Re: Leveling Image

Posted by Gabriel Landini on Aug 22, 2011; 10:19am
URL: http://imagej.273.s1.nabble.com/Leveling-Image-tp3683357p3683361.html

On Monday 22 Aug 2011, you wrote:
> I would really appreciate if someone could guide me that what is the best
> method to bring the whole image to the same level. Its like I have images
> in which Small surface corrugations can sometimes be dominated by the
> noise in the scanner system. Typically, this creates observable steps
> between subsequent scan lines. Likewise, temporary contamination of the
> probe will cause the scan lines to be leveled differently. How can I bring
> the scan lines to more probable level.

It is nearly impossible to give useful advice without seeing what your images
look like.
I imagine that if the images have areas of "background" that appear in all
scan lines, and the background is expected to appear constant, you could
identify which pixels in each scan line are the background (or part of it) to
get their mean to offset the grey values of the whole line so the background
pixels all have the same mean.
But maybe this is not enough as there might be a multiplicative effect, in
which case you need to do something more than adding/subtracting an offset.

Most importantly you need a better method of image capture or get the scanner
serviced. Post processing can only do certain things. If the change of
intensity is random (and constant for each line), then you could increase the
scanning speed and capture more images, then integrate/average them in the
hope that the random variations average out over several shots (this noise
suppression factor would be about the sqrt(images) ). But perhaps the
artifacts you get change the intensity as the line is scanned, which would
make the whole thing much more complicated.

Cheers

Gabriel