how to change pixel value after applying dwt on image?

hi. i want to change pixel value of an image after apply dwt on one of rgb channel like red channel but after applying dwt pixel value are negative and float and if use uint8 to bring values into [0 255] and chnging pixels and apply idwt and saving image as one of image format like png in extraction part some of pixel value has changed .how can i prevent it?

Answer 1

[Image Analyst]

You can either use mat2gray() to change the array values into the range 0-1 and then set the red channel, OR you can figure out what pixels need to be red and make up an image for the overlay and then tint those pixels red by using the overlay. Which do you want?

http://blogs.mathworks.com/steve/2009/02/18/image-overlay-using-transparency/

http://www.mathworks.com/matlabcentral/answers/104889-how-to-overlay-a-foreground-image-over-a-background-image