[argyllcms] Re: Generating a target from a reference file

  • From: Pascal de Bruijn <pmjdebruijn@xxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Fri, 27 Mar 2009 18:03:39 +0100

On Fri, Mar 27, 2009 at 5:59 PM, Pascal de Bruijn <pmjdebruijn@xxxxxxxxx> wrote:
> On Thu, Mar 26, 2009 at 9:16 PM, Pascal de Bruijn <pmjdebruijn@xxxxxxxxx> 
> wrote:
>> On Thu, Mar 26, 2009 at 9:01 PM, Pascal de Bruijn <pmjdebruijn@xxxxxxxxx> 
>> wrote:
>>> On Thu, Mar 26, 2009 at 6:56 PM, Lars Tore Gustavsen
>>> <lars.tore@xxxxxxxxxxxxxx> wrote:
>>>> On Thu, Mar 26, 2009 at 6:01 PM, Pascal de Bruijn <pmjdebruijn@xxxxxxxxx> 
>>>> wrote:
>>>>> On Thu, Mar 26, 2009 at 2:22 PM, Graeme Gill <graeme@xxxxxxxxxxxxx> wrote:
>>>>>
>>>>>
>>>>>>> Not exactly, preferably to RGB... Not all image editor can handle Lab.
>>>>>>>
>>>>>>> And I'd like to read back the RGB, to generate a newly (edited),
>>>>>>> reference file...
>>>>>>
>>>>>> I thought that's what I outlined last time.
>>>>>
>>>>> I'm probably confusing terminology, which in turn is confusing you :)
>>>>>
>>>>> The point of the exercise would be to read back the edited image,
>>>>> as a new similar (but edited) reference file.
>>>>>
>>>>> 1. Convert R080505.txt into an image of an IT8 chart, with the patch 
>>>>> colors
>>>>> generated from the text file.
>>>>
>>>>
>>>> I just had to play with this. Do you mean something like this:
>>>>
>>>> sed   -n '17,304p' R080505.txt |awk '{print "convert -colorspace LAB
>>>> -size 118x94 \"xc:LAB("$5"%,"$6"%,"$7"%)\" " $1".png\n"}' > run.sh
>>>>
>>>> Then you have to join them. I think there is a hint for that in the
>>>> url posted above. I have to play with the kids now..
>>>
>>> I was already fiddling with your scripts, adapting it. I attached my
>>> results. And
>>> scanin does recognize the image.
>>>
>>> Now I need to see if I can read back the image as a reference file, with
>>> (nearly) identical values. But that's something for tomorrow.
>>
>> Scanning back isn't that hard. I've included that script as well.
>>
>> However, for the conversion from the reference file, to the image, I have
>> no explicit color space defined. So that's probably why the read back
>> data it's matching the original data.
>
> I'm finding it hard, to get the same values read back...
>
> Also, the generated image seems yellowish... Possibly because of a
> whitepoint mismatch?
>
> When converting from XYZ imagemagick seems to output Linear RGB,
> but in what color space... Anybody have a good guess?

Well isn't this typical... Minutes are mailing the previous post, I keep on
fiddling a bit, and using ProPhotoRGB (ROMM), without gamma correction,
completely solves my issues, and the original values are read  back.

Regards,
Pascal de Bruijn

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