井下电视图像压缩技术

测井电缆的数据传输带宽非常有限,图像压缩是井下电视研制的关键技术.基于小波变换的井下电视图像压缩系统通过小波变换、子带编码、自适应量化和熵编码进行图像压缩,采用质量盒控制、背景对比度控制和场频控制技术,实现了较高的压缩比.该系统采用DSP控制技术和图像压缩专用芯片,使图像压缩比和数据流量易于控制,适用于单芯电缆、多芯电缆和光电测井电缆的图像传输.图像解压缩回放过程中采用了插场技术,实现了PAL制式视频50场/秒的实时运动图像播放速度.

Data compression technique of downhole video image

The bandwidth for the data transmission of logging cable is very limited,so image compression is the key technology to the development of a downhole video.A down-hole video image compression system based on wavelet transform is developed.It accomplishes the compression of video images by wavelet transform,subband coding,adaptive quantization and entropy coding,and it achieves to a very high compress ratio.The DSP technology and special image compression IC used in the system makes the compression ratio and data stream easy to be controlled.The down-hole video image compression system is suitable to the data transmission single-core cable,multi-core cable,or photoelectric logging cable.A field insertion technology is used in the decompression and playback of the video image,and the real-time playing speed of 50 fields per second of PAL system video is realized.