IronOCR How-Tos Streams How to Read from Streams Chaknith Bin Updated:July 28, 2025 Stream data refers to a continuous flow of binary information that can be read from or written to. In the context of programming and data handling, streams are used to efficiently process data that may be too large to fit entirely in memory. Streams allow data to be read or written in smaller, manageable chunks. IronOcr's import methods also accept data streams of images to be imported and read. This can be done by simply passing the stream data into one of the import methods. The method will handle all the necessary steps to import the image. Get started with IronOCR Start using IronOCR in your project today with a free trial. First Step: Start for Free How to Read from Streams Download a C# library for reading from streams Obtain and prepare the image stream data Pass the image stream to the OcrImageInput constructor to import the image Use the Read method to perform OCR Define the reading area by specifying the crop region Read Streams Example First, instantiate the IronTesseract class to perform OCR. Use the FromFile method of AnyBitmap to import the image file. This AnyBitmap object will be able to convert the image data into a stream. Next, use the using statement to create the OcrImageInput object by passing the image stream with the GetStream method of the AnyBitmap object. Finally, use the Read method to perform OCR. :path=/static-assets/ocr/content-code-examples/how-to/input-streams-read-streams.cs using IronOcr; using IronSoftware.Drawing; // Instantiate IronTesseract IronTesseract ocrTesseract = new IronTesseract(); // Read image file to AnyBitmap AnyBitmap anyBitmap = AnyBitmap.FromFile("Potter.tiff"); // Import image stream using var imageInput = new OcrImageInput(anyBitmap.GetStream()); // Perform OCR OcrResult ocrResult = ocrTesseract.Read(imageInput); Imports IronOcr Imports IronSoftware.Drawing ' Instantiate IronTesseract Private ocrTesseract As New IronTesseract() ' Read image file to AnyBitmap Private anyBitmap As AnyBitmap = AnyBitmap.FromFile("Potter.tiff") ' Import image stream Private imageInput = New OcrImageInput(anyBitmap.GetStream()) ' Perform OCR Private ocrResult As OcrResult = ocrTesseract.Read(imageInput) $vbLabelText $csharpLabel Specify Scan Region To improve performance on large images and obtain specific readings from certain regions, you can utilize the CropRectangle class. The OcrImageInput constructor accepts a CropRectangle object as a second parameter. This allows you to specify which region of the image document should be read. In the code example below, I specify that only the chapter number and title region should be read. :path=/static-assets/ocr/content-code-examples/how-to/input-streams-read-specific-region.cs using IronOcr; using IronSoftware.Drawing; using System; // Instantiate IronTesseract IronTesseract ocrTesseract = new IronTesseract(); // Read image file to AnyBitmap AnyBitmap anyBitmap = AnyBitmap.FromFile("Potter.tiff"); // Specify crop region Rectangle scanRegion = new Rectangle(800, 200, 900, 400); // Add image using var imageInput = new OcrImageInput(anyBitmap.GetStream(), ContentArea: scanRegion); // Perform OCR OcrResult ocrResult = ocrTesseract.Read(imageInput); // Output the result to console Console.WriteLine(ocrResult.Text); Imports IronOcr Imports IronSoftware.Drawing Imports System ' Instantiate IronTesseract Private ocrTesseract As New IronTesseract() ' Read image file to AnyBitmap Private anyBitmap As AnyBitmap = AnyBitmap.FromFile("Potter.tiff") ' Specify crop region Private scanRegion As New Rectangle(800, 200, 900, 400) ' Add image Private imageInput = New OcrImageInput(anyBitmap.GetStream(), ContentArea:= scanRegion) ' Perform OCR Private ocrResult As OcrResult = ocrTesseract.Read(imageInput) ' Output the result to console Console.WriteLine(ocrResult.Text) $vbLabelText $csharpLabel OCR Result Frequently Asked Questions How can I read image streams for OCR processing in .NET C#? In .NET C#, you can utilize IronOCR's import methods to read image streams by passing the stream data into the OcrImageInput constructor. This method efficiently handles the image data for OCR processing. What is the benefit of using streams for OCR in IronOCR? Using streams allows IronOCR to process large image files efficiently by handling data in smaller, manageable chunks. This approach optimizes memory usage and speeds up the OCR process. How do I specify a region of an image to read for OCR in C#? To specify a region of an image for OCR using IronOCR, you can use the CropRectangle class. Pass this as a parameter to the OcrImageInput constructor to focus on a specific area of the image. Can IronOCR handle real-time image stream OCR? Yes, IronOCR can handle real-time image stream OCR by continuously processing image data streams as they are received. This feature is beneficial for applications requiring immediate text recognition. How can I improve OCR performance on large images? To improve OCR performance on large images using IronOCR, specify a scan region with the CropRectangle class to limit processing to relevant areas, reducing the amount of data that needs to be analyzed. What is the role of the OcrImageInput constructor in IronOCR? The OcrImageInput constructor in IronOCR is used to import image streams and optionally define a specific region of interest for OCR processing. It streamlines the process of preparing images for text extraction. How does the Read method function in IronOCR? The Read method in IronOCR executes the optical character recognition process on the provided image stream. It extracts text from the image data and returns the recognized characters. Chaknith Bin Chat with engineering team now Software Engineer Chaknith works on IronXL and IronBarcode. He has deep expertise in C# and .NET, helping improve the software and support customers. His insights from user interactions contribute to better products, documentation, and overall experience. Reviewed by Jeffrey T. Fritz Principal Program Manager - .NET Community Team Jeff is also a Principal Program Manager for the .NET and Visual Studio teams. He is the executive producer of the .NET Conf virtual conference series and hosts 'Fritz and Friends' a live stream for developers that airs twice weekly where he talks tech and writes code together with viewers. Jeff writes workshops, presentations, and plans content for the largest Microsoft developer events including Microsoft Build, Microsoft Ignite, .NET Conf, and the Microsoft MVP Summit Ready to Get Started? Free NuGet Download Total downloads: 4,306,473 View Licenses