"predominant colors" is a correct and usable phrase in written English. You can use "predominant colors" to refer to the colors that are most prominent or plentiful in a particular location or object. For example: "The predominant colors in the living room are shades of blues and greens.".
The three predominant colours of this film are black, white and green.
Look very carefully at each area of the still life, noting the predominant colours and their relative temperature differences and overtones.
There is a joyfulness about the plums, garlic, pears, grapes and lemons as well as eggs and mackerel which appear on his kitchen tables of these years (an example at the Tate is Still Life with Candlestick, 1949-50); the predominant colours of which are muted light blues, yellows and greys.
The design was based on a colour scheme of deep red and gold, inspired by the predominant colours of Red Square, the Kremlin and the gold domes of Moscow's cathedrals, and featured images of the Moscow skyline, as well as the UEFA Champions League logo and trophy rendered in a Russian artistic style, with text in a font similar to Cyrillic script.
Predominant colour: grey.
Green is the predominant colour.
White has become the predominant colour.
Ludwig does not simply clarify my doubts with English writing, it enlightens my writing with new possibilities
Simone Ivan Conte
Software Engineer at Adobe, UK