to obtain uniform and zero average background intensity values

which process is to be performed to obtain uniform and zero average background intensity values for an image

Answer 1

[Image Analyst]

Thresholding? Or image segmentation? Can't really tell from your extraordinarily brief question.

[raj kumar]

for threshholding

[Image Analyst]

background = grayImage < someThreshold; % Detect dark background.
grayImage(background) = 0;  % Set those pixels to 0.