IronOCR How-Tos System.Drawing Objects How to Read from System.Drawing Objects Chaknith Bin Updated:July 28, 2025 System.Drawing.Bitmap is a class in the .NET Framework used for working with bitmap images. It provides methods and properties to create, manipulate, and display bitmap images. System.Drawing.Image is a base class for all GDI+ image objects in the .NET Framework. It is the parent class for various image types, including System.Drawing.Bitmap. IronSoftware.Drawing.AnyBitmap is a bitmap class in IronDrawing, an open-source library originally developed by Iron Software. It helps C# software engineers replace System.Drawing.Common in .NET projects on Windows, macOS, and Linux platforms. Get started with IronOCR Start using IronOCR in your project today with a free trial. First Step: Start for Free How to Read from System.Drawing Objects Download a C# library for reading System.Drawing Objects Obtain System.Drawing objects such as Bitmap and Image Construct the OcrImageInput class using the acquired data Utilize AnyBitmap from Iron Software for Linux and macOS Define the reading area by specifying the crop region Read System.Drawing.Bitmap Example First, instantiate the IronTesseract class to perform OCR. Create a System.Drawing.Bitmap from one of the various methods. In the code example, I've decided to use a file path. Next, use the using statement to create the OcrImageInput object, passing the image from the System.Drawing.Bitmap object to it. Finally, use the Read method to perform OCR. :path=/static-assets/ocr/content-code-examples/how-to/input-system-drawing-read-bitmap.cs using IronOcr; using System.Drawing; // Instantiate IronTesseract IronTesseract ocrTesseract = new IronTesseract(); // Read image file to Bitmap Bitmap bitmap = new Bitmap("Potter.tiff"); // Import System.Drawing.Bitmap using var imageInput = new OcrImageInput(bitmap); // Perform OCR OcrResult ocrResult = ocrTesseract.Read(imageInput); Imports IronOcr Imports System.Drawing ' Instantiate IronTesseract Private ocrTesseract As New IronTesseract() ' Read image file to Bitmap Private bitmap As New Bitmap("Potter.tiff") ' Import System.Drawing.Bitmap Private imageInput = New OcrImageInput(bitmap) ' Perform OCR Private ocrResult As OcrResult = ocrTesseract.Read(imageInput) $vbLabelText $csharpLabel Read System.Drawing.Image Example Reading from a System.Drawing.Image is as simple as creating the OcrImageInput object with the Image and then performing the standard OCR process using the Read method. :path=/static-assets/ocr/content-code-examples/how-to/input-system-drawing-read-image.cs using IronOcr; using Image = System.Drawing.Image; // Instantiate IronTesseract IronTesseract ocrTesseract = new IronTesseract(); // Open image file as Image Image image = Image.FromFile("Potter.tiff"); // Import System.Drawing.Image using var imageInput = new OcrImageInput(image); // Perform OCR OcrResult ocrResult = ocrTesseract.Read(imageInput); Imports IronOcr Imports Image = System.Drawing.Image ' Instantiate IronTesseract Private ocrTesseract As New IronTesseract() ' Open image file as Image Private image As Image = Image.FromFile("Potter.tiff") ' Import System.Drawing.Image Private imageInput = New OcrImageInput(image) ' Perform OCR Private ocrResult As OcrResult = ocrTesseract.Read(imageInput) $vbLabelText $csharpLabel Read IronSoftware.Drawing.AnyBitmap Example Similarly, after creating or obtaining an AnyBitmap object, you can construct the OcrImageInput class. The constructor will take care of all the necessary steps to import the data. The code example below demonstrates this. :path=/static-assets/ocr/content-code-examples/how-to/input-system-drawing-read-anybitmap.cs using IronOcr; using IronSoftware.Drawing; // Instantiate IronTesseract IronTesseract ocrTesseract = new IronTesseract(); // Open image file as AnyBitmap AnyBitmap anyBitmap = AnyBitmap.FromFile("Potter.tiff"); // Import IronSoftware.Drawing.AnyBitmap using var imageInput = new OcrImageInput(anyBitmap); // Perform OCR OcrResult ocrResult = ocrTesseract.Read(imageInput); Imports IronOcr Imports IronSoftware.Drawing ' Instantiate IronTesseract Private ocrTesseract As New IronTesseract() ' Open image file as AnyBitmap Private anyBitmap As AnyBitmap = AnyBitmap.FromFile("Potter.tiff") ' Import IronSoftware.Drawing.AnyBitmap Private imageInput = New OcrImageInput(anyBitmap) ' Perform OCR Private ocrResult As OcrResult = ocrTesseract.Read(imageInput) $vbLabelText $csharpLabel Specify Scan Region In the construction of the OcrImageInput class, you can specify the area to scan. This allows you to define the specific region of the image document for OCR. Depending on the image document, specifying the scanning region can significantly enhance performance. In the provided code example, I specify that only the chapter number and title should be extracted. :path=/static-assets/ocr/content-code-examples/how-to/input-images-read-specific-region.cs using IronOcr; using IronSoftware.Drawing; using System; // Instantiate IronTesseract IronTesseract ocrTesseract = new IronTesseract(); // Specify crop region Rectangle scanRegion = new Rectangle(800, 200, 900, 400); // Add image using var imageInput = new OcrImageInput("Potter.tiff", 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() ' Specify crop region Private scanRegion As New Rectangle(800, 200, 900, 400) ' Add image Private imageInput = New OcrImageInput("Potter.tiff", 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 What is System.Drawing.Bitmap? System.Drawing.Bitmap is a class in the .NET Framework used for working with bitmap images. It provides methods and properties to create, manipulate, and display bitmap images. What is the role of System.Drawing.Image in .NET? System.Drawing.Image is a base class for all GDI+ image objects in the .NET Framework, serving as the parent class for various image types, including System.Drawing.Bitmap. How can I perform OCR on a bitmap image? You can perform OCR on a System.Drawing.Bitmap by using a library like IronOCR, where you create an OcrImageInput object with the bitmap and then use the Read method to extract text. How does a custom bitmap class help in .NET projects? IronSoftware.Drawing.AnyBitmap, a bitmap class in the IronDrawing library, helps C# software engineers replace System.Drawing.Common in .NET projects on Windows, macOS, and Linux platforms. How do you specify a scan region for OCR in an image processing library? In IronOCR, you can specify a scan region by defining the area to scan using coordinates and dimensions in the OcrImageInput class, which can enhance performance by focusing on specific areas of the image. How do you read a System.Drawing.Image using an OCR library? To read a System.Drawing.Image using IronOCR, create an OcrImageInput object with the image and perform the standard OCR process using the Read method. What is the use of an OCR engine in image text extraction? IronTesseract is used to initialize the Tesseract OCR engine in IronOCR, allowing developers to perform OCR operations on images. Can an OCR library be used on Linux and macOS? Yes, IronOCR can be used on Linux and macOS by utilizing AnyBitmap from Iron Software, which supports these platforms. What is the advantage of defining a specific scan region in an image? Defining a specific scan region allows you to focus on a particular area of an image for OCR, which can improve performance and accuracy by narrowing the scan to relevant sections. 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. 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