you said the topic yourself, image recognition. Any language can do it but for quick development id suggest MATLAB and for efficient programming id suggest C with recognition libraries (just google for one there are many out there). For the specifics of online poker if you are targetting a specific site just make a mask of their numbers and apply it to the location where the numbers are, the best match(which should be 100% if you are targetting a specific site) will be your corresponding number/suit. this is easy if you have a visual of what you are working with(i.e. a program that does screen captures and "clicks") but id suggest you ask in the hacking forums about getting the data from teh program itself rather than screen captures, although most websites ToS say you can't use a bot so make sure you aren't doing anything unethical!