Remove Noise from binary image.

I have to work on this image

When I convert this image into a binary image, I got noisy image like this:

Which pre-processing techniques should I need to apply on this? I need braille dots as white dots and remaining background black in binary image. Please help, I am a newbie.

[Jan]

An interesting problem. On the upper left of the image, I can recognize the dark shadows under the points only, and on the bottom I see the light on the upside of the point and shadow on the bottomside. Therefore I assume different techniques have to be combined. I had equivalent problems with a irregularily illuminated picture containing standard text and very curious about the answers.

[Anika Paulsen]

Try adaptive binarizing as documented here: https://www.mathworks.com/help/images/ref/imbinarize.html