"16-bit" mode.

In article , Mike
Russell wrote:

Mike Engles wrote:
...
[re linear encoding of specialized pixel data values]

Is the same true for imaging from spacecraft, interplanetary or
otherwise or is gamma encoding done before transmission?

Yes. Gama encoding compresses some data values, and there is no reason to
do this to raw data from a spacecraft.

Here's an article that may interest you, by Alvy Ray Smith, on the
distinction of work and display color spaces.
http://alvyray.com/Memos/MemosMicros...rAlphaQuestion

Actually, Alvy has a number of mistakes in that paper.
I'm still not sure if he understands gamma encoding...

Chris

In article , Mike
Russell wrote:

Mike Engles wrote:
...
[re linear encoding of specialized pixel data values]

Is the same true for imaging from spacecraft, interplanetary or
otherwise or is gamma encoding done before transmission?

Yes. Gama encoding compresses some data values, and there is no reason to
do this to raw data from a spacecraft.

Here's an article that may interest you, by Alvy Ray Smith, on the
distinction of work and display color spaces.
http://alvyray.com/Memos/MemosMicros...rAlphaQuestion

Actually, Alvy has a number of mistakes in that paper.
I'm still not sure if he understands gamma encoding...

Chris

In article , Mike
Russell wrote:

OTOH, Adobe's weird 16 bit format makes it more difficult to interface to
other graphics libraries, requiring additional passes to convert to and from
16 bit mode.

That's why the external representation is 0..65535.
Only the filter plugin APIs have to deal with the 0..32768
representation. There are flags for the file format, import, and
export plugin APIs to use different maximum values (which Photoshop
will then rescale to it's internal representation).

Chris

In article , Mike
Russell wrote:

OTOH, Adobe's weird 16 bit format makes it more difficult to interface to
other graphics libraries, requiring additional passes to convert to and from
16 bit mode.

That's why the external representation is 0..65535.
Only the filter plugin APIs have to deal with the 0..32768
representation. There are flags for the file format, import, and
export plugin APIs to use different maximum values (which Photoshop
will then rescale to it's internal representation).

Chris

In message ,
Chris Cox wrote:

In article ,
wrote:

In message ,
Chris Cox wrote:

Without your original data to test, I can't even guess what went wrong.

You don't need my original data.

Any image in "16 bit greyscale" mode has all kinds of numbers between 0
and 32768 missing,

Only if you started with an image that had numbers missing.
The representation is 0..32768 -- all numbers are possible.


and not possible no matter hown much you blur or
interpolate. "16 bit greyscale" is about 13.5 bit greyscale.

No, that is not even remotely correct.

It is exactly what is happening here. I get 0, 1, 3, 4, 5, 8, etc. No
2, 6, 7, 11, etc, at all, no matter what is done to the data. That's
with color management disabled. With it enabled, I had even less
values. Clusters of 6 16-bit numbers all became the same "15bit+1"
value when color management was enabled (except 3 values became 0, and 3
values became 32768).

I could write this off to a corrupted executable, but it happens on two
different installations of CS.
--


John P Sheehy

In message ,
Chris Cox wrote:

In article ,
wrote:

In message ,
Chris Cox wrote:

Without your original data to test, I can't even guess what went wrong.

You don't need my original data.

Any image in "16 bit greyscale" mode has all kinds of numbers between 0
and 32768 missing,

Only if you started with an image that had numbers missing.
The representation is 0..32768 -- all numbers are possible.


and not possible no matter hown much you blur or
interpolate. "16 bit greyscale" is about 13.5 bit greyscale.

No, that is not even remotely correct.

It is exactly what is happening here. I get 0, 1, 3, 4, 5, 8, etc. No
2, 6, 7, 11, etc, at all, no matter what is done to the data. That's
with color management disabled. With it enabled, I had even less
values. Clusters of 6 16-bit numbers all became the same "15bit+1"
value when color management was enabled (except 3 values became 0, and 3
values became 32768).

I could write this off to a corrupted executable, but it happens on two
different installations of CS.
--


John P Sheehy

On Mon, 22 Nov 2004 00:07:44 GMT, Chris Cox
wrote:


This is still a problem.
When 64 bit processors become the norm (and the @#!^&$ OS allows a
fully 64 bit application), then that becomes less of a problem.

Is a 64 bit optimised Photoshop likely to be faster, or just more able
to do complex operations? Or do the programmers generally aim for a
bit of both if you'll pardon the pun

--

Hecate - The Real One

veni, vidi, reliqui

In article ,
wrote:

In message ,
Chris Cox wrote:

In article ,
wrote:

In message ,
Chris Cox wrote:

Without your original data to test, I can't even guess what went wrong.

You don't need my original data.

Any image in "16 bit greyscale" mode has all kinds of numbers between 0
and 32768 missing,

Only if you started with an image that had numbers missing.
The representation is 0..32768 -- all numbers are possible.


and not possible no matter hown much you blur or
interpolate. "16 bit greyscale" is about 13.5 bit greyscale.

No, that is not even remotely correct.

It is exactly what is happening here. I get 0, 1, 3, 4, 5, 8, etc. No
2, 6, 7, 11, etc, at all, no matter what is done to the data.

And, again, without your original data - I can't guess what could have
gone wrong.

I do know that for anyone else doing a similar experiment (inside and
outside Adobe), they get the full 32769 values.

Chris

In article ,
wrote:

In message ,
Chris Cox wrote:

In article ,
wrote:

In message ,
Chris Cox wrote:

Without your original data to test, I can't even guess what went wrong.

You don't need my original data.

Any image in "16 bit greyscale" mode has all kinds of numbers between 0
and 32768 missing,

Only if you started with an image that had numbers missing.
The representation is 0..32768 -- all numbers are possible.


and not possible no matter hown much you blur or
interpolate. "16 bit greyscale" is about 13.5 bit greyscale.

No, that is not even remotely correct.

It is exactly what is happening here. I get 0, 1, 3, 4, 5, 8, etc. No
2, 6, 7, 11, etc, at all, no matter what is done to the data.

And, again, without your original data - I can't guess what could have
gone wrong.

I do know that for anyone else doing a similar experiment (inside and
outside Adobe), they get the full 32769 values.

Chris

In article , Hecate
wrote:

On Mon, 22 Nov 2004 00:07:44 GMT, Chris Cox
wrote:


This is still a problem.
When 64 bit processors become the norm (and the @#!^&$ OS allows a
fully 64 bit application), then that becomes less of a problem.

Is a 64 bit optimised Photoshop likely to be faster, or just more able
to do complex operations? Or do the programmers generally aim for a
bit of both if you'll pardon the pun


That depends a lot on the CPU in question, and the operation in
question.
Most likely there will be little performance difference, but a big
difference in available RAM (addressibility).

Chris