how to make background white?

how to make background of gray scale image white?

Answer 1

[Image Analyst]

First segment your image into foreground and background, perhaps using some techniques from my File Exchange: http://www.mathworks.com/matlabcentral/fileexchange/?term=authorid%3A31862

So now you have a background mask binary image that defines the background. To set those pixels equal to the bright value allowed for that class of image use:

maxGrayLevel = intmax(class(grayImage))
grayImage(mask) = maxGrayLevel;

where grayImage is your gray scale image and mask is your logical binary background mask.