How to decrypt this captcha?

Question

CAPTCHA

Good afternoon friends!
I set out to decipher the captcha
And here's how I do it:
1. Convert to binary form, reducing everything to 1 and 0 (grayscale yes, of course)
2. Remove photo
3. Divide by letters - this is where my problem begins. Now I run through the matrix and see if there are units in the column, if not, then I add a new letter to the array. This method would be good if there were no noise.
4. Further, using the PHP-ML library, I process all this and get the result.
The fact is that this captcha has noises and because of them several letters merge into one. For this image (rf6c) I get the result "rf". And this is not the only negative. To determine whether it's a letter or noise, I have to take the average number of units in the array and throw out everything that is less or more than this number.
Tell me by what methods can I remove the strokes on the image, or can there be other options to spell these images?

Answer 1

antigate, captchabot, deathbycaptcha, pixodrom, ripcaptcha... There are a lot of
services to bypass

Answer 2

Well, in general, you can use the function from the OpenCV library - findContours (), it will select connected groups of pixels, consisting of the same color (that is, you will have 4 pictures), then just create a regular convolutional neural network using Conv2d layers and determine what kind of letter or number on picture. To determine the numbers, there is a dataset mnist, when I did something similar, the accuracy of determining the number was 95%.
PS don't forget to convert the image to binary