Re: Finding CIELab Values from Target Chart TIF
Re: Finding CIELab Values from Target Chart TIF
- Subject: Re: Finding CIELab Values from Target Chart TIF
- From: Peter Skarpetis <email@hidden>
- Date: Thu, 29 Apr 2010 20:15:34 +1000
On 29/04/2010, at 7:29 PM, Joseph Yates wrote:
>>
>> >> Can you describe this process in more detail? If I have the CMYK value of
>> >> Patch 130 of 0/0/0/100% - how do I use ColorSync utility to get a more
>> >> precise Lab value?
>>
>>
>> >It is very simple really. Just launch the Colorsync utility, click on the calculator tab,
>> >put in a CMYK profile for the process you are trying to simulate,
>>
> Well AFTER the printers are calibrated by the PhaserMatch software – I’m using a device link to “simulate” ISOCoatedv2 on the printers.
> Would this be the CMYK profile I would use in the ColorSync utility?
Yes it would. this would give you the expected Lab values of the patches on the printed sheet, after calibration.
>
> But since I send the 140 Patch Chart CMYK TIF file to the printer during the PhaserMatch calibration procedure – with the driver settings set to NONE (no color management) - aren’t the cmyk, lab value pairs that you described PhaserMatch using to make the transforms different than the cmyk, lab values I will obtain using a profile like ISOCoated v2 in ColorSync utility?
>
The calibration step is just to calculate then Lab -> CMYK lookup table. After that, when colour management is on, the source icc profile (ISOCoated v2) is used to convert the input cmyk values to Lab. Those Lab values are then put through the profile you created and out comes cmyk values that are sent to the printer driver.
Peter
> Or should I be using a ICC profile for the Phaser printer (Media Type/PQ setting) that I’m calibrating for?
>>
>> >select Lab as the output and then type in some cmyk values.
>> >Just remember that values are between 0 and 1, so for 50% you would enter 0.5,
>> >for 100.0 0.1 etc.
>> >It is a bit of a manual process, but it should provide what you want.
>>
>> >Peter
>>
> Yes I can see that it’s a bit of a process – but thanks – it does look like it will provide me with more precise Lab values.
>
> Joseph
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