exception an advantage.
Especially if you are going to use a wider gamut like Adobe 1998
RGB (or maybe even wider?). You will have a much bigger latitude in
you editing operations before you start to experience ugly 8-bit
problems like banding of neighboring colors, or posterization
problems in the shadows or in skies. Switching to, and staying in
16-bit as long as possible, is almost always an advantage for your
images. I think 16-bit is much more important than using Adobe RGB
1998 as a working space, but I constantly find professionals that
have heard that Adobe RGB 1998 is so good, but they still do all
their editing in 8-bit, and wonder why they have banding and
posterization problems. Most of them believe that this would be
even worse if they had sRGB as their working space, while the
opposite is true. I hope that became clear with the prior
illustrations.

Ah well, 16-bit is “better” than 8-bit then, but wide gamut is not
“better” than small gamut, although the words wide and small for
many would indicate so. It really depends. On the destination
target, on the software available, on your skills and knowledge, on
your input device/monitor/output devices level of quality,
calibration and exactness, and on a few physical truths like
bandwidth, memory, processor and hard disk size and quality. In
many cases it is actually an advantage to be working in a
“not-so-wide” gamut like sRGB. You get more subtle transitions at
the cost of some “neons”, and you will be much less surprised or
disappointed when transferring your images to the web, the printer,
the lab, the clients or your friends.

~~~~
Magne

Kaustav S Saikia
Kaustav S Saikia Contributing Member • Posts: 672
excellent article,
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