CODEWITHSUNDEEP
c#
5ilverFox
5ilverFox

Reputation: 51

Converting Image to Bytes and back

I know there is a lot of help already about this subject, but using this help I ran into a problem: I have an image list with icons that I display in a tree view on a windows form and that works.

Now I want to take these icons, put them in a table, clear the image list and then load the image list from the table. This is to test if I can use a table to maintain the icons.

The problem is that the icons display a black background using this method. I use BytesFromImage to write to an Image column in the table and ImageFromStream and StreamFromBytes to read the data back to an image.

What am I missing? 

public static byte[] BytesFromImage(Image TheImage)
{
    MemoryStream ms = new MemoryStream();
    TheImage.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
    return ms.ToArray();
}

public static Stream StreamFromBytes(byte[] DataBytes)
{
    MemoryStream stream = new MemoryStream();
    stream.Write(DataBytes, 0, DataBytes.Length);
    stream.Seek(0, SeekOrigin.Begin);
    return stream;
}

public static Image ImageFromStream(Stream DataStream)
{
    return Bitmap.FromStream(DataStream);
}

Upvotes: 5

Views: 733

Answers (3)

5ilverFox
5ilverFox

Reputation: 51

I played around and changing the format to png solved the problem. Sorry for the unnecessary post.

Upvotes: 0

Lies
Lies

Reputation: 514

The black background is caused by converting the icons into the format GIF. Better use PNG, this should respect transparent backgrounds:

public static byte[] BytesFromImage(Image TheImage)
{
    MemoryStream ms = new MemoryStream();
    TheImage.Save(ms, System.Drawing.Imaging.ImageFormat.Png);
    return ms.ToArray();
}

Upvotes: 1

Formula12
Formula12

Reputation: 397

Actually there's nothing wrong with your code. The problem is format specification. I have run into this problem when i was trying to convert an image which I created from Photoshop with a format of PNG to JPEG/JPG. According to popular documentation like Microsoft, PNG images retain high detail of information of an image, JPG doesn't. JPEG is not good as a compression option when you want to compress images that have high transitional borders. Especially when porting from PNG to JPEG. You'll always notice that. I think the problem is that you are using a raw bitmap. Try parsing it to Image instead of Bitmap and see if this works

Image image = System.Drawing.Image.FromStream(stream);

Upvotes: 2

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