I'm emailing support about this, maybe they can shed some light on the
difference between Linear and Linear Half Float.
Thanks all for the help!
Ron Ganbar
email: ron...@gmail.com
tel: +44 (0)7968 007 309 [UK]
+972 (0)54 255 9765 [Israel]
url: http://ronganbar.wordpress.com/
On 21 December 2011 12:41, Fredrik Pihl <fre...@gmail.com> wrote:
> Well, not pushed perhaps, but "mapped" so that a correct exposure
> (depending of chosen ISO) of a gray chart will end up somewhere around 0.18.
>
> A klipping from a conversation I had with Graeme Natress at red shows:
>
> "With linear EXR output, we aim to put mid grey at 0.18 in the EXR file
> as requested by it's inventors at ILM. If you think about it, that gives
> only 2.5 stops or so between 0.18 and 1.0, and in ISO800 where we have
> about 5 stops above mid grey, that's going to generate values in the 0 to
> ~5.7 range. Higher ISOs will produce higher output values, always keeping
> mid grey at 0.18."
>
>
> //fredrik
>
>
>
> On Wed, Dec 21, 2011 at 8:38 AM, Randy Little <randyslit...@gmail.com>wrote:
>
>> 18% grey isn't pushed to .18 .18=18% of 0-1 linear response.
>> 18%grey is what happens if you mix 50%black and 50%white and spin it
>> really fast. You get a scene average reflectance of 18%. The chips
>> aren't reordering more then 16bits INT. the only reason you need/want
>> float is when you start playing with Curves you start remaping the
>> data and in this way you aren't going to lose anything. For Ron's
>> issue my guess is that what he is getting is INT sRGB with the values
>> remapped and in nuke you are getting linear without any remapping of
>> values to fit under 1.0. THUS blacks aren't getting crushed in nuke
>> like they are in redcine. ALL of these is pretty easy to solve with
>> a macbeth cart or a greyscale wedge.
>>
>> Randy S. Little
>> http://www.rslittle.com
>>
>>
>>
>>
>> On Tue, Dec 20, 2011 at 23:20, Simon Björk <si...@stillerstudios.se>
>> wrote:
>> > The term half float linear is a bit of a strange name for a gamma curve
>> I
>> > must say, and it definitely causes a lot of confusion. In this case,
>> from
>> > what I understand, half float linear is a linear curve where 18% grey is
>> > mapped to 0.18. This explains why bright values are pushed above
>> > 1.0. However, I'm not full understanding what's happening. If that was
>> the
>> > only thing that's happening compared to (the old and don't use) linear
>> > option, I would think that you could match the two with a simple
>> multiply.
>> > But you can't. Saturation/contrast is still way different between the
>> two.
>> >
>> > Regarding RedCineX, in newer versions (last year or so) it allows you to
>> > export EXRs with values above 1.0. You don't have the half float linear
>> > option in there, but actually it doesn't matter what gamma setting you
>> > chose. If you render EXRs from RedCineX it will output linear EXRs with
>> 18%
>> > grey pushed to 0.18.
>> >
>> > In my opinion the half float linear option in Nuke should be renamed to
>> > something else. Or just replace the current linear option (which is
>> there
>> > for legacy reasons).
>> >
>> > /Simon
>> >
>> >
>> > 2011/12/20 Deke Kincaid <dekekinc...@gmail.com>
>> >>
>> >> Either way the r3d reader set to linear will clamp at 1.0, set to half
>> >> linear float will go beyond 1.0. I don't pretend to know what the red
>> sdk
>> >> is doing under the hood. Half linear float option does not exist under
>> >> redcinex.
>> >>
>> >> -deke
>> >>
>> >>
>> >> On Tue, Dec 20, 2011 at 13:45, Randy Little <randyslit...@gmail.com>
>> >> wrote:
>> >>>
>> >>> clamped to 1.0 or raw data mapped to values between 0-1.0 with 3
>> >>> places of precision. But I am pretty sure the d/a in every camera is
>> >>> integer and mapping data into integer space for its raw file.
>> >>> http://www.rslittle.com
>> >>>
>> >>>
>> >>>
>> >>>
>> >>> On Tue, Dec 20, 2011 at 13:37, Howard Jones <mrhowardjo...@yahoo.com>
>> >>> wrote:
>> >>> > 1.0 is half float/float even if not clamped ;)
>> >>> > for Ron's question (if I read it right)
>> >>> >
>> >>> > Half float or 16 bit float is a less accurate version of 32 bit
>> float.
>> >>> > AFAIK The float being the floating point part of the number. you
>> dont
>> >>> > save
>> >>> > 123.45678 you save 12345678 with a bit(?) for the position of the
>> >>> > floating
>> >>> > point.
>> >>> > The difference between 16bit (half float) and 32 bit (float) is that
>> >>> > with
>> >>> > 16bit the length of that number gets truncated at a lesser degree of
>> >>> > accuracy compared to 32bit.
>> >>> > You could have 10 or 8bit float if you wanted, just not much point
>> for
>> >>> > what
>> >>> > we do. Similarly you could have 32bit non-float if you really
>> wanted,
>> >>> > but
>> >>> > again no point in our game afaic - as far as I care ;)
>> >>> >
>> >>> > Linear is linear, but again you could put any gamma or other curve
>> in
>> >>> > there
>> >>> > if you wanted.
>> >>> >
>> >>> > http://en.wikipedia.org/wiki/Half-precision_floating-point_format
>> >>> >
>> >>> > Howard
>> >>> >
>> >>> > ________________________________
>> >>> > From: "randyslit...@gmail.com" <randyslit...@gmail.com>
>> >>> >
>> >>> > To: Nuke user discussion <nuke-users@support.thefoundry.co.uk>
>> >>> > Sent: Tuesday, 20 December 2011, 20:24
>> >>> > Subject: Re: [Nuke-users] Redcine-X VS Nuke
>> >>> >
>> >>> > 1.0 is half float if it encoded half float and clamp to 1.0
>> >>> >
>> >>> > Sent from myTouch 4G
>> >>> >
>> >>> > ----- Reply message -----
>> >>> > From: "Deke Kincaid" <dekekinc...@gmail.com>
>> >>> > To: "Nuke user discussion" <nuke-users@support.thefoundry.co.uk>
>> >>> > Subject: [Nuke-users] Redcine-X VS Nuke
>> >>> > Date: Tue, Dec 20, 2011 12:13
>> >>> >
>> >>> >
>> >>> > Last I knew RedcineX only outputs EXR to "linear" which caps out at
>> >>> > 1.0, not
>> >>> > half linear float.
>> >>> >
>> >>> > -deke
>> >>> >
>> >>> > On Tue, Dec 20, 2011 at 04:29, Simon Björk <si...@stillerstudios.se
>> >
>> >>> > wrote:
>> >>> >
>> >>> > I might be misunderstanding you, but why the srgb2lin conversion?
>> >>> > RedcineX
>> >>> > only outputs linear exrs so as far as I know you shouldn't use any
>> >>> > colorspace convertions in Nuke if you chose that path. You can test
>> >>> > this if
>> >>> > you try different gamma curves in RedcineX and render to EXR. They
>> >>> > should
>> >>> > all look identical.
>> >>> >
>> >>> > Regarding my earlier post about half float linear gamma setting in
>> Nuke
>> >>> > should match a rendered exr from RedcineX, I just tested this and it
>> >>> > doesn't
>> >>> > seem to work. I'm pretty sure this worked earlier, but I might be
>> >>> > wrong. The
>> >>> > "linear gamma curve" in Nukes R3D importer is an old one and
>> shouldn't
>> >>> > be
>> >>> > used. Not sure why it's still there.
>> >>> >
>> >>> > This whole R3D in other applications often causes problems. Same in
>> >>> > After
>> >>> > Effects. I find that the most reliable solution (still unreliable)
>> is
>> >>> > to
>> >>> > output from RedcineX.
>> >>> >
>> >>> > /Simon
>> >>> >
>> >>> >
>> >>> >
>> >>> > 2011/12/20 Deke Kincaid <dekekinc...@gmail.com>
>> >>> >
>> >>> > I forgot to mention that It all depends what file format your
>> >>> > outputting. If
>> >>> > your outputting to dpx or tiff then set the decode colorspace/gamma
>> >>> > curve
>> >>> > the same as RedcineX but in the write node set the colorspace to
>> >>> > "linear".
>> >>> > While working with the R3d though, the viewer will look different
>> from
>> >>> > RedcineX unless you set it to linear. After reading back in the
>> >>> > dpx/tiff,
>> >>> > then you can set the viewer back to srgb and it will look correct.
>> >>> >
>> >>> > If your outputting to Exr from RedcineX then you need add a
>> colorspace
>> >>> > node
>> >>> > with in:sRGB and out:Linear (Read node settings all should match
>> >>> > RedcineX).
>> >>> > While this is technically incorrect but it will give you the
>> >>> > equivalent of
>> >>> > burning the grade into the EXR.
>> >>> >
>> >>> > People here are mentioning using Half Linear Float which does
>> properly
>> >>> > linearize the curve form the chip when going to EXR. You would
>> need to
>> >>> > extract a lut between the linear R3d and your director's color to
>> use
>> >>> > as a
>> >>> > viewer lut and use that in the write node.
>> >>> >
>> >>> > -deke
>> >>> >
>> >>> >
>> >>> > On Tue, Dec 20, 2011 at 00:15, Ron Ganbar <ron...@gmail.com> wrote:
>> >>> >
>> >>> > Thanks for this Deke.
>> >>> > The settings are all the same, but looking at the Nuke Viewer set to
>> >>> > sRGB, I
>> >>> > see a very washed out image - what I would normally consider a
>> Cineon
>> >>> > looking image. Looking at the Redcine-X viewer it looks correct.
>> >>> > Any ideas?
>> >>> >
>> >>> >
>> >>> > Ron Ganbar
>> >>> > email: ron...@gmail.com
>> >>> > tel: +44 (0)7968 007 309 [UK]
>> >>> > +972 (0)54 255 9765 [Israel]
>> >>> > url: http://ronganbar.wordpress.com/
>> >>> >
>> >>> >
>> >>> >
>> >>> > On 20 December 2011 09:48, Deke Kincaid <dekekinc...@gmail.com>
>> wrote:
>> >>> >
>> >>> > First, try hitting the "Metadata" button in the read node. That
>> should
>> >>> > make
>> >>> > it grab the right color settings. If not you can match the same
>> >>> > settings in
>> >>> > Nuke as the one he has in RedcineX (they should all be named the
>> same).
>> >>> >
>> >>> > Also make sure your using Nuke 6.3v5 because it includes RedGamma2
>> and
>> >>> > RedColor2 which is missing from versions before that (older SDK).
>> >>> >
>> >>> > -deke
>> >>> >
>> >>> > On Mon, Dec 19, 2011 at 23:34, Ron Ganbar <ron...@gmail.com> wrote:
>> >>> >
>> >>> > Hi all,
>> >>> > I don't have a lot of experience with converting R3D files, but I so
>> >>> > far did
>> >>> > it with Nuke and was pretty happy with the result.
>> >>> > However, a director, who is technically minded, just told me that
>> when
>> >>> > he
>> >>> > takes something into Redcine-X and without changing the color at
>> all he
>> >>> > gets
>> >>> > something he likes. I did the same thing, and indeed the image looks
>> >>> > nice.
>> >>> > When I do the same thing in Nuke I get a very washed image. What's
>> the
>> >>> > output colorspace of the Nuke R3D read node? How can I get the same
>> >>> > kind of
>> >>> > output from Nuke's Read node to Redcine-X's output?
>> >>> >
>> >>> > Thanks,
>> >>> > Ron Ganbar
>> >>> > email: ron...@gmail.com
>> >>> > tel: +44 (0)7968 007 309 [UK]
>> >>> > +972 (0)54 255 9765 [Israel]
>> >>> > url: http://ronganbar.wordpress.com/
>> >>> >
>> >>> >
>> >>> > _______________________________________________
>> >>> > Nuke-users mailing list
>> >>> > Nuke-users@support.thefoundry.co.uk,
>> http://forums.thefoundry.co.uk/
>> >>> > http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users
>> >>> >
>> >>> >
>> >>> >
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>> >>> >
>> >>> >
>> >>> >
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>> >>> >
>> >>> >
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>> >>> >
>> >>> >
>> >>> >
>> >>> >
>> >>> > --
>> >>> > --------------------------------
>> >>> > Stiller Studios
>> >>> > Lidingö/Sweden
>> >>> >
>> >>> > Simon Björk
>> >>> > Stiller Studios
>> >>> > +46 (0)8 555 23 560
>> >>> > Ekholmsnäsvägen 40, S-181 41 Lidingö
>> >>> > si...@stillerstudios.se
>> >>> > www.stillerstudios.se
>> >>> >
>> >>> > find us:
>> >>> >
>> >>> >
>> http://www.eniro.se/query?search_word=stiller+studios&geo_area=liding%F6&what=all
>> >>> >
>> >>> >
>> >>> >
>> >>> > _______________________________________________
>> >>> > Nuke-users mailing list
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>> http://forums.thefoundry.co.uk/
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>> >>> >
>> >>> >
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>> >>> >
>> >>> >
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>> >>
>> >>
>> >> _______________________________________________
>> >> Nuke-users mailing list
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>> >
>> >
>> >
>> >
>> > --
>> > --------------------------------
>> > Stiller Studios
>> > Lidingö/Sweden
>> >
>> > Simon Björk
>> > Stiller Studios
>> > +46 (0)8 555 23 560
>> > Ekholmsnäsvägen 40, S-181 41 Lidingö
>> > si...@stillerstudios.se
>> > www.stillerstudios.se
>> >
>> > find us:
>> >
>> http://www.eniro.se/query?search_word=stiller+studios&geo_area=liding%F6&what=all
>> >
>> >
>> >
>> > _______________________________________________
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>
>
>
> --
> ______________________________
> Fredrik Pihl
> visual effects supervisor - digital compositor
> +46-708-559 559
>
> _______________________________________________
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