Mar 182011
 

Hi
I am creating color profile for inkjet printer
I want to know how to convert LAB to CMYK and reversion

Thanks a lot

This can be done through one of the Adobe type applications such as Photoshop, however it is very important that you understand that the result will depend on your colour management settings within the application. CMYK is device specific and NOT generic, and so to do this conversion properly you must first know the device profile for CMYK that you would like to convert your LAB data to.

The way an ICC profile is produced is by printing a “target” (a series of patches of colour that characterise colour on that device) on the printer, software and paper combination and then measure this back in using a spectrophotometer. After measuring this in the software that drives the printer (such as some rips) or the software that comes with the spectrophotometer will generate an ICC file that can be used for colour accurate printing.
This ICC profile is effectively a LUT (look up table) as an example, for LAB to CMYK or CMYK to LAB. to complete this conversion from a colour space other than LAB it requires 2 profiles – both an input and an output profile.

An example of typically how this works as follows:

CMYK > LAB < CMYK

or

RGB > LAB < CMYK

see also this website:
Learn> Colour> Basics> What is a “Colour / ICC Profile”

Please feel free to ask further if this is not entirely clear

  2 Responses to “How to convert LAB to CMYK”

  1. Can you help me convert these to …to CMYK for my printer. I cant seem to figure it out.
    Emerald Green
    L* 41.45 a* -8.28 b* 2.58 C* 8.67 h 162.70

    Sahara Tan
    L* 66.59 a* 5.81 b* 16.66 C* 17.64 h70.78
    Thank you

    • Hi Len,

      To answer you fully I would need a bit more info (such as what printing method / type & what software you use in your workflow).

      I will assume for now you are running a digital wide format printer with a proper rip software driving it:
      Your rip software that drives your printer should convert these automatically for you while processing your file based upon your media output profile.

      If for some reason you cannot do this, a work around would be to load in the relevant media profile into Photoshop’s CMYK default working space – THEN open a new document and use the colorpicker to enter the values above to get the CMYK results back.

      This should not ever be needed though because the best practice is as I first mentioned, your rip software that drive the printer is the best place for this conversion to happen.

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