图片格式未知

Question

我正在尝试使用 .Net Core 2.2 将图像读入 Base64 格式，但它抛出

ArgumentException: Image format is unknown. System.Drawing.Image.FromFile(string filename, bool useEmbeddedColorManagement)

文件路径正确，我已经双重和三次检查文件是否存在。

我尝试用大写和小写扩展名命名我的 PNG。

这不会在 windows 本地发生，但一旦应用程序部署到 linux 就会发生。有问题的代码如下。

    public static string ImageToBase64(string filePath)
    {
        System.Diagnostics.Debug.WriteLine($"File Path for Image: {filePath}");
        string base64String;
        using (var image = Image.FromFile(Path.GetFullPath(filePath)))
        {
            using (var ms = new MemoryStream())
            {
                image.Save(ms, image.RawFormat);
                image.Dispose();
                byte[] imageBytes = ms.ToArray();
                base64String = Convert.ToBase64String(imageBytes);
                imageBytes = null;
                ms.Dispose();
            }
        }
        GC.Collect();
        return base64String;
    }

编辑

我也试过使用带位图的文件流。

    public static string ImageToBase64(string filePath)
    {
        string base64String;
        using(var fs = new FileStream(filePath,FileMode.Open))
        using (var image = new Bitmap(fs))
        {
            using (var ms = new MemoryStream())
            {
                image.Save(ms, ImageFormat.Png);
                image.Dispose();
                byte[] imageBytes = ms.ToArray();
                base64String = Convert.ToBase64String(imageBytes);
                imageBytes = null;
                ms.Dispose();
            }
        }
        GC.Collect();
        return base64String;
    }

这将引发以下异常：

Exception thrown: 'System.ArgumentException' in System.Drawing.Common.dll: 'Image format is unknown.' Stack trace:

at System.Drawing.Image.InitializeFromStream(Stream stream) at System.Drawing.Bitmap..ctor(Stream stream)

Answer 1

我可以给你我用的扩展，希望对你有帮助：

public static string Image2Base64(string xPath)
{
    //PNG TO BASE64         
    byte[] bytes = File.ReadAllBytes(xPath); //READ BYTES
    if (bytes == null) return null;

    //CONVERT BASE64
    return Convert.ToBase64String(bytes);
}

如果您仍然遇到问题，那么您的 base64 字符串有问题。用这个验证一下：

(.png) =

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Answer 2

虽然我仍然不确定为什么 Image.FromFile 和使用位图不起作用，但我设法通过使用来自 SixLabors 的 ImageSharp 使其工作。

工作代码如下。

    public static string ImageToBase64(string filePath)
    {
        string base64String;
        using (var image = SixLabors.ImageSharp.Image.Load(filePath))
        {
            using (var ms = new MemoryStream())
            {
                image.Save(ms, new PngEncoder());
                image.Dispose();
                byte[] imageBytes = ms.ToArray();
                base64String = Convert.ToBase64String(imageBytes);
                imageBytes = null;
                ms.Dispose();
            }
        }
        GC.Collect();
        return base64String;
    }

Answer 3

我在尝试访问 64 字节的 png 文件时收到此错误消息。当我用 paint 将相同的文件保存为 32 位 png 时，问题就解决了。

图片格式未知

Image format Unknown

c#

syncfusion

.net-core