Flat field before/after RGB2gray? Noise Reduction. Which is bettter?

I desire to remove the noise present in my image.

My original image is RGB image and the image processing for my project is done on grayscale image.

I found the either of following ways give different result.

RGB -> imflatfield (image, 20) -> RGB2gray.

RGB -> RGB2Gray() -> imflatfield(grayImage, 20)

What is the best method to remove the noise.

Answer 1

[Etsuo Maeda]

In imflatfield.m, RGB image input is converted from RGB to HSV. And only HSV value is used for flat-field correction. You can confirm this sequence using edit command. I am not sure which is better way, giving gray scaled image or giving HSV value. But it is possible to see the difference of those images.

A = imread('printedtext.png');
ihsv = rgb2hsv(A);
ihsv = ihsv(:, :, 3);
igray = rgb2gray(A);
montage({ihsv, igray})

HTH