Secondly,detected all of the feature points on each scan lines in the image utilizing the method of finding local gray minimum points,and then abandoned the false feature points and got a fixed length iris code.

That is linearly changing the coefficients of the grey level and the driving current according to the maximum grey level of a frame,to achieve the contrast enhancement between the blac.

To reduce the complexity in calculating the input similarity matrix of the affinity propagation clustering,it was proposed that all grey levels were selected to be used as data points instead of all pixels in the image.

This algorithm solves the problem of IR image details reduce and the loss of gray level while using algorithm of gray threshold segmentation and eliminates the random noise and background noise around the IR object successfully,achieves a remarkable effect of the denoising.

A method is presented to calculate automatically the best gray threshold,which is suitable for images under different scanning resolutions.

The key content of the algorithm is the interpolation of the position coordinate and the interpolation of grey scale.

Gray scale of DNA sample strip on electrophoresis picture were analyzed by Image J software.