使用光学字符识别 (OCR) 进行手写内容检测
Vision API 可以检测并提取图片中的文本:
DOCUMENT_TEXT_DETECTION可提取图片(或文件)中的文本;其响应针对密集文本和文档进行了优化。JSON 包含页面、文本块、段落、字词和换行信息。
DOCUMENT_TEXT_DETECTION 的一项特定用途是检测图片中的手写内容。

亲自尝试
如果您是 Google Cloud 新手,请创建一个账号来评估 Cloud Vision API 在实际场景中的表现。新客户还可获享 $300 赠金,用于运行、测试和部署工作负载。
免费试用 Cloud Vision API文档文本检测请求
设置您的 Google Cloud 项目和身份验证
如果您尚未创建 Google Cloud 项目,请立即创建。展开本部分可查看相关说明。
- Sign in to your Google Cloud account. If you're new to Google Cloud, create an account to evaluate how our products perform in real-world scenarios. New customers also get $300 in free credits to run, test, and deploy workloads.
-
In the Google Cloud console, on the project selector page, select or create a Google Cloud project.
Roles required to select or create a project
- Select a project: Selecting a project doesn't require a specific IAM role—you can select any project that you've been granted a role on.
-
Create a project: To create a project, you need the Project Creator role
(
roles/resourcemanager.projectCreator), which contains theresourcemanager.projects.createpermission. Learn how to grant roles.
-
Verify that billing is enabled for your Google Cloud project.
-
Enable the Vision API.
Roles required to enable APIs
To enable APIs, you need the Service Usage Admin IAM role (
roles/serviceusage.serviceUsageAdmin), which contains theserviceusage.services.enablepermission. Learn how to grant roles. -
Install the Google Cloud CLI.
-
如果您使用的是外部身份提供方 (IdP),则必须先使用联合身份登录 gcloud CLI。
-
如需初始化 gcloud CLI,请运行以下命令:
gcloud init -
In the Google Cloud console, on the project selector page, select or create a Google Cloud project.
Roles required to select or create a project
- Select a project: Selecting a project doesn't require a specific IAM role—you can select any project that you've been granted a role on.
-
Create a project: To create a project, you need the Project Creator role
(
roles/resourcemanager.projectCreator), which contains theresourcemanager.projects.createpermission. Learn how to grant roles.
-
Verify that billing is enabled for your Google Cloud project.
-
Enable the Vision API.
Roles required to enable APIs
To enable APIs, you need the Service Usage Admin IAM role (
roles/serviceusage.serviceUsageAdmin), which contains theserviceusage.services.enablepermission. Learn how to grant roles. -
Install the Google Cloud CLI.
-
如果您使用的是外部身份提供方 (IdP),则必须先使用联合身份登录 gcloud CLI。
-
如需初始化 gcloud CLI,请运行以下命令:
gcloud init - BASE64_ENCODED_IMAGE:二进制图片数据的 base64 表示(ASCII 字符串)。此字符串应类似于以下字符串:
/9j/4QAYRXhpZgAA...9tAVx/zDQDlGxn//2Q==
- PROJECT_ID:您的 Google Cloud 项目 ID。
检测本地图片中的文档文本
您可以使用 Vision API 对本地图片文件执行特征检测。
对于 REST 请求,请将图片文件的内容作为 base64 编码的字符串在请求正文中发送。
对于 gcloud 和客户端库请求,请在请求中指定本地图片的路径。
REST
在使用任何请求数据之前,请先进行以下替换:
HTTP 方法和网址:
POST https://vision.googleapis.com/v1/images:annotate
请求 JSON 正文:
{
"requests": [
{
"image": {
"content": "BASE64_ENCODED_IMAGE"
},
"features": [
{
"type": "DOCUMENT_TEXT_DETECTION"
}
]
}
]
}
如需发送请求,请选择以下方式之一:
curl
将请求正文保存在名为 request.json 的文件中,然后执行以下命令:
curl -X POST \
-H "Authorization: Bearer $(gcloud auth print-access-token)" \
-H "x-goog-user-project: PROJECT_ID" \
-H "Content-Type: application/json; charset=utf-8" \
-d @request.json \
"https://vision.googleapis.com/v1/images:annotate"
PowerShell
将请求正文保存在名为 request.json 的文件中,然后执行以下命令:
$cred = gcloud auth print-access-token
$headers = @{ "Authorization" = "Bearer $cred"; "x-goog-user-project" = "PROJECT_ID" }
Invoke-WebRequest `
-Method POST `
-Headers $headers `
-ContentType: "application/json; charset=utf-8" `
-InFile request.json `
-Uri "https://vision.googleapis.com/v1/images:annotate" | Select-Object -Expand Content
如果请求成功,服务器将返回一个 200 OK HTTP 状态代码以及 JSON 格式的响应。
响应
{
"responses": [
{
"textAnnotations": [
{
"locale": "en",
"description": "O Google Cloud Platform\n",
"boundingPoly": {
"vertices": [
{
"x": 14,
"y": 11
},
{
"x": 279,
"y": 11
},
{
"x": 279,
"y": 37
},
{
"x": 14,
"y": 37
}
]
}
},
],
"fullTextAnnotation": {
"pages": [
{
"property": {
"detectedLanguages": [
{
"languageCode": "en"
}
]
},
"width": 281,
"height": 44,
"blocks": [
{
"property": {
"detectedLanguages": [
{
"languageCode": "en"
}
]
},
"boundingBox": {
"vertices": [
{
"x": 14, "y": 11
},
{
"x": 279, "y": 11
},
{
"x": 279, "y": 37
},
{
"x": 14, "y": 37
}
]
},
"paragraphs": [
{
"property": {
"detectedLanguages": [
{
"languageCode": "en"
}
]
},
"boundingBox": {
"vertices": [
{
"x": 14, "y": 11
},
{
"x": 279, "y": 11
},
{
"x": 279, "y": 37
},
{
"x": 14, "y": 37
}
]
},
"words": [
{
"property": {
"detectedLanguages": [
{
"languageCode": "en"
}
]
},
"boundingBox": {
"vertices": [
{
"x": 14, "y": 11
},
{
"x": 23, "y": 11
},
{
"x": 23, "y": 37
},
{
"x": 14, "y": 37
}
]
},
"symbols": [
{
"property": {
"detectedLanguages": [
{
"languageCode": "en"
}
],
"detectedBreak": {
"type": "SPACE"
}
},
"boundingBox": {
"vertices": [
{
"x": 14, "y": 11
},
{
"x": 23, "y": 11
},
{
"x": 23, "y": 37
},
{
"x": 14, "y": 37
}
]
},
"text": "O"
}
]
},
]
}
],
"blockType": "TEXT"
}
]
}
],
"text": "Google Cloud Platform\n"
}
}
]
}
Go
试用此示例之前,请按照《Vision 快速入门:使用客户端库》中的 Go 设置说明进行操作。 如需了解详情,请参阅 Vision Go API 参考文档。
如需向 Vision 进行身份验证,请设置应用默认凭证。如需了解详情,请参阅为本地开发环境设置身份验证。
// detectDocumentText gets the full document text from the Vision API for an image at the given file path.
func detectDocumentText(w io.Writer, file string) error {
ctx := context.Background()
client, err := vision.NewImageAnnotatorClient(ctx)
if err != nil {
return err
}
f, err := os.Open(file)
if err != nil {
return err
}
defer f.Close()
image, err := vision.NewImageFromReader(f)
if err != nil {
return err
}
annotation, err := client.DetectDocumentText(ctx, image, nil)
if err != nil {
return err
}
if annotation == nil {
fmt.Fprintln(w, "No text found.")
} else {
fmt.Fprintln(w, "Document Text:")
fmt.Fprintf(w, "%q\n", annotation.Text)
fmt.Fprintln(w, "Pages:")
for _, page := range annotation.Pages {
fmt.Fprintf(w, "\tConfidence: %f, Width: %d, Height: %d\n", page.Confidence, page.Width, page.Height)
fmt.Fprintln(w, "\tBlocks:")
for _, block := range page.Blocks {
fmt.Fprintf(w, "\t\tConfidence: %f, Block type: %v\n", block.Confidence, block.BlockType)
fmt.Fprintln(w, "\t\tParagraphs:")
for _, paragraph := range block.Paragraphs {
fmt.Fprintf(w, "\t\t\tConfidence: %f", paragraph.Confidence)
fmt.Fprintln(w, "\t\t\tWords:")
for _, word := range paragraph.Words {
symbols := make([]string, len(word.Symbols))
for i, s := range word.Symbols {
symbols[i] = s.Text
}
wordText := strings.Join(symbols, "")
fmt.Fprintf(w, "\t\t\t\tConfidence: %f, Symbols: %s\n", word.Confidence, wordText)
}
}
}
}
}
return nil
}
Java
在试用此示例之前,请按照Vision API 快速入门:使用客户端库中的 Java 设置说明进行操作。如需了解详情,请参阅 Vision API Java 参考文档。
public static void detectDocumentText(String filePath) throws IOException {
List<AnnotateImageRequest> requests = new ArrayList<>();
ByteString imgBytes = ByteString.readFrom(new FileInputStream(filePath));
Image img = Image.newBuilder().setContent(imgBytes).build();
Feature feat = Feature.newBuilder().setType(Type.DOCUMENT_TEXT_DETECTION).build();
AnnotateImageRequest request =
AnnotateImageRequest.newBuilder().addFeatures(feat).setImage(img).build();
requests.add(request);
// Initialize client that will be used to send requests. This client only needs to be created
// once, and can be reused for multiple requests. After completing all of your requests, call
// the "close" method on the client to safely clean up any remaining background resources.
try (ImageAnnotatorClient client = ImageAnnotatorClient.create()) {
BatchAnnotateImagesResponse response = client.batchAnnotateImages(requests);
List<AnnotateImageResponse> responses = response.getResponsesList();
client.close();
for (AnnotateImageResponse res : responses) {
if (res.hasError()) {
System.out.format("Error: %s%n", res.getError().getMessage());
return;
}
// For full list of available annotations, see http://g.co/cloud/vision/docs
TextAnnotation annotation = res.getFullTextAnnotation();
for (Page page : annotation.getPagesList()) {
String pageText = "";
for (Block block : page.getBlocksList()) {
String blockText = "";
for (Paragraph para : block.getParagraphsList()) {
String paraText = "";
for (Word word : para.getWordsList()) {
String wordText = "";
for (Symbol symbol : word.getSymbolsList()) {
wordText = wordText + symbol.getText();
System.out.format(
"Symbol text: %s (confidence: %f)%n",
symbol.getText(), symbol.getConfidence());
}
System.out.format(
"Word text: %s (confidence: %f)%n%n", wordText, word.getConfidence());
paraText = String.format("%s %s", paraText, wordText);
}
// Output Example using Paragraph:
System.out.println("%nParagraph: %n" + paraText);
System.out.format("Paragraph Confidence: %f%n", para.getConfidence());
blockText = blockText + paraText;
}
pageText = pageText + blockText;
}
}
System.out.println("%nComplete annotation:");
System.out.println(annotation.getText());
}
}
}Node.js
试用此示例之前,请按照《Vision 快速入门:使用客户端库》中的 Node.js 设置说明进行操作。 如需了解详情,请参阅 Vision Node.js API 参考文档。
如需向 Vision 进行身份验证,请设置应用默认凭证。如需了解详情,请参阅为本地开发环境设置身份验证。
// Imports the Google Cloud client library
const vision = require('@google-cloud/vision');
// Creates a client
const client = new vision.ImageAnnotatorClient();
/**
* TODO(developer): Uncomment the following line before running the sample.
*/
// const fileName = 'Local image file, e.g. /path/to/image.png';
// Read a local image as a text document
const [result] = await client.documentTextDetection(fileName);
const fullTextAnnotation = result.fullTextAnnotation;
console.log(`Full text: ${fullTextAnnotation.text}`);
fullTextAnnotation.pages.forEach(page => {
page.blocks.forEach(block => {
console.log(`Block confidence: ${block.confidence}`);
block.paragraphs.forEach(paragraph => {
console.log(`Paragraph confidence: ${paragraph.confidence}`);
paragraph.words.forEach(word => {
const wordText = word.symbols.map(s => s.text).join('');
console.log(`Word text: ${wordText}`);
console.log(`Word confidence: ${word.confidence}`);
word.symbols.forEach(symbol => {
console.log(`Symbol text: ${symbol.text}`);
console.log(`Symbol confidence: ${symbol.confidence}`);
});
});
});
});
});Python
试用此示例之前,请按照《Vision 快速入门:使用客户端库》中的 Python 设置说明进行操作。 如需了解详情,请参阅 Vision Python API 参考文档。
如需向 Vision 进行身份验证,请设置应用默认凭证。如需了解详情,请参阅为本地开发环境设置身份验证。
def detect_document(