Hi, I have a problem concerning MRI image normalization and scaling data between 0 and 1.

I have three tissue classes with different intensity range on a set of images (intensity range for each tissue is varying from image to image): for one image for instance I have: GM (100-150), L(0-150), WM(150-300). Now I want to normalize L to GM and WM, such that I can say how much brighter or darker L is relative to GM and WM. I was wondering how can I do it? and if I want to show the contrast of L, relative to GM and WM to be between 0 and 1, what will be the equation?

Thanks for your help in advance

## Image normalization and standardization

### Re: Image normalization and standardization

Hi,

I'm not quite sure if I fully understand the question: Do you know the intensity ranges for each picture and now want to tell how much darker or brighter L is?

In this case I suppose something like this is an approach:

ratio(l/GM) = (l - LL) * (LH - LL) / (GMH - GML)

ratio(l/WM) = (l - LL) * (LH - LL) / (WMH - WML)

where

l = Intensity of L in the region of interest

LH = High value of L range over whole image

LL = Low Value of L range over whole image

GMH = High value of GM range over whole image

GML = Low value of GM range over whole image

WMH = High value of GM range over whole image

WML = Low value of GM range over whole image

Just a guess, I'm not quite sure if I got your question correctly...

I'm not quite sure if I fully understand the question: Do you know the intensity ranges for each picture and now want to tell how much darker or brighter L is?

In this case I suppose something like this is an approach:

ratio(l/GM) = (l - LL) * (LH - LL) / (GMH - GML)

ratio(l/WM) = (l - LL) * (LH - LL) / (WMH - WML)

where

l = Intensity of L in the region of interest

LH = High value of L range over whole image

LL = Low Value of L range over whole image

GMH = High value of GM range over whole image

GML = Low value of GM range over whole image

WMH = High value of GM range over whole image

WML = Low value of GM range over whole image

Just a guess, I'm not quite sure if I got your question correctly...

Thomas Jetter

### Re: Image normalization and standardization

My goal is to compare intensity of ROI "L" on a series of images with each other, but each image has a different intensity range.

So I need to normalize intensity of each image first to something on that image, that at the end I be able to show the contrast: so here I have WM, and GM ROIs.

Now to show how much intensity of L brighter or darker is than WM and GM (on the same graph) for each image. So calculating each ratio separately does not help me.

I was thinking of making WM and GM 0 and 1 respectively, so I can show the status of L between this two classes. And I was thinking two point normalization may help me and an equation like this might be helpful,

New L = (Median intensity of "L" ROI - Median intensity of GM ROI) * (1/ (Median intensity of WM ROI -Median intensity of GM ROI))

But my scale didn't become 0 and 1, bust something between -1 and 1 almost.

I don't know which part I did wrong

So I need to normalize intensity of each image first to something on that image, that at the end I be able to show the contrast: so here I have WM, and GM ROIs.

Now to show how much intensity of L brighter or darker is than WM and GM (on the same graph) for each image. So calculating each ratio separately does not help me.

I was thinking of making WM and GM 0 and 1 respectively, so I can show the status of L between this two classes. And I was thinking two point normalization may help me and an equation like this might be helpful,

New L = (Median intensity of "L" ROI - Median intensity of GM ROI) * (1/ (Median intensity of WM ROI -Median intensity of GM ROI))

But my scale didn't become 0 and 1, bust something between -1 and 1 almost.

I don't know which part I did wrong