[Insight-users] improve contrast and brightness

[Jayachandran, Ganesh]

Hi,

I am extracting a slice out of a MR volume as an unsigned short for feature extraction. The dynamic range of MR volume varies with different volumes. So I calculate the minimum and maximum pixel values of the MR volume and set the pixels values within the dynamic range using RescaleIntensityImageFilter. The problem I encounter here is that when the image is rescaled with complete range(0-65535) I see an image with low contrast, but when rescaled within the dynamic range I get a black image. The images were viewed after saving it in png format. Kindly let me know if this is the correct way to set the dynamic range.

With the low contrast image obtained after rescaling in full range, I calculate the histogram. Based on the histogram I would like to improve the contrast. I tried adaptive histogram equalization, but that does not give good results since there are some outliers that are having higher pixel values than other part of the image. How can I specify to equalize the pixels between certain limits say between 5% and 95% of the histogram. I am new to ITK. Any pointer to a probable solution would be of good help.

Regards,
Ganesh



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