Question

我有一段使用OCR功能调用Microsoft Cognitive Services Vision API的代码。当我将特定图像传递给API调用时，它不会检测到任何单词。呼叫本身成功并返回200状态。当我通过Microsoft提供的演示UI屏幕使用相同的图像时，它可以工作并读取我期望的字符。

如果我转到此网址https://azure.microsoft.com/en-us/services/cognitive-services/computer-vision/并上传此图片

然后它起作用并返回201 19 4501。

当我尝试对同一图像使用以下代码时，它返回并不返回任何字符。

这是代码。下面的ScaleImageIfNeeded方法没有做任何事情，因为图像已经缩放到正确的大小（它只返回在字节数组中传递的相同）。

public async Task<string> ProcessImage(byte[] imageData)
        {
            var client = new HttpClient();

            client.DefaultRequestHeaders.Add("Ocp-Apim-Subscription-Key", ConnectionString);
            const string requestParameters = "language=unk&detectOrientation=true";
            const string uri = "https://eastus2.api.cognitive.microsoft.com/vision/v1.0/ocr?" + requestParameters;

            var byteData = ScaleImageIfNeeded(imageData);

            using (var content = new ByteArrayContent(byteData))
            {
                content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream");
                var response = await client.PostAsync(uri, content);

                var results = await response.Content.ReadAsStringAsync();

                return results;
            }
        }

JSON结果是这个

{"language":"unk","orientation":"NotDetected","regions":[]}

我完成了一整套与此相似的图像，我可以成功准备好大约一半的图像。另一半不会像这样返回任何内容。

正如下面的答案所示，我创建了一个.NET Framework 4.5.2控制台应用程序并尝试使用它上传图像，但结果相同。

internal class Program
    {
        private const string SubscriptionKey = "XXXXXXXXXX";
        //private const string UriBase = "https://westcentralus.api.cognitive.microsoft.com/vision/v1.0/ocr";
        private const string UriBase = "https://eastus2.api.cognitive.microsoft.com/vision/v1.0/ocr";

        private static void Main()
        {
            Console.WriteLine("Optical Character Recognition:");
            Console.Write("Enter the path to an image with text you wish to read: ");
            string imageFilePath = @"c:\temp\image.jpg";// Console.ReadLine();

            // Execute the REST API call.
            MakeOcrRequest(imageFilePath);

            Console.WriteLine("\nPlease wait a moment for the results to appear. Then, press Enter to exit...\n");
            Console.ReadLine();
        }

        private static async void MakeOcrRequest(string imageFilePath)
        {
            var client = new HttpClient();

            // Request headers.
            client.DefaultRequestHeaders.Add("Ocp-Apim-Subscription-Key", SubscriptionKey);

            // Request parameters.
            const string requestParameters = "language=unk&detectOrientation=true";

            // Assemble the URI for the REST API Call.
            const string uri = UriBase + "?" + requestParameters;

            // Request body. Posts a locally stored JPEG image.
            var byteData = GetImageAsByteArray(imageFilePath);

            using (var content = new ByteArrayContent(byteData))
            {
                // This example uses content type "application/octet-stream".
                // The other content types you can use are "application/json" and "multipart/form-data".
                content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream");

                // Execute the REST API call.
                var response = await client.PostAsync(uri, content);

                // Get the JSON response.
                string contentString = await response.Content.ReadAsStringAsync();

                // Display the JSON response.
                Console.WriteLine("\nResponse:\n");
                Console.WriteLine(JsonPrettyPrint(contentString));
            }
        }

        private static byte[] GetImageAsByteArray(string imageFilePath)
        {
            var fileStream = new FileStream(imageFilePath, FileMode.Open, FileAccess.Read);
            var binaryReader = new BinaryReader(fileStream);
            return binaryReader.ReadBytes((int)fileStream.Length);
        }

        private static string JsonPrettyPrint(string json)
        {
            if (string.IsNullOrEmpty(json))
                return string.Empty;

            json = json.Replace(Environment.NewLine, "").Replace("\t", "");

            var sb = new StringBuilder();
            var quote = false;
            var ignore = false;
            var offset = 0;
            const int indentLength = 3;

            foreach (var ch in json)
            {
                switch (ch)
                {
                    case '"':
                        if (!ignore) quote = !quote;
                        break;
                    case '\'':
                        if (quote) ignore = !ignore;
                        break;
                }

                if (quote)
                    sb.Append(ch);
                else
                {
                    switch (ch)
                    {
                        case '{':
                        case '[':
                            sb.Append(ch);
                            sb.Append(Environment.NewLine);
                            sb.Append(new string(' ', ++offset * indentLength));
                            break;
                        case '}':
                        case ']':
                            sb.Append(Environment.NewLine);
                            sb.Append(new string(' ', --offset * indentLength));
                            sb.Append(ch);
                            break;
                        case ',':
                            sb.Append(ch);
                            sb.Append(Environment.NewLine);
                            sb.Append(new string(' ', offset * indentLength));
                            break;
                        case ':':
                            sb.Append(ch);
                            sb.Append(' ');
                            break;
                        default:
                            if (ch != ' ') sb.Append(ch);
                            break;
                    }
                }
            }

            return sb.ToString().Trim();
        }

Answer 1

此示例适用于我的图像作为输入： https://docs.microsoft.com/en-us/azure/cognitive-services/computer-vision/quickstarts/csharp#optical-character-recognition-ocr-with-computer-vision-api-using-ca-nameocr-a

部分：使用C＃的计算机视觉API进行光学字符识别（OCR）。

Check out the screenshot for the result

Microsoft Cognitive Services Vision API会检测代码

1 个答案: