基于人眼视觉特性的印刷图像压缩技术研究

Compression Technology of Printed Image Based on Human Vision Characteristics

利用人眼对比度感知特性,计算了包装印刷图像的最小感知觉察误差阈值,通过阈值对图像的DCT变换系数进行量化,再采用Huffman编码方法实现编码,并通过实验验证。实验获得其峰值信噪比为49.647 1dB,压缩比达到11.497 7,编码效率达到0.743 8,即从客观评价上衡量数据压缩性能的指标均达到了较好的效果,证明了解码图像与原始图像间的差异较小,且从主观上人眼几乎不能分辨其差异,说明图像使用的压缩技术不会对图像的品质产生影响。该压缩算法既能达到一定的压缩效果,又能不影响包装印刷图像的观测效果,所以能够较好地满足包装印刷图像传输的要求。

The minimum detection error threshold of packaging and printed image perceived by human eye was calculated according to contrast detection characteristics of human eye.The DCT transform coefficients of image were quantified according to threshold value,encoded with Huffman coding method,and verified with experiments.The results showed that PSNR got to 49.647 1 dB;compression ratio was 11.497 7;and coding efficiency was 0.743 8.The result indicated that performance parameters of objective evaluation for data compression achieved better effect,and difference was little between the image decoded and the original image.From subjective evaluation,the eye could hardly distinguish the differences,which indicated that the image compression technology used did not affect the quality of the image.Results also showed that the compression algorithm can not only achieve some compression ration,but also does not affect the observed effect of printed image,so that it can satisfy the requirements of packaging and printing image transfer.