There is disclosed a method for converting color image data inputted from an
image input apparatus to a color space which is not dependent on the apparatus
and/or lighting with a high precision, the method comprising: setting a plurality
of sets of a subject as a main constituting element of an image inputted from the
image input apparatus, means for estimating color data which is not dependent on
the apparatus and/or the lighting for each set, judging whether or not each pixel
of the image data inputted from the image input apparatus belongs to the set of
the subject, and selecting the estimating means based on a judgment result to estimate
the color data which is not dependent on the apparatus and/or the lighting; learning
a distribution of a specified object for each set in the color space after color
conversion during color conversion of the image, performing tentative color conversion
from an input image signal, and using the signal after the tentative color conversion
to judge the set to which each pixel belongs in the color space after the color
conversion; or judging/indicating the set by a user, and subjecting each judged
set to a different color conversion processing.
