  Form factors, as quantities involving both local operators and asymptotic
particle states, contain information of both the spectrum of operators and the
on-shell amplitudes. So far the studies of form factors have been mostly
focused on the large Nc planar limit, with a few exceptions of Sudakov form
factors. In this paper, we discuss the systematical construction of full color
dependent form factors with generic local operators. We study the color
decomposition for form factors and discuss the general strategy of using
on-shell unitarity cut method. As concrete applications, we compute the full
two-loop non-planar minimal form factors for both half-BPS operators and
non-BPS operators in SU(2) sector in N=4 SYM. Another important aspect is to
investigate the color-kinematics (CK) duality for form factors with high-length
operators. Explicit CK dual representation is found for the two-loop half-BPS
minimal form factors with arbitrary number of external legs. The full-color
two-loop form factor results provide an independent check of the infrared
dipole formula for two-loop n-point amplitudes. By extracting the UV
divergence, we also reproduce the known two-loop non-planar SU(2) dilatation
operator. As for the finite remainder function, interestingly, the non-planar
part is found to contain a new maximally transcendental part beyond the known
planar result.
