pigment vs color in

pigment is a noun but color in is not a noun.

Word	Noun	Adjective	Verb	Adverb
pigment	Yes	No	Yes	No
color in	No	No	Yes	No

As verbs, color in is a hypernym of pigment; that is, color in is a word with a broader meaning than pigment:

Other hypernyms of pigment include color, colorise, colorize, colour, colour in, colourise, colourize.

pigment (noun)	color in (noun)
a substance used as a coating to protect or decorate a surface (especially a mixture of pigment suspended in a liquid); dries to form a hard coating
dry coloring material (especially a powder to be mixed with a liquid to produce paint, etc.)
any substance whose presence in plant or animal tissues produces a characteristic color

pigment (verb)	color in (verb)
color or dye with a pigment	add color to
acquire pigment; become colored or imbued