A Low-Complexity End-to-End Stereo Matching Pipeline From Raw Bayer Pattern Images to Disparity Maps

Conventional computer vision algorithms, including stereo matching algorithms, take finely rendered color images as input. However, existing image signal processing (ISP) pipelines for color image generation are designed for photography with a goal of generating pleasing images for human eyes. This paper describes a new end-to-end pipeline for stereo matching from raw Bayer pattern images to disparity maps with customized ISP. Unlike conventional stereo matching systems which need a complete ISP module to render full-size standard RGB (sRGB) images, a subsampling-based demosaicing-downsampling (SDD) operation is introduced in the proposed pipeline to demosaic and downsample the Bayer pattern images. The resultant half-size color image pairs are processed with simple denoising and tone mapping algorithms to generate the final input images of stereo matching algorithms. It is found that the simple nearest neighbor upsampling method is good enough to generate the final full-size disparity maps. Experimental results show that the proposed pipeline is capable of generating comparable or even better stereo matching results than the conventional pipeline. By skipping most of the unnecessary ISP steps and reducing the size of input images, the computational complexity of the end-to-end stereo matching pipeline is significantly reduced.