Abstract: An improved automatic color equalization is proposed for the contrast enhancement of grayscale and color images.A local filtering is performed firstly by taking account of the spatial distribution of grayscale or color in the image，and an improved relative lightness appearance function is employed.Then the dynamic range of the image is adjusted for the final result.In order to preserve the color of the original image，the HSV color space is employed and the filtering is carried out on the V-channel only.Experimental results demonstrate that the contrast can be effectively enhanced and no significant noise is introduced by this method.

Key words: image enhancement, automatic color equalization, contrast, noise control

摘要： 提出了一种改进的自动颜色均衡化方法，用于灰度和彩色图像对比度的增强。通过考虑图像中颜色或灰度的空间分布，首先对图像进行了局部自适应滤波，其中使用了改进的相对亮度表观函数。而后对图像进行动态范围调整以得到最终结果。在对彩色图像处理时，通过将图像从RGB空间转至HSV空间，仅对亮度通道进行滤波以保持颜色不失真。实验结果表明，方法可有效增强图像的对比度，且不会引入明显噪声。

关键词: 图像增强, 自动颜色均衡化, 对比度, 噪声控制