How to use the ocrd.model.OcrdPage.from_file function in ocrd

def process(self):
        """
        Performs the (text) recognition.
        """
        with tesserocr.PyTessBaseAPI(path=TESSDATA_PREFIX, lang=DEFAULT_MODEL) as tessapi:
            log.info("Using model %s in %s for recognition", tesserocr.get_languages()[0], tesserocr.get_languages()[1][-1])
            tessapi.SetPageSegMode(tesserocr.PSM.SINGLE_LINE)
            for (n, input_file) in enumerate(self.input_files):
                log.info("INPUT FILE %i / %s", n, input_file)
                self.workspace.download_file(input_file)
                page = OcrdPage.from_file(input_file)
                image_url = page.imageFileName
                log.info("page %s", page)
                for region in page.list_textregions():
                    textlines = region.list_textlines()
                    log.info("About to recognize text in %i lines of region '%s'", len(textlines), region.ID)
                    for (line_no, line) in enumerate(textlines):
                        log.debug("Recognizing text in region '%s' line '%s'", region.ID, line_no)
                        # TODO use binarized / gray
                        image = self.workspace.resolve_image_as_pil(image_url, line.coords)
                        tessapi.SetImage(image)
                        line.textequiv = tessapi.GetUTF8Text()
                self.add_output_file(
                    ID=mets_file_id(self.outputGrp, n),
                    input_file=input_file,
                    mimetype=MIMETYPE_PAGE,
                    content=page.to_xml()

def process(self):
        """
        Performs the region segmentation.
        """
        with tesserocr.PyTessBaseAPI(path=TESSDATA_PREFIX) as tessapi:
            for (n, input_file) in enumerate(self.input_files):
                page = OcrdPage.from_file(self.workspace.download_file(input_file))
                image = self.workspace.resolve_image_as_pil(page.imageFileName)
                log.debug("Detecting regions with tesseract")
                tessapi.SetImage(image)
                for component in tessapi.GetComponentImages(tesserocr.RIL.BLOCK, True):
                    box, index = component[1], component[2]
                    # the region reference in the reading order element
                    ID = "r%i" % index
                    page.add_reading_order_ref(ID, index)
                    page.add_textregion(ID, box)
                self.add_output_file(
                    ID=mets_file_id(self.outputGrp, n),
                    input_file=input_file,
                    mimetype=MIMETYPE_PAGE,
                    content=page.to_xml()
                )

def process(self):
        """
        Performs the line segmentation.
        """
        with tesserocr.PyTessBaseAPI(path=TESSDATA_PREFIX) as tessapi:
            for (n, input_file) in enumerate(self.input_files):
                page = OcrdPage.from_file(self.workspace.download_file(input_file))
                image_url = page.imageFileName
                for region in page.list_textregions():
                    log.debug("Detecting lines in %s with tesseract", region)
                    image = self.workspace.resolve_image_as_pil(image_url, region.coords)
                    tessapi.SetImage(image)
                    for component in tessapi.GetComponentImages(tesserocr.RIL.TEXTLINE, True):
                        region.add_textline(coords=component[1])
                self.add_output_file(
                    ID=mets_file_id(self.outputGrp, n),
                    input_file=input_file,
                    mimetype=MIMETYPE_PAGE,
                    content=page.to_xml()
                )