Re: [Lcms-user] restricted ICC Profile AND lcms2

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

Hi Winfried,

The color manager can help to make things easier.

Please take a look on this algorithm:

- Open the jpeg2000 file

- Is that a 16 bit rgb image?
       yes: input format = TYPE_RGB_16
- Is that a 16 bit gray image?
      yes: input format = TYPE_GRAY_16
- Is that  a 8 bits RGB image ?
     yes: input format = TYPE_RGB_8
... and so one ...

- Is there any embedded profile? 
           yes: use it  as input
           no: use some predefined default profile, on depending on the 
input space

output format = TYPE_BGR_8
- Do you have profile for your monitor?
  yes: use it as output
  no: use sRGB built-in

- Transform the image from input profile, input format to output 
profile, output format
by calling cmsCreateTransform(), cmsDoTransform()

- Do a cleanup

That's all. And with such simple algorithm you have true color 
management, and automatic
support of 8 and 16 bits for grayscale and RGB. You can also add support 
for CMYK
or any other space just adding more input cases.

Regards
Marti.


szu...@ar... wrote:
>> Marti wrote:
>> You are assuming that to do a color transform, both input and output
>> profiles have to be of same colorspace, but that's not true.
>>     
>
> For the file:
> file7.jp2: color-space(RGB ) profile-connection-space(XYZ )
>           16-bit e-sRGB JP2 restricted (to sRGB) profile)
>
> I coded:
>
>    inprof = cmsOpenProfileFromMem(jp2_profile_buf, jp2_profile_len);
>    outprof = cmsCreate_sRGBProfile();
>    inspace = cmsGetPCS(inprof);
>    outspace = cmsGetColorSpace(outprof);
>
> As the inspace is (XYZ ) and the outspace is (RGB ), I supposed I
> I had to write:
>
>    transform = cmsCreateTransform(in_prof, TYPE_XYZ_16,
>      out_prof, TYPE_RGB_16, intent, 0);
>
> But I got no transform. I had to change the code to:
>
>    transform = cmsCreateTransform(in_prof, TYPE_RGB_16,
>      out_prof, TYPE_RGB_16, intent, 0);
>
>   
>> Incidentally, there is indeed a cmsCreate_GrayProfile()
>>     
> I meant a parameterless one like cmsCreate_sRGBProfile().
>
> Because I do not know how to transform the third file, file8.jp2:
> -------------- ICC Profile[414] ---------------
> cmmtype(0) version(2.32.0.0) class(scnr)
> color-space(GRAY) profile-connection-space(XYZ )
> date(23.1.2002) time(9:26:16)
> signature(acsp) platform-signature()
> profile-flags(0x1) [0]1 [1]0 [2:15]0
> device-attr(0) white(0) negative(0) matte(0) transparent(0)
> rendering-intent(0)
> CIE: x(0.63190) y(1.0) z(0.54061)
> [0]signature(desc) size[154]
>   Restricted ICC profile describing greyscale version of ROMM-RGB
> [1]signature(cprt) size[42]
>   Copyright 2001 EKC-RICC Reference
> [2]signature(wtpt) size[20]
>   XYZ(0.214, 0.214, 0.214)
> [3]signature(kTRC) size[14]
>   curv size[1]
>     curv[0]gamma(1.205)
> -----------------------------------------------
> There is only one channel. I have no 'outprof'.
>
> The two other images, using lcms-2.0, now look enchanting.
>
> winfried
>
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