An image pre-processing method based on shearlet transform was proposed.First

image was decomposed by shearlet transform

then to get the subband coefficients

Bayesian statistics and threshold shrinkage methods were used in the low-frequency component and high—frequency components

through shearlet reconstruction

the predicted background of the image was obtained

the original image is subtracted by the predicted background image and we can get the result image

Finally

in order to test the new method

classical adaptive threshold segmentation was used to segregate the targets.Theoretical analysis and experimental results show that

compared with several commonly used methods

ISNR of result image which using the new method is higher than the others

and have better effects both in objective evaluation and the subjective vision.