Dear Nirmillo,

Welcome to the field of technical colour-identity definition and colorimetry. The L*a*b* model firstly establishes an academically verifiable reference basis for modeling colour. Secondly it enables visual colour matches to be identified and specified. Further, it quantifies a reasonably uniform scaling of colour difference that can be used to establish colour match pass/fail tolerances; and finally it enables industrial colourists to predict and manufacture visually colour matched products. The following paper by Roy Berns is a general introduction to colorimetry that you may find useful:-

A generic Approach to Color Modeling RS Berns - Color Research & Application Volume 22, Issue 5, October 1997, Pages 318-325.

Regards

David.

Thank you very much sir. Out of curiosity, I have done some research on color index based chlorophyll determination in plant and found superiority of Lab color model. Before doing the work, I did literature review regarding color models and previous methods of chlorophyll measurement and somewhere, I forget now, found the device independence of Lab color model. But, now what I have found out that their source of claim is not so strong. Therefore, I need a strong reference of this claim.

The numeric basis of the device independent L*a*b* model is the CIE Standard Observer definition of colour identity in the human visual response to light stimuli. The CIE (Commission Internationale d’Eclairage or International Illumination Committee) is an international body with world-wide support which is responsible for defining and validating the basis of colour science in general. The necessary detail is provided in the official publications of the Central Bureau in Vienna, such as Publication CIE No. 15.2 'CIE Colorimetry'.

If now you visualise these colour identities to be distributed in a three-dimension ‘colour space’, the parameters L*, a*, b* become a set of co-ordinates that specify its scalar basis and quantify the visual differences between them. The actual scalar values in each L*, a*, b* dimension were quantified experimentally in a whole series of 'Colour Difference' related papers. In each case the reference basis was a very large data set of surface-colour sample pairs and the instance of visual difference thus observed.