DIVA-extract luminance values from FALSE COLOR IMAGE

Hi there,

I am trying to generate a luminance database using VISUALIZATION diva object. The main problem regards to VISUALIZATION object only delivers a false color image but not its building data (database).

I am thinking could be possible reading each color from pixel (rgb) and to convert it on luminance data (cd/m2) using the given color graphic scale.

At the moment I am reading false color image and getting color data from pixels througth python component.

Somebody now what kind of equation do I have to use to translate RGB info into luminance data (cd/m2)? (regards to graphic scale)
Thank you all!