Convert EPUB to JPG in C#

JPG files can contain high-quality image data with lossless compression. This unique compression feature allows to quickly and efficiently share JPG images and use them widely on the Web, computers, and mobile devices. With Aspose.HTML for .NET, you can convert EPUB to JPG format programmatically with full control over a wide range of conversion parameters.

In this article, you find information on how to convert EPUB to JPG using ConvertEPUB() methods of the Converter class, and how to apply ImageSaveOptions and ICreateStreamProvider parameters.

Online EPUB Converter

You can convert EPUB to other formats with Aspose.HTML for .NET API in real time. First, load an EPUB file from your local drive and then run the example. The save options in the example are set by default. You will immediately receive the conversion result as a separate file.

If you want to convert EPUB to JPG programmatically, please see the following C# code examples.

EPUB to JPG by two lines of code

The static methods of the Converter class are primarily used as the easiest way to convert an EPUB file into various formats. You can convert EPUB to JPG in your C# application literally with two lines of code!

// Open an existing EPUB file for reading
using var stream = File.OpenRead(DataDir + "input.epub");

// Invoke the ConvertEPUB() method to convert EPUB to JPG
Converter.ConvertEPUB(stream, new ImageSaveOptions(ImageFormat.Jpeg), Path.Combine(OutputDir, "convert-by-two-lines.jpg"));

Convert EPUB to JPG

To convert EPUB to JPG, you should follow a few steps:

1. Open an existing EPUB file. In the example, we use the OpenRead() method of System.IO.FileStream class to open and read an EPUB file from the file system at the specified path.
2. Create a new ImageSaveOptions object with ImageFormat.Jpeg. By default, the Format property is PNG.
3. Use the ConvertEPUB() method of the Converter class to save EPUB as a JPG image. You need to pass the EPUB file stream, ImageSaveOptions, and output file path to the ConvertEPUB() method for EPUB to JPG conversion.

Please take a look over the following C# code snippet which shows the process of converting EPUB to JPG using Aspose.HTML for .NET.

// Open an existing EPUB file for reading
using var stream = File.OpenRead(DataDir + "input.epub");

// Prepare a path to save the converted file 
string savePath = Path.Combine(OutputDir, "input-output.jpg");            

// Create an instance of the ImageSaveOptions class 
var options = new ImageSaveOptions(ImageFormat.Jpeg);

// Call the ConvertEPUB() method to convert EPUB to JPG
Converter.ConvertEPUB(stream, options, savePath);

You can download the complete examples and data files from GitHub.

Save Options – ImageSaveOptions Class

Aspose.HTML for .NET allows converting EPUB to JPG using default or custom save options. ImageSaveOptions usage enables you to tune the rendering process. You can specify the image format, page size, margins, CSS media-type, etc.

Property	Description
Compression	Sets Tagged Image File Format (TIFF) Compression. By default, this property is LZW.
CSS	Gets a CssOptions object which is used for configuration of CSS properties processing.
Format	Sets the ImageFormat (JPG, PNG, BMP, TIFF, or GIF). By default, this property is PNG.
BackgroundColor	This property sets the color that will fill the background. By default, this property is Transparent.
PageSetup	This property gets a page setup object and uses it for configuration output page-set.
HorizontalResolution	Sets horizontal resolution for output images in pixels per inch. The default value is 300 dpi.
VerticalResolution	Sets vertical resolution for output images in pixels per inch. The default value is 300 dpi.
UseAntialiasing	This property sets the image rendering quality. Antialiasing is enabled by default.
Text	Gets a TextOptions object which is used for configuration of text rendering.

To learn more about the ImageSaveOptions class, please read the Fine-Tuning Converters article.

Convert EPUB to JPG using ImageSaveOptions

To convert EPUB to JPG with ImageSaveOptions specifying, you should follow a few steps:

1. Open an existing EPUB file.
2. Create a new ImageSaveOptions object with JPG ImageFormat and specify save options. By default, the Format property is PNG.
3. Use the ConvertEPUB() method of the Converter class to save EPUB as a JPG image. You need to pass the EPUB file stream, ImageSaveOptions, and output file path to the ConvertEPUB() method to convert EPUB to JPG.

The following C# code snippet shows how to convert EPUB to JPG using custom save options:

// Open an existing EPUB file for reading
using var stream = File.OpenRead(DataDir + "input.epub");

// Prepare a path to save the converted file 
string savePath = Path.Combine(OutputDir, "input-options.jpg");
            
// Initialize ImageSaveOptions 
var options = new ImageSaveOptions(ImageFormat.Jpeg)
{
    UseAntialiasing = true,
    HorizontalResolution = 400,
    VerticalResolution = 400,
    BackgroundColor = System.Drawing.Color.AliceBlue
};
options.PageSetup.AnyPage = new Page(new Aspose.Html.Drawing.Size(800, 500), new Margin(30, 20, 10, 10));

// Call the ConvertEPUB() method to convert EPUB to JPG
Converter.ConvertEPUB(stream, options, savePath);

The ImageSaveOptions() constructor initializes an instance of the ImageSaveOptions class that is passed to ConvertEPUB() method. The ConvertEPUB() method takes the stream, options, output file path savePath and performs the conversion operation.

In the above example, we use:

• BackgroundColor property that specifies the color that the background will be filled in. The default BackgroundColor is Transparent.
• HorizontalResolution and VerticalResolution properties that set horizontal/vertical resolution for output images in pixels per inch. By default, these properties are 300 dpi.
• UseAntialiasing property that sets the rendering quality for this image. This example uses UseAntialiasing = true for quality rendering.
• PageSetup property that specifies the page size and margins in pixels.

Use UseAntialiasing = true when you want to improve the visual quality of rendered shapes, text, and images in your application, especially when clarity and smooth edges are essential. Enabling antialiasing smooths out jagged edges by blending the colors of pixels around the edges, resulting in a softer, more refined look.

While UseAntialiasing = true provides better visual quality, it can also increase processing time. For applications where rendering speed is a priority, it may be optimal to set UseAntialiasing = false.

Output Stream Providers

If it is required to save files in the remote storage (e.g., cloud, database, etc.) you can implement the ICreateStreamProvider interface to have manual control over the file creating process. This interface is designed as a callback object to create a stream at the beginning of the document/page (depending on the output format) and release the early created stream after rendering the document/page.

Aspose.HTML for .NET provides various types of output formats for rendering operations. Some of these formats produce a single output file (for instance, PDF, XPS), others create multiple files (Image formats – JPG, PNG, etc.).

The example below shows how to implement and use your own MemoryStreamProvider in the application:

class MemoryStreamProvider : Aspose.Html.IO.ICreateStreamProvider
{
    // List of MemoryStream objects created during the document rendering
    public List<MemoryStream> Streams { get; } = new List<MemoryStream>();

    public Stream GetStream(string name, string extension)
    {
        // This method is called when only one output stream is required, for instance for XPS, PDF or TIFF formats
        MemoryStream result = new MemoryStream();
        Streams.Add(result);
        return result;
    }

    public Stream GetStream(string name, string extension, int page)
    {
        // This method is called when the creation of multiple output streams are required. For instance, during the rendering HTML to list of image files (JPG, PNG, etc.)
        MemoryStream result = new MemoryStream();
        Streams.Add(result);
        return result;
    }

    public void ReleaseStream(Stream stream)
    {
        // Here you can release the stream filled with data and, for instance, flush it to the hard-drive
    }

    public void Dispose()
    {
        // Releasing resources
        foreach (var stream in Streams)
            stream.Dispose();
    }
}

The following code snippet demonstrates how to convert an EPUB file to a JPG file using a memory stream.

// Open an existing EPUB file for reading
using var stream = File.OpenRead(DataDir + "input.epub");

// Create an instance of MemoryStreamProvider
using var streamProvider = new MemoryStreamProvider();

// Convert HTML to JPG using the MemoryStreamProvider
Converter.ConvertEPUB(stream, new ImageSaveOptions(ImageFormat.Jpeg), streamProvider);

// Get access to the memory streams that contain the resulted data
for (int i = 0; i < streamProvider.Streams.Count; i++)
{
    var memory = streamProvider.Streams[i];
    memory.Seek(0, System.IO.SeekOrigin.Begin);

    // Flush the page to the output file
    using (FileStream fs = File.Create(Path.Combine(OutputDir, $"input-page_{i + 1}.jpg")))
    {
        memory.CopyTo(fs);
    }
}

The ConvertEPUB(Stream, ImageSaveOptions, ICreateStreamProvider) method takes the conversion source, options, and instance of MemoryStreamProvider, which will be used to get an output stream, and performs the conversion operation.

Aspose.HTML offers a free online EPUB to JPG Converter that converts EPUB to JPG image with high quality, easy and fast. Just upload, convert your files and get results in a few seconds!