To realize small-aperture cameras with the same resolving power as large-aperture cameras, a high-resolution imaging technology based on pixel coding is proposed. To reduce image aliasing at high and low frequencies, a pixel coding algorithm based on the system point spread function as the computing core is proposed. First, the encoding matrix of the system is directly constructed in the spatial domain. Then, the inversion method is used to decode the output image for enhanced image quality. Finally, the imaging system with a focal length of 100 mm and a pixel size of 9 μm is developed. The F-numbers of 11 (F11) and 25 (F25) are used for indoor experimental verification. The pixel coding algorithm is used to correct the image of distinguish plate obtained using the F25 system. The value of the corrected modulation transfer function (0.18) is equivalent to that obtained using the F11 system(0.24), and high image contrast is obtained. The experimental results verify the feasibility and effectiveness of the pixel coding algorithm, thereby allowing small-aperture cameras to achieve high-resolution imaging.