It depends on what primaries you choose for your OLEDs. AMOLED has perfect black levels (LCD technology does not) and near-perfect viewing angles. Unrealistic

It depends on what primaries you choose for your OLEDs. AMOLED has perfect black levels (LCD technology does not) and near-perfect viewing angles. Unrealistic colors are a problem of reproducing the information you acquire correctly. All of the colors humans can see are represented on the CIE 1931 chromaticity diagram. Choose any three points within that color space and draw a triangle between them. This colors within the triangle are those that the primaries at the vertices of the triangle can reproduce. The rest is just a software issue (controlling the correct voltages to each LED).