A subjective bit allocation method is proposed to improve the efficiency of region of interest ( ROI) based coding stereoscopic images in the paper. The method is described with the two designed subjective experiments as below. Experiment I is to evaluate the visual quality of distorted stereoscopic images in ROI based coding using variety of bit allocation schemes. Experiment II makes paired comparison to all the distorted stereoscopic images. The experimental results show that a strategy for bit allocation is very important to ROI based coding, and bit allocation is relevant to image quality level but not to image contents. When stereoscopic images are coded with four different quality levels, whose ROI quantized parameter (QP) values are 22, 27, 32, 37, the differences of QP values between ROI and non-ROI in the corresponding reasonable schemes are 9, 6, 3, and 3 , respectively. The determination of the QP difference will guarantee the overall subjective quality of stereoscopic images and the improvement of coding efficiency.%为了提高基于感兴趣区域(ROI)的立体图像编码的效率,从人眼视觉感知的角度提出了一种探寻合理的立体图像比特分配策略的方法.该方法设计了两个主观实验,其中实验I对各种比特分配策略下的失真立体图像进行视觉质量评价,而实验II在实验I的基础上对所有失真立体图像进行两两对比实验.实验结果表明:合理的比特分配策略对基于ROI的立体图像编码至关重要,且与图像内容无关,但与立体图像质量档次有关；在立体图像ROI采用量化参数(QP)为22、27、32、37的4种不同质量档次编码时,对应的合理分配策略下非ROI与ROI之间QP差异值分别约为9、6、3、3；立体图像ROI与非ROI比特分配策略的确定,能够在保证立体图像整体主观质量不变的同时有效地提高立体图像的编码效率.
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