Date   

ftp site ready

Jeremy Selan <jeremy...@...>
 

We've now got an ftp site setup at spi for large file posting. If you
want to post files > 10MB email me and I'll send you the login info.


Re: Lut format chart

Jeremy Selan <jeremy...@...>
 

Exactly. Clients apps will automatically have support for all lut
formats. (It's about time!)

To an end user, this should feel pretty automated. Apps shouldn't
need ebd user options / dialogs, all of the lut-location mojo is
internal to the ColorConfiguration file.

Specifying which configuration to use is controlled via a single
environment variable (which points at an ocs file). (Explicit
initialization is also allowed, but this will probably be less
common).

The internals of the .ocs file are still in flux, but the rough idea
is that there will be two flavors. One flavor will be a human-
readable xml file, of which one element lut dir. The alternative will
be a binary ocs 'package', where the lut dir is self contained in the
file. (Think tgz of a config / lut dir).

In the super common newbie-case, downloading a single .ocs binary
file, and pointing to it with OCS_CONFIG will be all that's needed.

-- Jeremy

On May 25, 3:09 pm, Larry Gritz <l....@imageworks.com> wrote:
Neat.  So just to clarify, the big idea is that any app that uses your color library properly will, by extension, understand ALL of these luts (whichever happens to be available/used at the facility using the app)?

Just how automated can this be?  I'm a little unclear on how much extra homework a display program needs to do.  Will your library... um... just find the lut specs in whatever standard places they are stored and know how to correct images for proper display on that device?  Are there standard places for the luts to be stored?  Will an app need various user options/dialogs to set this up?  Is this too much of a newbie question?

On May 25, 2010, at 2:51 PM, Jeremy Selan wrote:

Blake was kind enough to a google doc spreadsheet of lut formats:
http://spreadsheets.google.com/ccc?key=0Avn2cZhY9jaYdF9qTHYteU1MUDYtd...
I'll try to edit it to keep it up to date.  (what formats we support,
are planning to support, have examples of, etc). And eventually it'll
probably turn into part of the ocs website.
--
Larry Gritz
l....@imageworks.com


Re: [ocs-dev] Lut format chart

Larry Gritz <l...@...>
 

Neat. So just to clarify, the big idea is that any app that uses your color library properly will, by extension, understand ALL of these luts (whichever happens to be available/used at the facility using the app)?

Just how automated can this be? I'm a little unclear on how much extra homework a display program needs to do. Will your library... um... just find the lut specs in whatever standard places they are stored and know how to correct images for proper display on that device? Are there standard places for the luts to be stored? Will an app need various user options/dialogs to set this up? Is this too much of a newbie question?


On May 25, 2010, at 2:51 PM, Jeremy Selan wrote:

Blake was kind enough to a google doc spreadsheet of lut formats:
http://spreadsheets.google.com/ccc?key=0Avn2cZhY9jaYdF9qTHYteU1MUDYtdnFkSDJQdHpaU1E&hl=en

I'll try to edit it to keep it up to date. (what formats we support,
are planning to support, have examples of, etc). And eventually it'll
probably turn into part of the ocs website.
--
Larry Gritz
l...@imageworks.com


Lut format chart

Jeremy Selan <jeremy...@...>
 

Blake was kind enough to a google doc spreadsheet of lut formats:
http://spreadsheets.google.com/ccc?key=0Avn2cZhY9jaYdF9qTHYteU1MUDYtdnFkSDJQdHpaU1E&hl=en

I'll try to edit it to keep it up to date. (what formats we support,
are planning to support, have examples of, etc). And eventually it'll
probably turn into part of the ocs website.


Re: Got Luts?

Jeremy Selan <jeremy...@...>
 

Thanks!

I do have the houdini docs, but if you could send me known good
examples luts that would be helpful as well.
If the files are small (under 10 MB) just post them to this as files
to this group.

I am setting up an ftp site today, which will have a first code drop
as well as allow folks to post larger luts / images as needed.

-- Jeremy

On May 25, 7:55 am, Mark Alexander <malex...@sidefx.com> wrote:
I can send the specs for the Houdini .lut (ASCII) and .blut (bin)
formats, if you need that. They're also in the HDK documentation, if
you have access to that.


[ocs-dev] Re: Got Luts?

Mark Alexander <malex...@...>
 

I can send the specs for the Houdini .lut (ASCII) and .blut (bin)
formats, if you need that. They're also in the HDK documentation, if
you have access to that.


[ocs-dev] Re: Got Luts?

Jeremy Selan <jeremy...@...>
 

Ah, there is a 10MB per-file limit to uploads on google groups. Let
me whip up an alternative...

On May 24, 9:15 am, Bruno Nicoletti <bruno.j....@googlemail.com>
wrote:
80 Megs or so of data seems to have confused Google.

Anyother way?

b


Re: [ocs-dev] Got Luts?

Bruno Nicoletti <bruno.j....@...>
 

80 Megs or so of data seems to have confused Google.

Anyother way?

b

On 24 May 2010 10:59, Bruno Nicoletti <bruno.j....@googlemail.com> wrote:
Hi Jeremy,

these are the ones we support in Nuke...

.vf     Nuke native vector field
vfz    gzip compressed .vf files
.cub(e)    Truelight 1D or 3D LUT
.cube    Iridas LUT
.csp    Cinespace LUT
.3dl    Autodesk/Scratch LUT
.blut    Houdini mplay blut

I can get you example files

b

On 21 May 2010 22:35, Jeremy Selan <jeremy...@gmail.com> wrote:
Hello!

I'm at the stage where I would like to get a survey of lut file
formats (1d, 3d, matrix, etc) that folks actually use in the wild.

If you commonly use a lut format at your facility, or define one in
your software package, I would hugely appreciate it if you could
upload example files and/or spec documents so I can begin work on the
importers.

Even if it's a proprietary format, I'd love to take a peek so I can
get a sense of the scope of formats out in the wild.  (I need to make
sure the internal API is rich enough to encompass current use cases).

Many formats have been mentioned previously, including:
   - Truelight ASCII .cub 3D lut
   - Assimilate Scratch  (Arri /Kodak .3dl)
   - Iridas Framecycler  (Iridas .cube)
   - Autodesk            (MESH3D, .lut, etc.)

For the majority of these, I do not have either example files or
specifications. Please help! :)

Also, does anyone know if the majority of lut formats identifiable by
their extension?  Are there common extension conflicts?  Ideally, I'd
like to try and have format reader registered based on file extension,
and only if that fails give each lut loader a chance to read it.
(Similar to how reader plugins work in nuke).

(Note that I'm not assuming 1 file == 1 lut.  (We will support readers
where 1 file can generate multiple transforms, such as a 1d shaper lut
-> 3d lut -> 1d shaper lut.))


--
Bruno Nicoletti
--
Bruno Nicoletti


Re: [ocs-dev] Got Luts?

Bruno Nicoletti <bruno.j....@...>
 

Hi Jeremy,

these are the ones we support in Nuke...

.vf Nuke native vector field
vfz gzip compressed .vf files
.cub(e) Truelight 1D or 3D LUT
.cube Iridas LUT
.csp Cinespace LUT
.3dl Autodesk/Scratch LUT
.blut Houdini mplay blut

I can get you example files

b

On 21 May 2010 22:35, Jeremy Selan <jeremy...@gmail.com> wrote:
Hello!

I'm at the stage where I would like to get a survey of lut file
formats (1d, 3d, matrix, etc) that folks actually use in the wild.

If you commonly use a lut format at your facility, or define one in
your software package, I would hugely appreciate it if you could
upload example files and/or spec documents so I can begin work on the
importers.

Even if it's a proprietary format, I'd love to take a peek so I can
get a sense of the scope of formats out in the wild.  (I need to make
sure the internal API is rich enough to encompass current use cases).

Many formats have been mentioned previously, including:
   - Truelight ASCII .cub 3D lut
   - Assimilate Scratch  (Arri /Kodak .3dl)
   - Iridas Framecycler  (Iridas .cube)
   - Autodesk            (MESH3D, .lut, etc.)

For the majority of these, I do not have either example files or
specifications. Please help! :)

Also, does anyone know if the majority of lut formats identifiable by
their extension?  Are there common extension conflicts?  Ideally, I'd
like to try and have format reader registered based on file extension,
and only if that fails give each lut loader a chance to read it.
(Similar to how reader plugins work in nuke).

(Note that I'm not assuming 1 file == 1 lut.  (We will support readers
where 1 file can generate multiple transforms, such as a 1d shaper lut
-> 3d lut -> 1d shaper lut.))
--
Bruno Nicoletti


Re: [ocs-dev] Got Luts?

"Nathaniel Hoffman" <na...@...>
 

Jeremy,

There are two LUT formats I know of that are used in game development.

One is a 2D image format (any lossless image format will do - we've used
BMP, TGA and PNG) with a 2D representation of the LUT where the planes
along the 3rd axis have been placed next to each other. So a 32x32x32 LUT
would turn into a 1024x32 2D image. A common usage is for an identity LUT
in this format to be placed next to an ungraded screenshot, both
manipulated in Photoshop or some other color manipulation package, and
then the colorized LUT is extracted.

The other format is a DDS (Microsoft DirectDraw Surface) file with a 3D
texture in it, typically uncompressed. This is usually loaded directly
into the game engine.

These are both a bit ad-hoc and not really standardized, so I don't know
if they are relevant for OCS. If they are, let me know and I can try to
work up something more like an actual spec for each of these.

Thanks,

Naty

Hello!

I'm at the stage where I would like to get a survey of lut file
formats (1d, 3d, matrix, etc) that folks actually use in the wild.

If you commonly use a lut format at your facility, or define one in
your software package, I would hugely appreciate it if you could
upload example files and/or spec documents so I can begin work on the
importers.

Even if it's a proprietary format, I'd love to take a peek so I can
get a sense of the scope of formats out in the wild. (I need to make
sure the internal API is rich enough to encompass current use cases).

Many formats have been mentioned previously, including:
- Truelight ASCII .cub 3D lut
- Assimilate Scratch (Arri /Kodak .3dl)
- Iridas Framecycler (Iridas .cube)
- Autodesk (MESH3D, .lut, etc.)

For the majority of these, I do not have either example files or
specifications. Please help! :)

Also, does anyone know if the majority of lut formats identifiable by
their extension? Are there common extension conflicts? Ideally, I'd
like to try and have format reader registered based on file extension,
and only if that fails give each lut loader a chance to read it.
(Similar to how reader plugins work in nuke).

(Note that I'm not assuming 1 file == 1 lut. (We will support readers
where 1 file can generate multiple transforms, such as a 1d shaper lut
-> 3d lut -> 1d shaper lut.))


[ocs-dev] Got Luts?

Jeremy Selan <jeremy...@...>
 

Hello!

I'm at the stage where I would like to get a survey of lut file
formats (1d, 3d, matrix, etc) that folks actually use in the wild.

If you commonly use a lut format at your facility, or define one in
your software package, I would hugely appreciate it if you could
upload example files and/or spec documents so I can begin work on the
importers.

Even if it's a proprietary format, I'd love to take a peek so I can
get a sense of the scope of formats out in the wild. (I need to make
sure the internal API is rich enough to encompass current use cases).

Many formats have been mentioned previously, including:
- Truelight ASCII .cub 3D lut
- Assimilate Scratch (Arri /Kodak .3dl)
- Iridas Framecycler (Iridas .cube)
- Autodesk (MESH3D, .lut, etc.)

For the majority of these, I do not have either example files or
specifications. Please help! :)

Also, does anyone know if the majority of lut formats identifiable by
their extension? Are there common extension conflicts? Ideally, I'd
like to try and have format reader registered based on file extension,
and only if that fails give each lut loader a chance to read it.
(Similar to how reader plugins work in nuke).

(Note that I'm not assuming 1 file == 1 lut. (We will support readers
where 1 file can generate multiple transforms, such as a 1d shaper lut
-> 3d lut -> 1d shaper lut.))


[ocs-dev] Re: Foundry Questions

Jeremy Selan <jeremy...@...>
 

Sorry for the delay!

Progress on the library is going well, I hope to have a code drop
ready in the next few weeks.

To answer your latest few questions...


These reference various .spiXXX files, are you going to open up the
format of those files?
Yes and no. We're going to open up the formats in the sense that the
library will have a built-in reader support (The format details are
incredibly uninteresting; just another brain-dead ascii text format).
However, we're not going to push for anyone else to adopt them.
Internally, once we get support for commercial lut formats we'll
probably try to retire the spi formats.


I suppose what we are missing are use cases of the library in
practice. I have a pretty good guess as to how it would work at big
film houses, film houses collaborating and film houses sharing work
with smaller shops, but clear descriptions of that would be great.

I guess my major concern is that if The Foundry is using this as the
basis of a cross product CMS, we still need to make it work for the
small shops in isolation, and they need tools to do at least the basic
stuff that the big boys have in-house specialist do. So display
calibration profiles and so on. Have you had any thoughts as to that?
I'm not really familiar with how small houses (where someone is tasked
only part time) deal with the issue of color management. Maybe we
would ask some contacts at smaller houses for more detail about their
'off the shelf' color pipelines? I think this route would
particularly be worth the effort, as the small houses (who dont have
someone tasked full time to color) would have the most to gain in
having this library succeed.

-- Jeremy


Re: [ocs-dev] Re: Foundry Questions

Bruno Nicoletti <bruno.j....@...>
 

Hi Jeremy,

thanks for the reply. A few more questions....


 - how do you represent
       - transforms
       - display devices
       - looks
Please see the file config_v0.ocs, you will see examples of all 3.
These reference various .spiXXX files, are you going to open up the
format of those files?


 - any open source ones?
What open source lut formats are you referring to?
Little CMS was the one mumbled about here. Not sure how important this
is, need to get back to our folks.

Are you looking at making it extensible?
Not sure what you mean here.  Anyone can add or create a custom
colorspace configuration.  Anyone can take one of the posted
configurations and add new color spaces or devices to it.  And the
whole library will be open source so the internal details wont be
secret.  So,... "yes?"
By some sort of plugin method, you mentioned this in your reply with
respect to proprietary CMS systems.

What level of thread safety is there?
The library is fully thread safe. (and efficient in a multi-thread
context).

I am currently adding the color configuration mutable API, and am
grappling with a few corner issues such as ' what if one thread
manipulates the color configuration while another is processing
pixels?' but this is a mental correctness issue, not a crashing issue.
I'd simply say you couldn't process while manipulating the the configuration.

 - have you thought about OpenCL code generation?
Not yet. Are you interested in opengl?
We are playing with OpenCL and it might be useful to have that at some
point. Not a high priority for us at the moment.


Are you shipping it with any vanilla XFMs that you have created at
Sony?
 - and not just log/lin
 - device profiles?
What's an XFM?  A configuration I presume? (im now calling them .ocs
files)

Yes, we're gonna ship all input device profiles we've got, not just
log/lin.  The only camera we've never characterized is RED, so we'd
have to leave that to someone else. (Or could adapt the nuke one for
use in our environment).

For device profiles the only ones we ever use are srgb, r709, and p3
dlp. These will be included.
Sorry, 'XFM' is my bizarre short hand for 'transform', but that still
answers it.



I suppose what we are missing are use cases of the library in
practice. I have a pretty good guess as to how it would work at big
film houses, film houses collaborating and film houses sharing work
with smaller shops, but clear descriptions of that would be great.

I guess my major concern is that if The Foundry is using this as the
basis of a cross product CMS, we still need to make it work for the
small shops in isolation, and they need tools to do at least the basic
stuff that the big boys have in-house specialist do. So display
calibration profiles and so on. Have you had any thoughts as to that?


--
Bruno Nicoletti


[ocs-dev] Re: Foundry Questions

Jeremy Selan <jeremy...@...>
 

Oh, and one thing to keep in mind; the current version of this library
already works great in Nuke. :)

We've exposed 3 new nodes: ColorSpaceConvert / LogConvert /
DisplayTransform. The 1st two are used in the comp graph natively,
and the final one is used in the Input Process group to do filmlook
conversions. We also have a custom read / write nodes that uses our
color processing instead of the nuke-native processing. All of these
plugins are planned on being open-sourced as well, so right off the
bat we'll have a pretty good workflow example. (And clean example code
on how to do plugin client integration).

Obviously, native application support is the direction we're looking
to head in the long term, but I wanted to clarify that direct
manufacturer support is by no means required for Open Color Space to
be useful at launch.

-- Jeremy


[ocs-dev] Re: Foundry Questions

Jeremy Selan <jeremy...@...>
 

On May 5, 2:30 pm, brunobignose <bruno.j....@googlemail.com>
wrote:

What is you internal representation?
 - we know you want to present this as a black box but we would like
to know some technical details
My discussion of the internals as a 'black' box are meant to be from
the perspective of a simple client application, not from folks
interested in color management or to 'authoring' apps. (Authoring apps
being applications that can generate / introspect into color
configurations).

 - what are the scope of the manipulations, are they all 3D ? Mixed 1D and 3D?
The internal transformations currently include 1D luts / (normal + log
allocation), matrix operations, gamma, 3D lut. They can be arbitrarily
chained and used in the forward or inverse directions (with the
exception of 3d luts, where it is left to use the user to provide an
inverse). We also are adding a group transform, which will be useful
in the API.

 - how do you represent
       - transforms
       - display devices
       - looks
Please see the file config_v0.ocs, you will see examples of all 3.

ColorSpaces are ordered lists of atomic transforms (1d luts, mtx,
gamma, 3d lut, etc). They can be used in any order as many times as
necessary.
DisplayDevices are just labels that define additional blocks of
transforms.
"Looks" are currently a bit in flux. If a look is constant across a
show (even if there are multiple looks), it is typically rolled into
the DisplayDevice block as this is more convenient. Examples of this
would be show-wide 'Warm Look', or "DI Gamut check', etc. If a look
is shot-varying we can use either a single 3dlut or asc color
correction. (However, before release i expect this will get more
general and allow for an arbitrary transform type).

What third party LUTs do you manage?
Currently the list is small, just some internal formats and .3dl
files. But, we hope to support all commercial ascii lut formats
before 1.0

 - any open source ones?
What open source lut formats are you referring to?

 - what happens if a user doesn't have a license for a proprietary lut
library?
It is currently not obvious how we will add support for proprietary
(encrypted) lut formats. Example, truelight. Some companies allow for
the export of ascii luts, but others dont. One workaround would be to
provide a lut plugin interface, so 3rd party color management
companies could write OCS plugins that do the appropriate licence
checks before running a lut transform. A plugin API is probably
outside the scope of a 1.0 release, but could be added to 1.1 without
effecting binary compatibility.

How does one go about generating...
 - LUTs?
Any ways you want. This is not a problem we're looking to solve for
1.0, and is treading deep into philosophical / 'secret sauce' issues.
Internally at SPI, we have a bunch of raw measurement data (such as
film stock profiles, camera exposure sweeps, etc) that guide this
practice. You could make a whole class on this, I'm sure. There are
also a bunch of different philosophies on how this should be done,
many of which are equally valid. My gut feel is that if this project
succeeds, we'll end up with a whole mailing list devoted to this
topic.

Please read the color space comments in this file,
config_v0.ocs

it provides a bit more info.

 - display profiles?
Same as above.

 - looks?
These are typically delivered by DI houses, and are director / DP
guided. If a user is not provided a look by their client, they
probably dont have to worry about one.

 - anything else in there...
Remember that we'll provide a few good default configurations, but I
expect all major facilities to define their own. And, we shouldnt
dictate how they do this. The default configurations wont suck
either, they're really what we use as the starting point for films.

Are you looking at making it extensible?
Not sure what you mean here. Anyone can add or create a custom
colorspace configuration. Anyone can take one of the posted
configurations and add new color spaces or devices to it. And the
whole library will be open source so the internal details wont be
secret. So,... "yes?"


How does this all play with ICC proiles?
We hope to add the ability to export ICC profiles, for lut preview in
tools such as photoshop. Other than that, they are not closely
related. We currently have no intent to add support for reading ICC
profiles.


What level of thread safety is there?
The library is fully thread safe. (and efficient in a multi-thread
context).

I am currently adding the color configuration mutable API, and am
grappling with a few corner issues such as ' what if one thread
manipulates the color configuration while another is processing
pixels?' but this is a mental correctness issue, not a crashing issue.


Invertibility,
 - how guaranteed is that for the general colour transforms?
Color configurations specify whether each operation is invertible or
not. An 'auto' mode is provided for types that are easy to perfectly
invert, but we dont handle 'non-obvious' inversion cases. (i.e., 3d
luts).

Note that our 1D lut processing is really pretty clever (clever in a
good way), and guaranteed to have perfect invertibility. For
example, you can specify a 1d lut that goes from a low dynamic range
allocation to an arbitrary high-dynamic range allocation, and still
get perfect invertibility. We also have a validation script that
prints out info about the current color configuration, this has a step
thats walks through each colorspace and validates perfect
invertibility (flagging otherwise).

 - can you flag invertible transforms in any way?
Yes.

Distributing colour management XML and LUTS
 - have you thought of how to pack XML + LUTS + whatever into a single
file for distribution?
Yes, we're starting to think about it. Internally a directory works
great but we're open to a single file as well. zip or tgz sound
great, we have no preference. I'd probably do a timing check and pick
whichever is faster to decompress live.

 - zip/tgz/voodoo?

OpenGL fragment shaders
 - how do we/you manage any LUTs that need to go along with the
shaders you create?
Only a single 3d lut is needed client side for the shader. The client
is responsible for uploading to the card as necessary, though we
provide a cacheid (cheap to compute) so it can be recomputed /
uploaded as infrequently as possible.

 - have you thought about OpenCL code generation?
Not yet. Are you interested in opengl?

 - we want to be able to supply our own names for objects in generated
code so as to avoid name collision, eg: the function name,
Yes, this is already part of the base api. please see the header.

Note that sidefx has already pointed out that we're going to have to
have finer granularity in our specification of glsl profiles (better
glsl versions), this has yet to be added but will soon.

On going support
 - who is responsible for support?
 - how do we manage folding in fixes?
It's an open source project, so at a minimum I'm responsible for
support. But my hope is that before 1.0 we develop a critical mass
community of those interested who can all work on this 'as developer
equals'. (multiple people having 'root' checkin privileges). I always
get suspicious of open source projects where one person approves all
checkins. My hope is that a few other reputable color folks will step
up and we can all be responsible for validating new code checkins,
etc. Of course, i'll be reading every line of code, but having more
folks on board helps prevent 'hit by bus' scenarios. (or more likely,
'caught in a hard production crunch-time' scenario).

Support on the artist / usage side will be open to a much broader
community, just as nuke-users is.

Are you shipping it with any vanilla XFMs that you have created at
Sony?
 - and not just log/lin
 - device profiles?
What's an XFM? A configuration I presume? (im now calling them .ocs
files)

Yes, we're gonna ship all input device profiles we've got, not just
log/lin. The only camera we've never characterized is RED, so we'd
have to leave that to someone else. (Or could adapt the nuke one for
use in our environment).

For device profiles the only ones we ever use are srgb, r709, and p3
dlp. These will be included.


thanks

Bruno NIcoletti


[ocs-dev] Foundry Questions

brunobignose <bruno.j....@...>
 

Hi All,

this is a collection of questions that we came up with at The Foundry
after sitting down with various product manager and techy types....

What is you internal representation?
- we know you want to present this as a black box but we would like
to know some technical details
- what are the scope of the manipulations, are they all 3D ? Mixed 1D
and 3D?
- how do you represent
- transforms
- display devices
- looks

What third party LUTs do you manage?
- any open source ones?
- what happens if a user doesn't have a license for a proprietary lut
library?

How does one go about generating...
- LUTs?
- display profiles?
- looks?
- anything else in there...

Are you looking at making it extensible?

How does this all play with ICC proiles?

What level of thread safety is there?

Invertibility,
- how guaranteed is that for the general colour transforms?
- can you flag invertible transforms in any way?

Distributing colour management XML and LUTS
- have you thought of how to pack XML + LUTS + whatever into a single
file for distribution?
- zip/tgz/voodoo?

OpenGL fragment shaders
- how do we/you manage any LUTs that need to go along with the
shaders you create?
- have you thought about OpenCL code generation?
- we want to be able to supply our own names for objects in generated
code so as to avoid name collision, eg: the function name,

On going support
- who is responsible for support?
- how do we manage folding in fixes?

Are you shipping it with any vanilla XFMs that you have created at
Sony?
- and not just log/lin
- device profiles?

thanks

Bruno NIcoletti


New header, 0.5.1, now posted

Jeremy Selan <jeremy...@...>
 

Addresses Larry + Rods comments (mostly).

Coming soon, a mutable ColorConfig + better GLSL version-ness.
(And after that, a library that builds)


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Re: New header, 0.5.0, now posted

Jeremy Selan <jeremy...@...>
 

On Apr 22, 11:31 am, Larry Gritz <l....@imageworks.com> wrote:
Random questions:

What is the role of the 'direction' parameter to
ApplyColorSpaceTransform? Why would the user not just reverse the
InputColorSpace and OutputColorSpace parameter ordering to get the
reverse transformation?
Yah, the simple version is what we've had for 6 years. I added the
direction parameter for completeness yesterday. On second thought,
I'll drop it. ;)


Any reason why 'long' rather than 'int' in so many places? (I'm not
necessarily objecting, just curious.)
I'm just super used to working in CPython land so often they look
natural to me. (Python's native 'Int' data type is long - so using
them all over makes writing python glue a tiny bit more braindead).
But this is not a great reason to use longs, i'll roll it back.
http://docs.python.org/release/2.5/api/intObjects.html#l2h-384

Any role for OpenCL in addition to GLSL and Cg?
Sure, if anyone ever needs it it would make good sense. Does OpenCL
support accelerated 3d texture lookups? If so, it'll map well.
Otherwise, a bit more complex but still do-able. Probably not for 1.0
though...

Do you think "FilmLook" might seem anachronistic in the future or hurt
adoption in non-film pipelines? DisplayLook? OutputLook?
Yah, I agree FilmLook is not very forward-looking. I like your ideas,
I'll probably steal one of em.


Is it long/redundant to have ApplyASCColorCorrectionTransform,
ApplyFilmlookTransform, etc? If they were all called ApplyTransform,
they could still be distinguished by the argument types
(ASCColorCorrection& vs FilmLook&, etc.). A matter of style, not
critical, just bringing it up in case others prefer to avoid names
that are extra long only because they have redundancy in the naming
and arguments.
Yes, these names are redundant. I'll shorten them up. I think part
of the reason I went for a long name is that I've been looking at the
code for so long (at least a prior version) that I'm a bit dead to
it. Fresh eyes on an API help quite a bit.


stride_t -- you never define. Either change to ptrdiff_t, or typedef
them and use stride_t everywhere.
Fixed.

ImageView will surely need pixel accessor methods.
Not externally, is my hope. Once the user constructs an ImageView,
other than passing it in I dont want them to call anything on it.
Internally, I can decorate the Imp with any private accessors I'd like
to use.

What does ColorSpace::isData() do?
Colorspaces that are 'data' are a bit special. Basically, any
colorspace transforms you try to apply to them are ignored. (Think of
applying a ColorCorrection to an ID pass). Also, in the Filmlook pass
it obeys special 'data min' and 'data max' args. I will document it
as such.

Thanks for all the comments! They are hugely appreciated.


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Re: New header, 0.5.0, now posted

Jeremy Selan <jeremy...@...>
 

ApplyColorSpaceTransform does not use the roles.

GetHWFilmlook does. For example, if the fStopExposure arg is
specified, the exposure is adjusted internally in the SCENE_LINEAR
space (as specified by the role). If an ASCColorCorrection is
specified, this occurs in ROLE_COLOR_TIMING colorspace.

Additionally, plugins often rely on them. In our current Nuke
plugin, we have a LogConvert node that essentially does
ApplyColorSpaceTransform between ROLE_SCENE_LINEAR and
ROLE_COMPOSITING_LOG. This is convenient as end-user compositors
often know they want a 'Log Convert', but dont really want to concern
themselves with the specifics for which conversions to use.

I will update the header docs to make the functions which rely on
roles more obvious.

Would you agree with this concept? Assigning 'roles' at a high level
really is useful for a facility, but it's a slippery slope for sure in
having too many of them, and/or making them too facility specific.

The alternative would be to expose the roles as additional arguments.
(For example, in the HW filmlook exposure call an arg would be to
explicitly pass in the fstop exposure colorspace).

-- Jeremy

On Apr 22, 11:03 am, Rod Bogart <bog...@gmail.com> wrote:
Is the ColorSpace "role" just a database sorting tag, or does the
"role" impact the internal process of conversion?

RGB


Re: New header, 0.5.0, now posted

Larry Gritz <l...@...>
 

Random questions:

What is the role of the 'direction' parameter to
ApplyColorSpaceTransform? Why would the user not just reverse the
InputColorSpace and OutputColorSpace parameter ordering to get the
reverse transformation?

Any reason why 'long' rather than 'int' in so many places? (I'm not
necessarily objecting, just curious.)

Any role for OpenCL in addition to GLSL and Cg?

Do you think "FilmLook" might seem anachronistic in the future or hurt
adoption in non-film pipelines? DisplayLook? OutputLook?

Is it long/redundant to have ApplyASCColorCorrectionTransform,
ApplyFilmlookTransform, etc? If they were all called ApplyTransform,
they could still be distinguished by the argument types
(ASCColorCorrection& vs FilmLook&, etc.). A matter of style, not
critical, just bringing it up in case others prefer to avoid names
that are extra long only because they have redundancy in the naming
and arguments.

stride_t -- you never define. Either change to ptrdiff_t, or typedef
them and use stride_t everywhere.

ImageView will surely need pixel accessor methods.

What does ColorSpace::isData() do?



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