Human chromosomes contain important information for cytogenetic analysis. Cytogenetic compares their patient's chromosome images against the prototype human chromosome band patterns. Chromosome images were acquired by microscopic imaging of metaphase or prophase cells on specimen slides. Digitized chromosome images usually are suffered from poor image quality, lack of contrast and hole in images. Therefore, the images must be enhanced. This paper presented an enhancement algorithm for chromosome images based on histogram equalization (HE) OTSU flood-full and dilations. Firstly, the histogram equalization is used to improve the contrast of the image. Then the OTSU threshold segment, flood-fill fill hole in image and dilation are experimented to validate the effect of this algorithm, the canny edge detection and oriented bounding box were used to detect the edge and segment chromosomes from background. A success rate of the proposed method can be improved to 97.07% of the enhancement in the chromosome images.