lcms-user — For users of the little cms library

Re: [Lcms-user] Create generic CMYK profile

[Marco F. <Mar...@en...>]

Hi Christian,

Why don't you use a "standard" CMYK profile as default, that is likely to be correct or "close"?

Depending on where you are (I assume Germany based on name and email) and what your purpose is, for example FOGRA27 or FOGRA39 might be good defaults. Or SWOPV2 (typically for US). If this is an end-user App, be phony to the user about that usage of a default profile or make it configurable...

Marco

-----Original Message-----
From: Christian Schmitz [mailto:rea...@mo...] 
Sent: Dienstag, 21. Juni 2016 13:44
To: lcm...@li...
Subject: [Lcms-user] Create generic CMYK profile

Hi,

sometimes I have to render CMYK and need a profile.

Instead of using an ICC file, can I just create a simply ICC profile for CMYK?

One which can be used to render to RGB and give a preview?

Sincerely
Christian

--
Read our blog about news on our plugins:

http://www.mbsplugins.de/


------------------------------------------------------------------------------
Attend Shape: An AT&T Tech Expo July 15-16. Meet us at AT&T Park in San Francisco, CA to explore cutting-edge tech and listen to tech luminaries present their vision of the future. This family event has something for everyone, including kids. Get more information and register today.
http://sdm.link/attshape
_______________________________________________
Lcms-user mailing list
Lcm...@li...
https://lists.sourceforge.net/lists/listinfo/lcms-user

[Lcms-user] Create generic CMYK profile

[Christian S. <rea...@mo...>]

Hi,

sometimes I have to render CMYK and need a profile.

Instead of using an ICC file, can I just create a simply ICC profile for CMYK?

One which can be used to render to RGB and give a preview?

Sincerely
Christian

-- 
Read our blog about news on our plugins:

http://www.mbsplugins.de/

Re: [Lcms-user] Softproofing with parametric tonecurve

[Marti M. <mar...@li...>]

Hi Tobias, could you explain a little bit more how you use this profile with softproofing? What result do you expect? What are you getting? This would help to catch the bug if this is the case

Thanks
Marti

On Jun 20, 2016 12:19 PM, Tobias Ellinghaus <me...@ho...> wrote:
>
> Hello, 
>
> I am currently struggling to use a profile with a parametric tone curve for 
> softproofing. Is there a know limitation regarding that? When I use a straight 
> gamma it works. Alternatively I can dump the profile to disk or memory and read 
> it again to get something working. 
>
> The code to create the profile is here: 
>
> https://github.com/darktable-org/darktable/blob/master/src/common/colorspaces.c#L286-L297 
>
> and 
>
> https://github.com/darktable-org/darktable/blob/master/src/common/colorspaces.c#L238-L284 
>
> I would appreciate any hints about what is happening. 
>
> Thanks 
> Tobias
> ------------------------------------------------------------------------------ 
> What NetFlow Analyzer can do for you? Monitors network bandwidth and traffic 
> patterns at an interface-level. Reveals which users, apps, and protocols are 
> consuming the most bandwidth. Provides multi-vendor support for NetFlow, 
> J-Flow, sFlow and other flows. Make informed decisions using capacity planning 
> reports. http://sdm.link/zohomanageengine

Re: [Lcms-user] Softproofing with parametric tonecurve

[Kai-Uwe B. <ku...@gm...>]

Am 20.06.2016 um 12:19 schrieb Tobias Ellinghaus:
> I am currently struggling to use a profile with a parametric tone 
> curve for softproofing. Is there a know limitation regarding that? 
> When I use a straight gamma it works. Alternatively I can dump the 
> profile to disk or memory and read it again to get something 
> working.

Could you compare with the cmsCreate_sRGBProfile() API?

[Lcms-user] Softproofing with parametric tonecurve

[Tobias E. <me...@ho...>]

Hello,

I am currently struggling to use a profile with a parametric tone curve for 
softproofing. Is there a know limitation regarding that? When I use a straight 
gamma it works. Alternatively I can dump the profile to disk or memory and read 
it again to get something working.

The code to create the profile is here:

https://github.com/darktable-org/darktable/blob/master/src/common/colorspaces.c#L286-L297

and

https://github.com/darktable-org/darktable/blob/master/src/common/colorspaces.c#L238-L284

I would appreciate any hints about what is happening.

Thanks
Tobias

Re: [Lcms-user] lcms2-2.8 release candidate 1 available for testing

[Noel C. <NCa...@Pr...>]

On Mon, 6 Jun 2016, Marti Maria wrote:

> After some time of inactivity I?ve taken again the development of
> lcms, so here is the first release candidate for lcms
> 2.8

We have put the 2.8 beta library through quite a bit of testing over the
past weeks and have uncovered no problems.  We even ran a number of runs
with the Microsoft Application Verifier with all the checks turned on
and never had a bit of trouble.  No leaks, no buffer overflows.  We did
a LOT of multi-threaded transform operations.

Little CMS is proving to be very robust.  Thank you!

-Noel

Re: [Lcms-user] Difficulty with cmsTransform in C#

[Marti M. <mar...@li...>]

Hi Roger,

I'm not a c# expert, but your code seems fine. I guess the problem is
elsewhere...

Regards
Marti Maria
The LittleCMS project
http://www.littlecms.com 

-----Original Message-----
From: Roger Breton [mailto:gr...@vi...] 
Sent: jueves, 16 de junio de 2016 21:25
To: lcm...@li...
Subject: [Lcms-user] Difficulty with cmsTransform in C#

Tengo una pequena problema...

I need to convert 400 RGB values to Lab using a monitor profile.

I use the following C# code :

  string Source = "Monitor.icm";
  IntPtr hSource = cmsOpenProfileFromFile(Source, "r");

  xform = cmsCreateTransform(hSource, TYPE_RGB_DBL, hLab2, TYPE_Lab_DBL,
INTENT_ABSOLUTE_COLORIMETRIC, 0);

  for (int i = 0; i < 400; i++)
  {
          input[0] = R[i];
          input[1] = G[i];
          input[2] = B[i];

           cmsDoTransform(xform, input, output, 1);

           L = output[0];
           a = output[1];
           b = output[2];
}

First time through the loop I get valid Lab results.
But subsequent passage through the loop always return the same Lab values?
The input[] values do change as expected.

When I use this code outside of a loop, it works perfect.

/ Roger Breton


----------------------------------------------------------------------------
--
What NetFlow Analyzer can do for you? Monitors network bandwidth and traffic
patterns at an interface-level. Reveals which users, apps, and protocols are
consuming the most bandwidth. Provides multi-vendor support for NetFlow,
J-Flow, sFlow and other flows. Make informed decisions using capacity
planning reports. http://sdm.link/zohomanageengine
_______________________________________________
Lcms-user mailing list
Lcm...@li...
https://lists.sourceforge.net/lists/listinfo/lcms-user

Re: [Lcms-user] Difficulty with cmsTransform in C#

[Edgar L. <lo...@co...>]

Did you declare input[] and output[] as volatile?
(s. https://msdn.microsoft.com/de-de/library/x13ttww7.aspx)

Edgar


Am 16.06.2016 um 21:25 schrieb Roger Breton:
> Tengo una pequena problema...
>
> I need to convert 400 RGB values to Lab using a monitor profile.
>
> I use the following C# code :
>
>   string Source = "Monitor.icm";
>   IntPtr hSource = cmsOpenProfileFromFile(Source, "r");
>
>   xform = cmsCreateTransform(hSource, TYPE_RGB_DBL, hLab2, TYPE_Lab_DBL,
> INTENT_ABSOLUTE_COLORIMETRIC, 0);
>
>   for (int i = 0; i < 400; i++)
>   {
>           input[0] = R[i];
>           input[1] = G[i];
>           input[2] = B[i];
>
>            cmsDoTransform(xform, input, output, 1);
>
>            L = output[0];
>            a = output[1];
>            b = output[2];
> }
>
> First time through the loop I get valid Lab results.
> But subsequent passage through the loop always return the same Lab values?
> The input[] values do change as expected.
>
> When I use this code outside of a loop, it works perfect.
>
> / Roger Breton
>
>
> ------------------------------------------------------------------------------
> What NetFlow Analyzer can do for you? Monitors network bandwidth and traffic
> patterns at an interface-level. Reveals which users, apps, and protocols are
> consuming the most bandwidth. Provides multi-vendor support for NetFlow,
> J-Flow, sFlow and other flows. Make informed decisions using capacity planning
> reports. http://sdm.link/zohomanageengine
> _______________________________________________
> Lcms-user mailing list
> Lcm...@li...
> https://lists.sourceforge.net/lists/listinfo/lcms-user
>

-- 
lakeBits Inh. Edgar Loser
Haydnstr. 25
78464 Konstanz
Tel 0049 7531 5844154 0
Fax 0049 7531 5844154 9
http://www.colymp.com/
mailto:lo...@co...

[Lcms-user] Difficulty with cmsTransform in C#

[Roger B. <gr...@vi...>]

Tengo una pequena problema...

I need to convert 400 RGB values to Lab using a monitor profile.

I use the following C# code :

  string Source = "Monitor.icm";
  IntPtr hSource = cmsOpenProfileFromFile(Source, "r");

  xform = cmsCreateTransform(hSource, TYPE_RGB_DBL, hLab2, TYPE_Lab_DBL,
INTENT_ABSOLUTE_COLORIMETRIC, 0);

  for (int i = 0; i < 400; i++)
  {
          input[0] = R[i];
          input[1] = G[i];
          input[2] = B[i];

           cmsDoTransform(xform, input, output, 1);

           L = output[0];
           a = output[1];
           b = output[2];
}

First time through the loop I get valid Lab results.
But subsequent passage through the loop always return the same Lab values?
The input[] values do change as expected.

When I use this code outside of a loop, it works perfect.

/ Roger Breton

Re: [Lcms-user] lcms2-2.8 release candidate 1 available for testing

[Marti M. <mar...@li...>]

 

Hi,

 

Looks great!

 

I have added your changes to the git repository. Many thanks for your
contribution.

 

Best regards,

Marti Maria

The LittleCMS project

http://www.littlecms.com 

 

From: Noel Carboni [mailto:NCa...@Pr...] 
Sent: martes, 7 de junio de 2016 21:34
To: 'Marti Maria' <mar...@li...>;
lcm...@li...
Subject: RE: [Lcms-user] lcms2-2.8 release candidate 1 available for testing

 

Hi Marti,

 

More info related to the cmsFLAGS_COPY_ALPHA flag...

 

Please allow me to make some suggestions to improve the speed of in-place
color conversions (i.e., conversions of colors in a single image, where no
copy is occurring from one buffer to another):

 

 

1.  Add these statements to the _cmsHandleExtraChannels() function:

 

               // Exit early if in-place color-management is occurring - no
need to copy extra channels to themselves.

               if (p->InputFormat == p->OutputFormat && in == out)

                              return;

 

I've tested the above and it does make a difference in speed for the
common/typical operation of in-place color-management.

 

 

2.  I've also tested hand-optimizing copying the extra info for one extra
channel each for input/output - another very typical scenario - and by
reducing the array variables to simple variables the entire innermost loop
can be run only from registers.  It does make a difference in the speed when
one extra channel is copied (e.g., for RGBA).  That actually brought the
LittleCMS time to do the task on 8 bit to 8 bit transforms in line with the
optimized code we had already written.

 

Here is a copy of the optimized c file.  It's all yours to include in the
package if you'd like to use it.  All of the changes are in the
_cmsHandleExtraChannels() function.

 

http://Noel.ProDigitalSoftware.com/temp/cmsalpha.c

 

Using Visual Studio 2015, the assembly instructions for the innermost
per-pixel loop for the optimized "one extra field" function are reduced by
the optimizer to this quite efficient set:

 

$LL7@cmsHandleE:

 

; 466  :                                                copyValueFn(DestPtr,
SourcePtr);

 

            mov    rdx, rbx

            mov    rcx, rdi

            call      r15

 

; 468  :                                                SourcePtr +=
SourceIncrements[0];

 

            add      rbx, r14

 

; 469  :                                                DestPtr   +=
DestIncrements[0];

 

            add      rdi, r12

            sub      rsi, 1

            jne       SHORT $LL7@cmsHandleE

 

-Noel

 

From: Marti Maria [mailto:mar...@li...] 
Sent: Mon, June 6, 2016 3:36 PM
To: lcm...@li... <mailto:lcm...@li...>

Subject: [Lcms-user] lcms2-2.8 release candidate 1 available for testing

 

 

Hi,

 

After some time of inactivity I've taken again the development of lcms, so
here is the first release candidate for lcms 2.8

 

Most of code is sponsored by Alien Skin Software, thank you so much for this
great contribution!

 

Aside of bugfixes, 2.8 does support alpha channel transportation and a new
transform stride function and plug-in which can be used to increase
significantly the processing speed.

 

See here the release candidate http://www.littlecms.com/lcms2-2.8rc1.tar.gz

 

Best regards

 

Marti Maria

The LittleCMS project

http://www.littlecms.com 

 

Re: [Lcms-user] lcms2-2.8 release candidate 1 available for testing

[Noel C. <NCa...@Pr...>]

Hi Marti,

 

More info related to the cmsFLAGS_COPY_ALPHA flag...

 

Please allow me to make some suggestions to improve the speed of
in-place color conversions (i.e., conversions of colors in a single
image, where no copy is occurring from one buffer to another):

 

 

1.  Add these statements to the _cmsHandleExtraChannels() function:

 

               // Exit early if in-place color-management is occurring -
no need to copy extra channels to themselves.

               if (p->InputFormat == p->OutputFormat && in == out)

                              return;

 

I've tested the above and it does make a difference in speed for the
common/typical operation of in-place color-management.

 

 

2.  I've also tested hand-optimizing copying the extra info for one
extra channel each for input/output - another very typical scenario -
and by reducing the array variables to simple variables the entire
innermost loop can be run only from registers.  It does make a
difference in the speed when one extra channel is copied (e.g., for
RGBA).  That actually brought the LittleCMS time to do the task on 8 bit
to 8 bit transforms in line with the optimized code we had already
written.

 

Here is a copy of the optimized c file.  It's all yours to include in
the package if you'd like to use it.  All of the changes are in the
_cmsHandleExtraChannels() function.

 

http://Noel.ProDigitalSoftware.com/temp/cmsalpha.c

 

Using Visual Studio 2015, the assembly instructions for the innermost
per-pixel loop for the optimized "one extra field" function are reduced
by the optimizer to this quite efficient set:

 

$LL7@cmsHandleE:

 

; 466  :
copyValueFn(DestPtr, SourcePtr);

 

            mov    rdx, rbx

            mov    rcx, rdi

            call      r15

 

; 468  :                                                SourcePtr +=
SourceIncrements[0];

 

            add      rbx, r14

 

; 469  :                                                DestPtr   +=
DestIncrements[0];

 

            add      rdi, r12

            sub      rsi, 1

            jne       SHORT $LL7@cmsHandleE

 

-Noel

 

From: Marti Maria [mailto:mar...@li...] 
Sent: Mon, June 6, 2016 3:36 PM
To: lcm...@li...
Subject: [Lcms-user] lcms2-2.8 release candidate 1 available for testing

 

 

Hi,

 

After some time of inactivity I've taken again the development of lcms,
so here is the first release candidate for lcms 2.8

 

Most of code is sponsored by Alien Skin Software, thank you so much for
this great contribution!

 

Aside of bugfixes, 2.8 does support alpha channel transportation and a
new transform stride function and plug-in which can be used to increase
significantly the processing speed.

 

See here the release candidate
http://www.littlecms.com/lcms2-2.8rc1.tar.gz

 

Best regards

 

Marti Maria

The LittleCMS project

http://www.littlecms.com 

 

Re: [Lcms-user] CMYK to CieLab

[Marti M. <mar...@li...>]

Hi,

>echo 10 90 0 10 | icctrans  -i"CoatedFOGRA39.icc" -o*Lab -n
>
>LittleCMS ColorSpace conversion calculator - v3.3
>
>47.4525 63.8438 -7.7734

This is exactly what PhotoShop CC 2015 gives


>echo 0 100 0 0 | icctrans  -i"CoatedFOGRA39.icc" -o*sRGB -n
>
>LittleCMS ColorSpace conversion calculator - v3.3
>
>229.56 0.00 125.60

Again, exact match after proper rounding.  I don't see what is wrong in
those calculations. 

>This is all VERY different to all other calculations I have seem for
example I would think RGB would be closer to 255 0 255

Please remember this is precision color management, so if you compare with
online converters that are applying  CMYK=1-RGB or things like that, results
are obviously different. But it is not Adobe or Littlecms who is wrong. RGB
255, 0, 255 is on gamut boundary which effectively is out of gamut. I doubt
any decent CMM will give 255, 0, 255, this is not in the ICC profile. 

Regards
Marti Maria
The LittleCMS project
http://www.littlecms.com 

-----Original Message-----
From: Harald Weinhandl [mailto:hv...@gm...] 
Sent: martes, 7 de junio de 2016 5:58
To: lcm...@li...
Subject: [Lcms-user] CMYK to CieLab

Hi

I have been trying all day to convert CMYK to Lab using the basic.

hTransform = cmsCreateTransform(
hCMYKProfile,
TYPE_CMYK_DBL,
 hLab,
TYPE_Lab_DBL,
INTENT_PERCEPTUAL,
0);


I have also tried icctrans which gives the same results

echo 10 90 0 10 | icctrans  -i"CoatedFOGRA39.icc" -o*Lab -n

LittleCMS ColorSpace conversion calculator - v3.3

47.4525 63.8438 -7.7734


If I also just use a simple CMYK to RGB

echo 0 100 0 0 | icctrans  -i"CoatedFOGRA39.icc" -o*sRGB -n

LittleCMS ColorSpace conversion calculator - v3.3

229.56 0.00 125.60

This is all VERY different to all other calculations I have seem for example
I would think RGB would be closer to
255 0 255

also checking many online converters

Am I doing something very wrong, I have tried other CMYK profiles like
USWebCoatedSWOP and they are nearly the same..

Harald

----------------------------------------------------------------------------
--
What NetFlow Analyzer can do for you? Monitors network bandwidth and traffic
patterns at an interface-level. Reveals which users, apps, and protocols are
consuming the most bandwidth. Provides multi-vendor support for NetFlow,
J-Flow, sFlow and other flows. Make informed decisions using capacity
planning reports. https://ad.doubleclick.net/ddm/clk/305295220;132659582;e
_______________________________________________
Lcms-user mailing list
Lcm...@li...
https://lists.sourceforge.net/lists/listinfo/lcms-user

Re: [Lcms-user] lcms2-2.8 release candidate 1 available for testing

[Boudewijn R. <bo...@va...>]

On Mon, 6 Jun 2016, Marti Maria wrote:

> 
> After some time of inactivity I’ve taken again the development of lcms, so here is the first release candidate for lcms
> 2.8
> 
> Most of code is sponsored by Alien Skin Software, thank you so much for this great contribution!
> 
> Aside of bugfixes, 2.8 does support alpha channel transportation and a new transform stride function and plug-in which
> can be used to increase significantly the processing speed.
> 
> See here the release candidate http://www.littlecms.com/lcms2-2.8rc1.tar.gz
>

Awesome news!

-- 
Boudewijn Rempt | http://www.krita.org, http://www.valdyas.org

[Lcms-user] CMYK to CieLab

[Harald W. <hv...@gm...>]

Hi

I have been trying all day to convert CMYK to Lab using the basic.

hTransform = cmsCreateTransform(
hCMYKProfile,
TYPE_CMYK_DBL,
 hLab,
TYPE_Lab_DBL,
INTENT_PERCEPTUAL,
0);


I have also tried icctrans which gives the same results

echo 10 90 0 10 | icctrans  -i"CoatedFOGRA39.icc" -o*Lab -n

LittleCMS ColorSpace conversion calculator - v3.3

47.4525 63.8438 -7.7734


If I also just use a simple CMYK to RGB

echo 0 100 0 0 | icctrans  -i"CoatedFOGRA39.icc" -o*sRGB -n

LittleCMS ColorSpace conversion calculator - v3.3

229.56 0.00 125.60

This is all VERY different to all other calculations I have seem for
example I would think
RGB would be closer to
255 0 255

also checking many online converters

Am I doing something very wrong, I have tried other CMYK profiles like
USWebCoatedSWOP and they are nearly the same..

Harald

Re: [Lcms-user] lcms2-2.8 release candidate 1 available for testing

[Noel C. <NCa...@Pr...>]

Thank you, Marti,

 

We're definitely going to be able to make use of the "copy alpha"
functionality.  It eats up a surprising amount of time to handle the
alpha separately.

 

-Noel

 

From: Marti Maria [mailto:mar...@li...] 
Sent: Mon, June 6, 2016 3:36 PM
To: lcm...@li...
Subject: [Lcms-user] lcms2-2.8 release candidate 1 available for testing

 

 

Hi,

 

After some time of inactivity I've taken again the development of lcms,
so here is the first release candidate for lcms 2.8

 

Most of code is sponsored by Alien Skin Software, thank you so much for
this great contribution!

 

Aside of bugfixes, 2.8 does support alpha channel transportation and a
new transform stride function and plug-in which can be used to increase
significantly the processing speed.

 

See here the release candidate
http://www.littlecms.com/lcms2-2.8rc1.tar.gz

 

Best regards

 

Marti Maria

The LittleCMS project

http://www.littlecms.com 

 

[Lcms-user] lcms2-2.8 release candidate 1 available for testing

[Marti M. <mar...@li...>]

 

Hi,

 

After some time of inactivity I've taken again the development of lcms, so
here is the first release candidate for lcms 2.8

 

Most of code is sponsored by Alien Skin Software, thank you so much for this
great contribution!

 

Aside of bugfixes, 2.8 does support alpha channel transportation and a new
transform stride function and plug-in which can be used to increase
significantly the processing speed.

 

See here the release candidate http://www.littlecms.com/lcms2-2.8rc1.tar.gz

 

Best regards

 

Marti Maria

The LittleCMS project

http://www.littlecms.com 

 

Re: [Lcms-user] How to create a gray profile with L-star grey response?

[Marco F. <Mar...@en...>]

OK, I'll give it a shot and try it. 

Thanks again, Elle, Marti, Florian for your answers!

Marco

-----Original Message-----
From: Marti Maria [mailto:mar...@li...] 
Sent: Dienstag, 24. Mai 2016 16:19
To: Marco Freudenberger; 'Florian Höch'; lcm...@li...
Subject: RE: [Lcms-user] How to create a gray profile with L-star grey response?

Hi,

Yes, that one. If you use cmsBuildGamma() you are forced to XYZ PCS, but if you use low-level you can use Lab PCS as well.

Regards
Marti Maria
The LittleCMS project
http://www.littlecms.com 


-----Original Message-----
From: Marco Freudenberger [mailto:Mar...@en...]
Sent: martes, 24 de mayo de 2016 16:14
To: Marti Maria <mar...@li...>; 'Florian Höch'
<lis...@ho...>; lcm...@li...
Subject: RE: [Lcms-user] How to create a gray profile with L-star grey response?

Marti,
 sorry, I'm not sure I understand your answer.

My intention is gray with L*, not Linear gray (Gamma 1.0), using the cmsBuildGamma would give me a gamma 1.0 response curve, though - at least when used with cmsCreateGrayProfile, right? Or am I missing something?

Are you suggesting I'm creating the profile "low level"? Something like:

cmsHPROFILE hProfile = cmsCreateProfilePlaceholder(ctx); cmsSetProfileVersion(hProfile, 4.3);
cmsSetDeviceClass(hProfile, cmsSigDisplayClass);	// or better
abstract?    
cmsSetColorSpace(hProfile, cmsSigGrayData);   
cmsSetPCS(hProfile, cmsSigLabData);
cmsSetHeaderRenderingIntent(hProfile, INTENT_RELATIVE_COLORIMETRIC); SetTextTags(hProfile, L"gray L-star") cmsCIEXYZ wpxyz; cmsxyY2XYZ(&wpxyz, WhitePoint); cmsWriteTag(hProfile, cmsSigMediaWhitePointTag, &wpxyz);
cmsToneCurve* tc = cmsBuildGamma(ctx, 1.0); // 1.0 gamma from Lab = L* ???????
cmsWriteTag(hProfile, cmsSigGrayTRCTag, (void*)tc)); cmsFreeToneCurve(tc);




-----Original Message-----
From: Marti Maria [mailto:mar...@li...]
Sent: Dienstag, 24. Mai 2016 15:50
To: Marco Freudenberger; 'Florian Höch'; lcm...@li...
Subject: RE: [Lcms-user] How to create a gray profile with L-star grey response?

Right, mark the PCS as Lab and use cmdBuildGamma(NULL, 1.0). You only need to add the white point and this curve.

Marti Maria
The LittleCMS project
http://www.littlecms.com 

-----Original Message-----
From: Florian Höch [mailto:lis...@ho...]
Sent: martes, 24 de mayo de 2016 15:19
To: lcm...@li...
Subject: Re: [Lcms-user] How to create a gray profile with L-star grey response?

Hi,

Am 24.05.2016 um 15:07 schrieb Marco Freudenberger:
> PS - to the group: I'm still wondering what would happen if I'd simply 
> set
the TransferFunction to NULL...

That would result in a gamma 1.0 response I think (according to the ICC spec).

Florian.

----------------------------------------------------------------------------
--
Mobile security can be enabling, not merely restricting. Employees who bring their own devices (BYOD) to work are irked by the imposition of MDM restrictions. Mobile Device Manager Plus allows you to control only the apps on BYO-devices by containerizing them, leaving personal data untouched!
https://ad.doubleclick.net/ddm/clk/304595813;131938128;j
_______________________________________________
Lcms-user mailing list
Lcm...@li...
https://lists.sourceforge.net/lists/listinfo/lcms-user

Re: [Lcms-user] How to create a gray profile with L-star grey response?

[Marti M. <mar...@li...>]

Hi,

Yes, that one. If you use cmsBuildGamma() you are forced to XYZ PCS, but if
you use low-level you can use Lab PCS as well.

Regards
Marti Maria
The LittleCMS project
http://www.littlecms.com 


-----Original Message-----
From: Marco Freudenberger [mailto:Mar...@en...] 
Sent: martes, 24 de mayo de 2016 16:14
To: Marti Maria <mar...@li...>; 'Florian Höch'
<lis...@ho...>; lcm...@li...
Subject: RE: [Lcms-user] How to create a gray profile with L-star grey
response?

Marti,
 sorry, I'm not sure I understand your answer.

My intention is gray with L*, not Linear gray (Gamma 1.0), using the
cmsBuildGamma would give me a gamma 1.0 response curve, though - at least
when used with cmsCreateGrayProfile, right? Or am I missing something?

Are you suggesting I'm creating the profile "low level"? Something like:

cmsHPROFILE hProfile = cmsCreateProfilePlaceholder(ctx);
cmsSetProfileVersion(hProfile, 4.3);
cmsSetDeviceClass(hProfile, cmsSigDisplayClass);	// or better
abstract?    
cmsSetColorSpace(hProfile, cmsSigGrayData);   
cmsSetPCS(hProfile, cmsSigLabData);
cmsSetHeaderRenderingIntent(hProfile, INTENT_RELATIVE_COLORIMETRIC);
SetTextTags(hProfile, L"gray L-star") cmsCIEXYZ wpxyz; cmsxyY2XYZ(&wpxyz,
WhitePoint); cmsWriteTag(hProfile, cmsSigMediaWhitePointTag, &wpxyz);
cmsToneCurve* tc = cmsBuildGamma(ctx, 1.0); // 1.0 gamma from Lab = L*
???????
cmsWriteTag(hProfile, cmsSigGrayTRCTag, (void*)tc)); cmsFreeToneCurve(tc);




-----Original Message-----
From: Marti Maria [mailto:mar...@li...]
Sent: Dienstag, 24. Mai 2016 15:50
To: Marco Freudenberger; 'Florian Höch'; lcm...@li...
Subject: RE: [Lcms-user] How to create a gray profile with L-star grey
response?

Right, mark the PCS as Lab and use cmdBuildGamma(NULL, 1.0). You only need
to add the white point and this curve.

Marti Maria
The LittleCMS project
http://www.littlecms.com 

-----Original Message-----
From: Florian Höch [mailto:lis...@ho...]
Sent: martes, 24 de mayo de 2016 15:19
To: lcm...@li...
Subject: Re: [Lcms-user] How to create a gray profile with L-star grey
response?

Hi,

Am 24.05.2016 um 15:07 schrieb Marco Freudenberger:
> PS - to the group: I'm still wondering what would happen if I'd simply 
> set
the TransferFunction to NULL...

That would result in a gamma 1.0 response I think (according to the ICC
spec).

Florian.

----------------------------------------------------------------------------
--
Mobile security can be enabling, not merely restricting. Employees who bring
their own devices (BYOD) to work are irked by the imposition of MDM
restrictions. Mobile Device Manager Plus allows you to control only the apps
on BYO-devices by containerizing them, leaving personal data untouched!
https://ad.doubleclick.net/ddm/clk/304595813;131938128;j
_______________________________________________
Lcms-user mailing list
Lcm...@li...
https://lists.sourceforge.net/lists/listinfo/lcms-user

Re: [Lcms-user] How to create a gray profile with L-star grey response?

[Marco F. <Mar...@en...>]

Marti,
 sorry, I'm not sure I understand your answer.

My intention is gray with L*, not Linear gray (Gamma 1.0), using the cmsBuildGamma would give me a gamma 1.0 response curve, though - at least when used with cmsCreateGrayProfile, right? Or am I missing something?

Are you suggesting I'm creating the profile "low level"? Something like:

cmsHPROFILE hProfile = cmsCreateProfilePlaceholder(ctx);
cmsSetProfileVersion(hProfile, 4.3);
cmsSetDeviceClass(hProfile, cmsSigDisplayClass);	// or better abstract?    
cmsSetColorSpace(hProfile, cmsSigGrayData);   
cmsSetPCS(hProfile, cmsSigLabData);
cmsSetHeaderRenderingIntent(hProfile, INTENT_RELATIVE_COLORIMETRIC);
SetTextTags(hProfile, L"gray L-star")
cmsCIEXYZ wpxyz;
cmsxyY2XYZ(&wpxyz, WhitePoint);
cmsWriteTag(hProfile, cmsSigMediaWhitePointTag, &wpxyz);
cmsToneCurve* tc = cmsBuildGamma(ctx, 1.0); // 1.0 gamma from Lab = L* ???????
cmsWriteTag(hProfile, cmsSigGrayTRCTag, (void*)tc));
cmsFreeToneCurve(tc);




-----Original Message-----
From: Marti Maria [mailto:mar...@li...] 
Sent: Dienstag, 24. Mai 2016 15:50
To: Marco Freudenberger; 'Florian Höch'; lcm...@li...
Subject: RE: [Lcms-user] How to create a gray profile with L-star grey response?

Right, mark the PCS as Lab and use cmdBuildGamma(NULL, 1.0). You only need to add the white point and this curve.

Marti Maria
The LittleCMS project
http://www.littlecms.com 

-----Original Message-----
From: Florian Höch [mailto:lis...@ho...]
Sent: martes, 24 de mayo de 2016 15:19
To: lcm...@li...
Subject: Re: [Lcms-user] How to create a gray profile with L-star grey response?

Hi,

Am 24.05.2016 um 15:07 schrieb Marco Freudenberger:
> PS - to the group: I'm still wondering what would happen if I'd simply 
> set
the TransferFunction to NULL...

That would result in a gamma 1.0 response I think (according to the ICC spec).

Florian.

----------------------------------------------------------------------------
--
Mobile security can be enabling, not merely restricting. Employees who bring their own devices (BYOD) to work are irked by the imposition of MDM restrictions. Mobile Device Manager Plus allows you to control only the apps on BYO-devices by containerizing them, leaving personal data untouched!
https://ad.doubleclick.net/ddm/clk/304595813;131938128;j
_______________________________________________
Lcms-user mailing list
Lcm...@li...
https://lists.sourceforge.net/lists/listinfo/lcms-user

Re: [Lcms-user] How to create a gray profile with L-star grey response?

[Marti M. <mar...@li...>]

Right, mark the PCS as Lab and use cmdBuildGamma(NULL, 1.0). You only need
to add the white point and this curve.

Marti Maria
The LittleCMS project
http://www.littlecms.com 

-----Original Message-----
From: Florian Höch [mailto:lis...@ho...] 
Sent: martes, 24 de mayo de 2016 15:19
To: lcm...@li...
Subject: Re: [Lcms-user] How to create a gray profile with L-star grey
response?

Hi,

Am 24.05.2016 um 15:07 schrieb Marco Freudenberger:
> PS - to the group: I'm still wondering what would happen if I'd simply set
the TransferFunction to NULL...

That would result in a gamma 1.0 response I think (according to the ICC
spec).

Florian.

----------------------------------------------------------------------------
--
Mobile security can be enabling, not merely restricting. Employees who bring
their own devices (BYOD) to work are irked by the imposition of MDM
restrictions. Mobile Device Manager Plus allows you to control only the apps
on BYO-devices by containerizing them, leaving personal data untouched!
https://ad.doubleclick.net/ddm/clk/304595813;131938128;j
_______________________________________________
Lcms-user mailing list
Lcm...@li...
https://lists.sourceforge.net/lists/listinfo/lcms-user

Re: [Lcms-user] How to create a gray profile with L-star grey response?

[Florian H. <lis...@ho...>]

Hi,

Am 24.05.2016 um 15:07 schrieb Marco Freudenberger:
> PS - to the group: I'm still wondering what would happen if I'd simply set the TransferFunction to NULL...

That would result in a gamma 1.0 response I think (according to the ICC
spec).

Florian.

Re: [Lcms-user] How to create a gray profile with L-star grey response?

[Marco F. <Mar...@en...>]

Hi !

Thanks for your response,

looks like I'm on the right path, your solution looks pretty similar - and BTW, I take your comment that you are no expert as an understatement, I've visited your website a couple of times and think it's a great reference and shows a lot of knowledge and experience :-)

Regarding my last parameter value:
I indirectly took it off Bruce Lindbloom's site as well :-) Unfortunately, I missed the page you linked with the "Inverse Companding" somehow, I started at the "(forward) Companding" page (http://brucelindbloom.com/index.html?Eqn_RGB_to_XYZ.html) and did the math to revert it.

For the last parameter I started with:
e(epsilon) = 0.008856, K(kappa) = 903.3 
so I'm calculating: e' = e * K / 100.0 (as e <= e). It's very close to 0.08 anyways :-)

However, I used the numbers that Bruce lists as "Actual CIE Standard". Thanks to your second link (and I've seen that page before, but didn't remember it when I needed it ...) I realized that the values given as "Intent of the CIE Standard" as you are using them are probably the better values... and with e = 216/23489 and K = 23489/27, e' turns out to be 216/2700 = 2/25 = exactly 0.08...

Thanks and best regards,
Marco

PS - to the group: I'm still wondering what would happen if I'd simply set the TransferFunction to NULL...









-----Original Message-----
From: Elle Stone [mailto:ell...@ni...] 
Sent: Dienstag, 24. Mai 2016 14:08
To: lcm...@li...
Subject: Re: [Lcms-user] How to create a gray profile with L-star grey response?

On 05/24/2016 06:54 AM, Marco Freudenberger wrote:
> Hi!
>
> I'm trying to create a gray profile that has an L* (L-star) response 
> curve, but I'm a little confused about the "parametric tone curve" syntax.
>
> Is there an example how to create the correct tone curve? I guess I 
> need the inverted version of L* companding, right? Would that be a 4 
> parametric curve, with:
>
> y(Gamma) = 3.0
>
> a=1.0/1.16
>
> b=0.16/1.16
>
> c=100.0/903.3
>
> d=0.008856*903.3/100.0
>
> So in code something like that:
>
> cmsFloat64Number lStarParams[5] = { 3.0, 1.0/1.16, 0.16/1.16, 
> 100.0/903.3, 0.008856*903.3/100.0 };
>

FWIW (I'm no expert!), I use these parameters to make the Lab parametric
curve:

cmsFloat64Number labl_parameters[5] =
{ 3.0, 1.0/1.16, 0.16/1.16, 2700.0/24389.0, 0.08000 };

The parameters are from these two pages:

http://brucelindbloom.com/index.html?Eqn_RGB_to_XYZ.html
http://brucelindbloom.com/index.html?LContinuity.html

Where does the equation for your last parameter come from? I've always used Lindbloom's values and he gives 0.08.

Best,
Elle
--
http://ninedegreesbelow.com
Color management and free/libre photography

------------------------------------------------------------------------------
Mobile security can be enabling, not merely restricting. Employees who bring their own devices (BYOD) to work are irked by the imposition of MDM restrictions. Mobile Device Manager Plus allows you to control only the apps on BYO-devices by containerizing them, leaving personal data untouched!
https://ad.doubleclick.net/ddm/clk/304595813;131938128;j
_______________________________________________
Lcms-user mailing list
Lcm...@li...
https://lists.sourceforge.net/lists/listinfo/lcms-user

Re: [Lcms-user] How to create a gray profile with L-star grey response?

[Elle S. <ell...@ni...>]

On 05/24/2016 06:54 AM, Marco Freudenberger wrote:
> Hi!
>
> I'm trying to create a gray profile that has an L* (L-star) response
> curve, but I'm a little confused about the "parametric tone curve" syntax.
>
> Is there an example how to create the correct tone curve? I guess I need
> the inverted version of L* companding, right? Would that be a 4
> parametric curve, with:
>
> y(Gamma) = 3.0
>
> a=1.0/1.16
>
> b=0.16/1.16
>
> c=100.0/903.3
>
> d=0.008856*903.3/100.0
>
> So in code something like that:
>
> cmsFloat64Number lStarParams[5] = { 3.0, 1.0/1.16, 0.16/1.16,
> 100.0/903.3, 0.008856*903.3/100.0 };
>

FWIW (I'm no expert!), I use these parameters to make the Lab parametric 
curve:

cmsFloat64Number labl_parameters[5] =
{ 3.0, 1.0/1.16, 0.16/1.16, 2700.0/24389.0, 0.08000 };

The parameters are from these two pages:

http://brucelindbloom.com/index.html?Eqn_RGB_to_XYZ.html
http://brucelindbloom.com/index.html?LContinuity.html

Where does the equation for your last parameter come from? I've always 
used Lindbloom's values and he gives 0.08.

Best,
Elle
-- 
http://ninedegreesbelow.com
Color management and free/libre photography

[Lcms-user] How to create a gray profile with L-star grey response?

[Marco F. <Mar...@en...>]

Hi!

I'm trying to create a gray profile that has an L* (L-star) response curve, but I'm a little confused about the "parametric tone curve" syntax.

Is there an example how to create the correct tone curve? I guess I need the inverted version of L* companding, right? Would that be a 4 parametric curve, with:
y(Gamma) = 3.0
a=1.0/1.16
b=0.16/1.16
c=100.0/903.3
d=0.008856*903.3/100.0

So in code something like that:
cmsFloat64Number lStarParams[5] = { 3.0, 1.0/1.16, 0.16/1.16, 100.0/903.3, 0.008856*903.3/100.0 };
cmsBuildParametricToneCurve( ctx, 4, lStarParams );
???

Or is it as easy as passing a NULL for the TransferFunction parameter in cmsCreateGrayProfileTHR() because the response matches the PCS response?

Thanks,
Marco

Re: [Lcms-user] Question about Python bindings for lcms2

[John J. <joh...@gl...>]

On 28/09/2015 21:33, Kunda wrote:
What is the status of Python bindings for lcms2?
Is anyone working on this?

Hi, this is rather late, but if you haven't anything else you could try the SWIG bindings at https://pypi.python.org/pypi/littlecms/0.1b1. The documentation is lacking but it's mostly just like using the C API. The biggest tricky bit is understanding the use of the array objects that are necessary for passing as params to many C functions. The tests do cover quite a lot ground so I hope you won't find much trouble using it.

There is a source distribution which has been tested on Windows and Linux. On Windows you'll need either Visual Studio 2015, 2010, or 2008 depending on your Python version. The bindings will build and install automatically if you use pip to install it. There is also a pre-built wheel for Python 3.5 on Win64 which will install automatically with pip.

I've only tested with Python 3 because that's what I use. I believe it will be only a smallish effort to make it work on Python 2.

John

[Global Graphics at drupa 2016 - visit us at Hall 7 Stand B21/C20]<http://www.globalgraphics.com/company/events/drupa>