Infrared weak and small target preprocessing method and device based on improved bilateral filtering

The invention discloses an infrared weak and small target preprocessing method and device based on improved bilateral filtering, and the method comprises the following steps: background suppression: comparing a background and noise part in an infrared image into a foggy part in a foggy day image according to an infrared image model, and obtaining a foggy part in the foggy day image through applying an image defogging algorithm to the infrared image; darkening the foggy part (background and noise) to obtain a background-suppressed dark image; improved bilateral filtering: background noise is suppressed by using the improved bilateral filtering, approximate high-dimensional filtering is carried out by using a weighted combination of fast convolution, bilateral filtering is carried out by using an isotropic Gaussian range kernel, and finally a dark image with an enhanced local signal-to-noise ratio of a target and a background is obtained; and evaluation indexes: calculating a peak signal-to-noise ratio, structu