Illumination estimation is most important

step in color constancy computation. Although a number

of elaborate algorithms were proposed, methods like

grey world and Max RGB are still widely used because of

their low computational costs. The grey world algorithm

is based on the grey world assumption: the average reflectance

in a scene is achromatic. But this assumption

can not be always satisfied well. Borrowing on some of

the strengths and simplicity of the grey world algorithm,

we propose a novel algorithm called Illumination estimation

based on color invariant (IECI) to improve the performance

of grey world, in which the achromatic surfaces

are identified for illumination estimation. As we know, the

color of achromatic surface can completely reflect the illumination

color incident on the scene. In light of this idea,

color invariant technique is introduced to approximately

identify the achromatic surfaces, then iterative method is

used to improve accuracy of the proposed method. The experimental

results show that the proposed algorithm can

get satisfying results and outperforms some current stateof-

the-art color constancy algorithms.