Provided are an apparatus and method for enhancing an image using a color channel. A pre-processing unit generates an inverted image by inverting a luminance component estimated from a red (R) channel among color channels of a red, green, and blue (RGB) color space of an input image. A channel merging unit generates a merged luminance (L) channel by merging an L channel of an International Commission on Illumination (CIE) L*a*b* (CIELab) color space of the input image and the inverted image. A contrast enhancement unit enhances contrast by expanding a histogram of the merged L channel. A color restoration unit combines the merged L channel whose contrast has been enhanced and chromaticity components of the input image, and converts a resultant color image to the RGB color space, thereby generating a restored image.