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The result of target recognition is always influenced by clutter background,low contrast and deficiency luminance of image.Besides the factors mentioned above,detection and recognition of partial masked target has the character of imperfection and information loss of target,which leads to recognition problem.All the harmful factors cannot make target recognition be realized by hybrid optoelectronic joint transform correlator due to the weak correlation peaks or even no peaks.Aiming at this phenomenon,partial masked target image in hybrid optoelectronic joint transform correlator is processed by the method of adaptive threshold,and power spectrum is processed by Mexican wavelet transform.The combination depresses the noise disturbance effectively and enhances the energy of diffractive light of obscuration target and reference template.This enhances the contrast and energy of correlation peaks of partial masked target and improves the ability of detection and recognition for partial masked target with joint transform correlator.The experimental results show that the combination of adaptive threshold and Mexican wavelet transform can improve the ability of detection and recognition for partial masked target with hybrid optoelectronic joint transform correlator effectively.

Photo response non uniformity(PRNU) noise sets a fundamental limit on image sensor performance,especially under low illumination in remote sensing system.After introducing a complete noise model of time delay and integration charge coupled device(TDICCD),a complete model of TDICCD noise is proposed.Then PRNU noise model for all selectable integration stage is developed,which is linearly related to illumination.Moreover,exposure stages are taken into consideration due to their inherent averaging effect,and relationship between nonuniformity parameter and integration stage is developed.Finally a techinque to identify and measure the PRNU noise in TDICCD is presented by analysis of the output images,and the experimental results are illustrated from test system,measured PRNU noise at different illumination and integration stages are also analyzed.

In sub-aperture stitching system,image quality will be affected directly by tilt and shift errors of sub-apertures.The equivalent nodal point concept of dynamic optics was applied.During alignment of sub-aperture stitching system,if the sub-aperture was tilted and shifted,the circle center of sub-aperture would be tilted and shifted consequently.The equivalent nodal point will shift would sub-apertures.The spot size variation due to sub-apertures image displacement was analyzed in detail.The effect of sub-aperture tilt and shift on image quality in stitching system was simplified with equivalent nodal point concept.Through application in structure design and tolerance analysis of sub-aperture stitching prototype,the tilt tolerance and displacement tolerance is 4 μrad and 6 μm respectively.Consequently the alignment tolerance was controlled effectly in stiching prototype.