Underwater Image Compression And Unequal Error Protection Based On Image Perceived Quality

Underwater images are widely applied in marine resource exploration,submarine topography survey,underwater target detection,and many other fields.Image compression and transmission are the important research content of underwater image communication system.Firstly,the perceived quality is used as the optimization goal of underwater image compression in this paper.In order to select the better indicators of the underwater compressed image quality,full reference image quality assessment methods are compared.Then,the adaptive compression method of underwater image based on the perceived quality prediction is established.The embedded coding compression and compression perception method are used in underwater image compression.After image compression quality curves being obtained,the laws between Image Activity Measurement(IAM)and BPP,image compression quality are summarized.The greater IAM,the more complex of image texture,the higher compression ratio is required for the reconstructed image with high quality.And vice versa,image with lower IAM can achieve the satisfied image quality under low compression ratio.PQoS exponential function is used to fit the curve of compression ratio and compression perceived quality.According to the corresponding relation between IAM and the image compression quality curve,linear fitting is used to fit the IAM and parameters of PQoS function,finally underwater image compression quality prediction function is established.Through calculating the IAM of underwater image,the corresponding compression quality curve can be obtained,the perceived quality of compression image is predicted without coding.Underwater acoustic channel is a stochastic channel with time,space and frequency varying,and the channel bandwidth is limited.The protection mechanism is adopt for image compression coding stream to overcome channel interference.The limited bandwidth resources should be allocated reasonably to make the reconstruction image satisfy visual demand.Therefore,the error robustness of different compression method in channel transmission is studied,LDPC channel coding and unequal error protection are adopted to protect the image transmission code stream.In order transmit the most image information under the condition of limited bandwidth,and according to different regions in the image block have different saliency,the saliency regions of image are coded by priority in SPIHT compression,and higher compression ratio is allocated to the significant region in compressive sensing algorithm.The experiment results show that two kinds of improved compression coding method can obtain higher quality of reconstructed image.