Cutting part of a PDF OK

Hello friends, I own a PDF file (payment slip with barcode), which may have more than one page. I need to cut a part of the first page only. I'm PHP programmer with great experience. I tried to convert to image and then cut the part you want and print. However, despite the naked eye look like the original and the new, the new printing did not allow a correct reading of the barcode. (In cell read correctly, but with the device itself to not read it.) Perhaps if there was the possibility of generating this part of the file, but without having to editalo would be ideal. important: I need to integrate my PHP application with the tool developed. I need to be able to run it from the command line, something like: "[login to view URL] [login to view URL] [login to view URL]" Make your offer, I'll spend the PDF file via chat so they can see if you can do the job.