That'd be really hard to do though... you need a lot of pictures...
When I was searching to implement cap that I found botdetect which is open source but then you'd still need a lot of images (or tamper with all the images they give you).
The real problem is there really isn't anything a human can do online that you can't program a computer to do.
@Jackg
I mean we don't have to use very many images
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@TheQuin
I have a small idea like the one below but I don't know whether this can be applied or not
we can combine simple image and math
for example like this
we can ask the users who will claim the free rolls game to enter the results of the math operation from the last 1 digit of their balance according to the instructions in the captcha
example 1
instructions in captcha: "your last digit + 2"
then the correct answer for someone with a balance of 0.04497642 is "4"
example 2
instructions in captcha: "your last digit * four"
then the correct answer for someone with a balance of 0.04497642 is "8"
but someone who has a balance with the last digit "0" if he gets a mathematical operation "*" then the result will always be "0"
so maybe we should only use "+" and "-" in the captcha
with the last digit of the user balance I think it will make "a little" sure that the person who completes the captcha is the owner of the account (a bit similar to the checksum)
of course it won't last forever
they will definitely look for new ways to integrate
so we have to change the method in a certain period, for example 1 or 2 months
this will be a little like how Monero is fighting the ASIC device
but again I don't know if this is possible or not