A10 – Preprocessing Handwritten Text

I will try to obtain an enhanced handwriting in the scanned image that appears below.

Figure 1. Scanned Image

I will try to work on a part of this image shown in Figure 2.

Figure 2. Handwriting

To obtain the handwriting, I need to eliminate the lines present. First, I obtained the Fourier transform of the image, from here I can design a filter that can remove the horizontal lines present in the image.

im1 = imread("image.jpg");
f = im2gray(im1);
ft1 = fft2(f); // takes the ft of the image
ft2 = log(fftshift(abs(ft1))); // for smaller magnitude of ft
imshow(ft2, []);

Below is the Fourier transform of the image and the filter I used.

Figure 3. FT of handwriting

Figure 4. Filter

im1 = imread('image.jpg');
im2 = imread('filter.jpg');
fprint = im2gray(im1);
filter = im2gray(im2);
ft1 = fft2(fprint); // takes the ft of the image
FP = log(fftshift(abs(ft1))); // for smaller magnitude of ft
F = fftshift(filter);
FPF = ft1.*F; // convolve the images
final = ifft(FPF);
last = real(final);
imshow(last, [ ]);


I then obtained a treated image.

Figure 5

The next step is to convert this image to a binary image.

im1 = imread("last.jpg");
im2 = im2gray(im1);
im3 = abs(1-im2bw(im2, 0.56));
imshow(im3, []);

Figure 6. Binarized Image

To be able to read the image better, each letter in the hand writing should be one pixel thick. Dilation and erosion operator can do the trick. But this depends on the choice of structure element, which can enhance or destroy the letters. For this activity, I used a rectangular structure element with a dimension of 1x3.

im1 = imread("last.jpg");
im2 = im2gray(im1);
se1 = imread("structure.jpg");
se2 = im2gray(se1);
im3 = abs(1-im2bw(im2, 0.56));
se3 = im2bw(se2,0.5);
imwrite(im3, "last1.jpg");
e = erode(im3,se3,[2,2]);
imshow(e,[]);


The resulting image is:

Figure 7. Enhanced Image

Finally, I labeled each letter.

[L,n] = bwlabel(e); //labels each component
imshow(L+1, rand(n+1,3));

Separating the handwriting from the background was hard because the region of interest overlaps with the background. But in my opinion, Figures 6 and 7 are still readable and the letters can be separated hence the attempt to enhance the image was successful.

I rate myself 10/10 for this activity because I was able to do fast and without the help pf my classmates.