# tesseract > OCR (Optical Character Recognition) engine. - Recognize text in an image and save it to `output.txt` (the '.txt' extension is added automatically): `tesseract {{image.png}} {{output}}` - Specify a custom language (default is English) with an ISO 639-2 code (e.g. deu = Deutsch = German): `tesseract -l deu {{image.png}} {{output}}` - List the ISO 639-2 codes of available languages: `tesseract --list-langs` - Specify a custom page segmentation mode (default is 3): `tesseract -psm {{0_to_10}} {{image.png}} {{output}}` - List page segmentation modes and their descriptions: `tesseract --help-psm`