从.NET中的MS Access数据库读取OLE图像时出现ArgumentException [英] ArgumentException on reading an OLE image from an MS Access database in .NET

问题描述

我正在尝试从Access数据库读取图像.当我尝试使用Image.FromStream时，它读取字节，但给出未处理的System.ArgumentException.

I am trying to read an image from an Access database. It reads the bytes but it gives an unhandled System.ArgumentException when I try to use Image.FromStream.

这是我的代码:

 private Image ReadImageFromDB()
    {
        Image fetchedImg;
        if (rownumber >= 0)
        {
            byte[] fetchedimgbytes = (byte[])localDataTable.Rows[5]["Object"];
            MemoryStream stream = new MemoryStream(fetchedimgbytes);
           fetchedImg= Image.FromStream(stream);
            return fetchedImg;
        }
        else
        {
            MessageBox.Show("no image");
            return null;
        }
    }

推荐答案

我下载了示例文件，当我在Access中打开表时，[Img]列中的项目表示位图图像"，而不是长二进制数据" .

I downloaded your sample file and when I opened the table in Access the item in the [Img] column said "Bitmap Image", not "Long Binary Data".

因此，该行中的[Img]项目是"OLE包装"对象，而不是原始位图图像.如果提取该列的二进制内容(如在C#应用程序中所做的那样)，它将在原始二进制图像数据周围包含OLE包装，并且不是该格式中的有效位图图像.

Therefore the [Img] item in that row is an "OLE wrapped" object, not a raw bitmap image. If you extract the binary contents of that column (as you did from your C# application) it will include the OLE wrapper around the raw binary image data and will not be a valid bitmap image in that form.

您需要从二进制数据中删除OLE标头信息，然后才能将其识别为有效映像.有关如何执行此操作的信息，请参见以下问题:

You need to remove the OLE header information from the binary data before it will be recognized as a valid image. For information on how to do that see this question:

将访问图像OLE对象转换为C#中的原始图像字节数组

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