[[["容易理解","easyToUnderstand","thumb-up"],["確實解決了我的問題","solvedMyProblem","thumb-up"],["其他","otherUp","thumb-up"]],[["難以理解","hardToUnderstand","thumb-down"],["資訊或程式碼範例有誤","incorrectInformationOrSampleCode","thumb-down"],["缺少我需要的資訊/範例","missingTheInformationSamplesINeed","thumb-down"],["翻譯問題","translationIssue","thumb-down"],["其他","otherDown","thumb-down"]],["上次更新時間：2025-09-04 (世界標準時間)。"],[],[],null,["# Learn about character recognition features\n\nOptical Character Recognition (OCR) is one of the three Vertex AI\npre-trained APIs on Google Distributed Cloud (GDC) air-gapped appliance. The OCR\nservice detects text in [various file types](#supported-file-types), such as\nimages, document files, and handwritten text.\n\nOCR offers the following methods available in\nGDC air-gapped appliance to recognize text:\n\n| **Note:** The `BatchAnnotateImages` and `BatchAnnotateFiles` API methods only support a single request per batch call.\n\nLearn more about the [supported languages](/distributed-cloud/hosted/docs/latest/appliance/application/ao-user/vertex-ai-ocr-supported-langs)\ndetected by the text recognition feature.\n\nOptical character recognition features\n--------------------------------------\n\nThe OCR API can detect and extract text from images. The\nfollowing two annotation features support optical character recognition:\n\n- `TEXT_DETECTION` detects and extracts text from any image. For example, a\n photograph might contain a street or traffic sign. The OCR\n service returns a JSON file with the extracted string, individual words, and\n their bounding boxes.\n\n **Figure 1.** Road sign photograph where the OCR API detects\n words and their bounding boxes.\n- `DOCUMENT_TEXT_DETECTION` also extracts text from an image, but the service\n optimizes the response for dense text and documents. For example, a scanned\n image of typed text might contain several paragraphs and headings. The\n OCR service returns a JSON file with page, block, paragraph,\n word, and break information.\n\n **Figure 2.** Scanned image of typed text where the OCR API detects information such as words, pages, and paragraphs.\n\nHandwritten text\n----------------\n\nFigure 3 is an image of handwritten text. The OCR API detects and\nextracts text from these images. For a list of handwriting scripts that\nsupport handwriting recognition, see\n[Handwriting scripts](/distributed-cloud/hosted/docs/latest/appliance/application/ao-user/vertex-ai-ocr-supported-langs#handwriting-scripts).\n\n**Figure 3.** Handwriting image where the OCR API detects text.\n\nOptical character recognition limits\n------------------------------------\n\nYou can recognize up to 30 images per minute, equivalent to one image every two\nseconds per appliance unit.\n\nThe `BatchAnnotateImages` and `BatchAnnotateFiles` API methods only support a\nsingle request per batch call.\n\nThe following table lists the current limits of the OCR service\nin Distributed Cloud.\n\nSubmitted files for the OCR API that exceed the maximum number of\npages or the maximum file size return an error. Submitted files that exceed the\nmaximum image size are downsized to 20 million pixels.\n\nSupported file types for OCR\n----------------------------\n\nThe OCR pre-trained API detects and transcribes\ntext from the following file types:\n\n- PDF\n- TIFF\n- JPG\n- PNG\n\nYou must store the files locally in your Distributed Cloud environment. You\ncan't access files hosted in Cloud Storage or publicly available files for\ntext detection."]]
