Remove background (ghost photo) from an image with characters?

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I am trying to do text extraction from some images, however, these come with a bit of background, I have tried to "play" with contrast and brightness, as well as looking to apply thresholding techniques like otsu.

Do you have any suggestions on how to improve the extraction? I leave below some parts of the processing, as well as the input and output, any recommendation will be welcome.

Input:
Input

Output:

output

Processing:

enhancer = ImageEnhance.Brightness(img)
img = enhancer.enhance(1.62)  # 1.8
enhancer2 = ImageEnhance.Contrast(img)
img = enhancer2.enhance(1.8)  # 2
img = np.array(img)
thresh = cv2.threshold(img, 0, 255, cv2.THRESH_BINARY | cv2.THRESH_OTSU)[1]
opencv image-processing python-imaging-library ocr python
1 Answers

You should perform adaptive threshold. The algorithm divides the image into blocks of pre-defined size. Every block is given a different threshold value based on the pixel intensities within that block. In the following example, threshold is obtained based on Gaussian weight applied to sum of all pixel values within each block (meaning similar pixel values are given more weightage based on Gaussian curve). Binarization is carried out based on this value for each block. Check this page for more

For the given image, I tried the following:

im = cv2.imread('text_block.jpg')
green_channel = im[:,:,1]
th = cv2.adaptiveThreshold(green_channel, 255, cv2.ADAPTIVE_THRESH_GAUSSIAN_C, cv2.THRESH_BINARY, 27, 6)

enter image description here

You will have to try tweaking the parameters to get a better result. And also try cv.ADAPTIVE_THRESH_MEAN_C

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