Kindly could you explain why you need to revert image?

[jeongc]

Hi
Somewhat I cannot understand why you need to revert.

#revert the image,and normalize it to 0-1 range
img = 1.0 - img/255.0

Regards

[adityag6994]

it gave me better results, although I don't know the correct reason!

[cah-icuro]

In short, it's because that's how the original images were formatted - with zero representing the background and nonzero values representing the more important digit pixels. Roughly speaking, this is to help guide the neural network towards the important parts of the image. For more details, see this explanation.