Abstract: Aiming at the problems of serious grayscale loss from high grayscale image enhancement algorithm in the existing pseudo-color methods,a pseudo-color enhancement algorithm suitable for super 8-bit high grayscale images was proposed,in which the traditional JET,HSV,and Rainbow coding were improved.The bit-depth quantization of high-bit grayscale image was performed.The high-grayscale enhancement algorithm was constructed to achieve color enhancement.A post-enhancement coefficient was introduced,improving visual effect of enhanced color image without losing much image information,from which image details and enhanced color contrast were preserved.To verify the effectiveness of this method,the algorithm was applied in the visual enhancement of the weld seam from oil pipeline X-ray film with low contrast and fuzzy defect information.The experimental results showed that the proposed method was very effective in the false color enhancement effect of high grayscale images.Compared with the existing algorithms,various indicators had been greatly improved.The grayscale loss,compared with the existing methods,was reduced from 93.774% to 68.75%;the time cost had also been decreased 80% at least;the number of hair colors had been increased by 3.4 times on the average at least.

Key words: high grayscale, image enchancement, X-ray weld defects, color number

摘要： 针对现有伪彩色方法在高灰阶图像增强中存在灰阶损失严重问题,提出一种适用于超8位高灰阶图像伪彩色增强算法,并改进了传统JET、HSV、Rainbow编码。首先,对高位灰度图像进行位深量化;其次,利用构造的高灰阶增强算法实现色彩增强;另外,引入一个后增强系数,保证在不损失较多图像信息的同时改善处理后色彩图像的视觉观感,以保留图像细节信息、增强颜色对比度;最后,为了验证所提方法的有效性,将其应用在低对比度、缺陷信息模糊的石油管道X射线底片的焊缝视觉增强上。实验结果表明,所提方法对高位灰度图像的伪彩色增强效果是非常有效的,相对于现有算法各项指标均有较大的提升,灰阶损失相对于现有方法从93.774%降低至68.75%,时间开销也降低了至少80%,发色数指标提升了至少3.4倍。

关键词: 高灰阶, 图像增强, X射线焊缝缺陷, 发色数