8th Activity: Applications of Morphological Operations1 of 3: Preprocessing Text

A scanned document was given to us as shown in Figure 1. Using the different morphological operations learned previously, handwritten texts will be extracted. 

Figure 1. Scanned document

     A part of the scanned document was scanned. Since the image was slightly tilted, it was corrected using GIMP. This correction is necessary for further steps to be done. The cropped image was converted to grayscale. These are shown Figure 2. 

 Figure 2. Cropped image and its grayscale format

     To remove the horizontal lines, a filter was applied. The Fourier transform of the image was first obtained. The filter was done by blocking the high frequencies in the Fourier transform.The FT of the image was then multiplied to the filter. Figure 3 shows the Fourier transform and the filter that was made (using GIMP).

Figure 3. Fourier transform of the cropped image and the filter used

    The resulting image is shown in Figure 4. It can be seen that the horizontal lines are now removed. However, the lines that intersected with the letters were also removed. Thus, the letters seems to be cut into half. :( Figure 5 shows the binarized image.

Figure 4. The resulting filtered image

   

Figure 5. Binarized image

     Dilation was applied to the image where the structuring element is a diagonal. I chose a diagonal as a structuring element to connect the letters since the handwriting is somewhat diagonally written. :) Figure 6 shows the resulting dilation.

Figure 6. Dilated image

     Since the image has become thicker, skel  was utilized to make it thinner. Figure 7 shows the resulting image.

Figure 7. Skeletonized(thinned) image

     It can be seen that some of the letter can be easily read now. :)


Reference:

[1] . Maricor Soriano, "A8 - Applications of Morphological Operations 1 of 3: Preprocessing Text", Applied Physics 186 Manual, 2012


Self-evaluation:
I admit I submitted this later due to SPP and my own research and experiments, but I would still give myself a 10. I was able to produce the necessary output and I was able to use concepts learned from previous activities.