基于HSI色彩空间的低照度图像增强算法

Low Illumination Image Enhancement Algorithm Based on HSI Color Space

为了提高低照度图像的质量,提出了基于HSI色彩空间的图像增强新算法。首先将待增强的彩色图像转换到HSI色彩空间,然后分别针对饱和度分量(S)和亮度分量(I)进行不同的增强处理。对分量S提出分段指数变换进行增强,以使图像色彩更适合人眼视觉习惯;对分量I,引进新的正交多小波V-系统,先进行相应的V-变换,分离出高、低频子带,接着对低频子带进行Retinex调整,以减轻光照因素对图像的影响,而对高频子带则使用改进的模糊增强算法来实现图像的去噪与增强。最后将处理后的分量S、分量I与分量H合成为清晰的彩色RGB图像。实验表明该算法可以明显改善低照度彩色图像的视觉效果,在客观评价指标上也有显著提高。

To improve the quality of low illumination image,a new image enhancement algorithm based on HSI color space is proposed.First,we convert the RGB image into the HSI color space,and then perform enhancement to the saturation S and brightness I respectively with different methods.To make the image more suitable for human visual habit,piecewise exponential transformation is used for the enhancement of the saturation component S.While the V-system,a new orthogonal multi-wavelet,is introduced for the enhancement of the luminance component I.First,we perform V-transform to the luminance I to isolate the high,low frequency sub-bands.And then process Retinex adjustment to the low-frequency sub-band to reduce the influences of illumination to the image,while we use improved fuzzy enhancement to the high frequency sub-band to achieve image denoising and enhancement.Finally,the processed S,I and H components are synthesized into a clear RGB image.The experiment results show that our algorithm can obviously improve the visual effect of the low illumination color image,and also has significant improvement in the objective evaluation indexes.