To capture images of the internal surface vascular tissue of the human body under small cavity conditions, accurately present the state of vascular tissue, and address issues related to the large size of conventional image detectors, poor imaging quality under uneven lighting conditions, and low contrast of vascular imaging, an electronic endoscopic image acquisition system is designed. This system uses an OV6946 ultra-small image detector with a 300?1100 nm-wide spectrum imaging capability and is driven by a domestic Pangu FPGA. By improving the contrast-constrained adaptive histogram equalization (CLAHE) algorithm, vascular images on the surface of small cavity tissues in human can be effectively enhanced. The proposed system provides superior imaging performance for tissue imaging within small cavities under nonuniform illumination. The improved CLAHE image enhancement algorithm significantly enhances the contrast of vascular tissue imaging, providing an effective technical solution for advancing medical ultrafine electronic endoscopic systems or broadband image enhancement systems with similar requirements.