intensity correction in images

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Turbulence Analysis
Turbulence Analysis el 31 de Mayo de 2021
Comentada: Turbulence Analysis el 24 de Jun. de 2021
Hi,
I intend to correct the intensity in the images which arises due to the non uniformity in the illumination source.
As illustrated in the attched image, due to presence of inhomogeneity associated with the illumination source, the intensity is maximum at left and right side, however it is low on top and bottom. Now I intend to have uniform intensity through out. Is there any way out to achieve this ??
I tried with the normalize option e.g., But I am not succesful ..
normalize ( image data, 'range')

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Image Analyst
Image Analyst el 31 de Mayo de 2021
If that is your illumination source, you need to convert that to a percentage image and then divide your test images by the percentage image.
maxValue = max(illuminationImage(:))
percentageImage = double(illuminationImage) / maxValue;
correctedImage = double(testImage) ./ percentageImage;
Rationale: If the image only has 90% as many photons hitting the scene there, you'd need to divide by 0.9 there to bring it up to the intensity it should have (the intensity it would have if it were illuminated by the full max intensity).
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Image Analyst
Image Analyst el 6 de Jun. de 2021
No. It would be something like
mask = grayImage > someThresholdValue;
maxValue = max(grayImage(:))
grayImage(mask) = maxValue; % Set everything in the ring equal to the max value.
Turbulence Analysis
Turbulence Analysis el 24 de Jun. de 2021
Appologies for being late in responding.. Yes, I am getting the desired results....

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Turbulence Analysis
Turbulence Analysis el 31 de Mayo de 2021
Many thanks..
I have tried, but didn't get the desired results.. I have attached the corrected image, which I have got
I have attached test image, illumination image mat files for your reference.
  5 comentarios
Amit
Amit el 5 de Jun. de 2021
You need to normalize intensity of all images and then you segmentation of region of intest will be become uniform.
Adjusting contrast of images so as to cover complete dynamic range of intensity of all pixels.
Please send all of your database images as zip file to amit.kenjale@gmail.com, I will try our some code that will work for all of your images.
Turbulence Analysis
Turbulence Analysis el 5 de Jun. de 2021
Amit,
Thanks for the suggestion. I have attched the .mat file of the sample image here... Please let me know if you get any issues while accessing...

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