将字节转换为图像jpg

Question

i have a problem with convert byte[] to .jpg file. When I try to convert byte, I got a exception in this method:

using (MemoryStream ms = new MemoryStream(bytes, 0, bytes.Length))
{
   ms.Write(bytes, 0, bytes.Length);
   Image image = Image.FromStream(ms, true, false);
}

Exception:

The parameter is invalid in System.Drawing.Image.FromStream(Stream stream, Boolean useEmbeddedColorManagement, Boolean validateImageData)

Any suggestion?

Answer 1

Solution ^* : Remove the line: ms.Write(bytes, 0, bytes.Length);

_{* If this doesn't work, the bytes array doesn't contain valid image data.}

---

Reason:

This line initializes a MemoryStream with the bytes in a byte array. It will start the stream at position 0 (the beginning):

using (MemoryStream ms = new MemoryStream(bytes, 0, bytes.Length))

and in your case it can be simplified to:

using (MemoryStream ms = new MemoryStream(bytes))

This line then writes the same bytes into the stream. It will leave your stream at position bytes.Length (the end):

ms.Write(bytes, 0, bytes.Length);

This line will try to read an image from the stream starting at the current position (the end). Since 0 bytes don't make an image, it fails giving you the exception:

Image image = Image.FromStream(ms, true, false);

---

As noted by Jimi, it might be better wrapping this up into a method:

public static Image ImageFromByteArray(byte[] bytes)
{
    using (MemoryStream ms = new MemoryStream(bytes))
    using (Image image = Image.FromStream(ms, true, true))
    {
        return (Image)image.Clone();
    }
}

The reason for using Clone() is that it can cause trouble saving the image if the original stream has been disposed of.