1. An auto white controlling method, comprising: dividing an image into a plurality of reference regions; dividing each of the plurality of reference regions into a plurality of sub-regions; for each of the reference regions, calculating a difference between a mean chroma of the reference region and a mean chroma of each of the sub-regions; and confirming that an object having dominant chroma is included in a reference region based on the calculated differences; providing a plurality of feature points having color features of the image if the image includes the object having the dominant chroma; detecting a first illuminant according to the plurality of feature points; calculating a mean chroma of data showing a chroma difference within a threshold value with a chroma of the first illuminant among data constituting the image; and providing a second illuminant by mapping the mean chroma to an illuminant locus.