Blur method

Captcha 5

PNTSTR
5 years ago | edited 5 years ago

0

Hi everyone,
I tried a lot of ideas but can’t solve the level yet.
As for now I stuck at blur method. I can’t blur example.png image to get example_blur.png image. They are alike, but differ.
[s]REMOVED[/s]

11replies
6voices
177views
SIGKILL [r4v463]
5 years ago

0

Hi,
Please remove the last sentence that’s a spoil :p
I’ll PM you :)

? [bolofecal]
5 years ago

0

I think you are in right way. About spoilers I posted solution in solutions thread and this thread was public to all users lol

charter
5 years ago | edited 5 years ago

0

Well I solved the other captcha levels except this one. Difficult to write down my approaches here, because I don’t want to spoil things.

I’m thinking that I need to use some deconvolution algorithm. But the same as PNTSTR describes, you don’t know the used blur method and therefor you don’t know the PSF. Blind deconvolution could be an option but had no succes with it. I’m using python3 and opencv 3.x.x.

Can somebody give me a hint were to look?

PNTSTR
5 years ago

0

I have a hint for you.
Think about how this captcha generated on server side everytime. We know that this web-application write using PHP.
Before I finish this level I wrote the page, that can generate exactly the same captchas like here.

charter
5 years ago

0

Ok, thnx for the hint. I will have another look into it.

dimooz
5 years ago

0

[quote=PNTSTR]
We know that this web-application write using PHP.
[/quote]

Not sure everybody knows that, I thought people had to guess it?

@charter, if you could solve the previous captcha levels then I’m sure you’ll get this one very soon. Just don’t overthink it!

charter
5 years ago | edited 5 years ago

1

Solved it, I was using a wrong library which could do the same but didn’t got me exactly what I wanted. Thanks again people.

SIGKILL [r4v463]
5 years ago

0

Congrats :D

dimooz
5 years ago

0

Congrats'! Don’t forget to explain how you did in solution thread :)

charter
5 years ago | edited 5 years ago

0

[s]Sure will, busy with it as we speak.[/s] Done

Darwin [DIDIx13]
4 years ago

0

Hey dimooz, here is how we can tell HT is made in php (but we could guess it without doubt)

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