1. An object-tracking method in an environment of multiple non-overlapping cameras, comprising: dividing color rendering values required to represent colors into a plurality of sub-color regions; converting Red, Green, Blue (RGB) pixels of objects present in a first image and a second image acquired by cameras into first hue values and second hue values, respectively; assigning the first hue values to first sub-color regions, and then generating a first color histogram for a first sub-color region set by extracting the first sub-color region set among the first hue values assigned to the sub-color regions, the first sub-color region set having hue values equal to or greater than a first predetermined value; assigning the second hue values to second sub-color regions, and then generating a second color histogram for a second sub-color region set by extracting the second sub-color region set among the second hue values assigned to the sub-color regions, the second sub-color region set having hue values equal to or greater than a second predetermined value; extending an area of the first color histogram to a predetermined width; determining whether the second color histogram is included in the extended area of the first color histogram; and determining that the object in the first image is identical to the object in the second image if the second color histogram is included in the extended area of the first color histogram, wherein the first predetermined value is an average value of the first hue values and the second predetermined value is an average value of the second hue values.