Converting An Array of Byte[] To A Bitmap

Question

I have a collection of Bitmaps that are stored in a List<byte[]> object. I want to combine all those Bitmaps into one image (kinda like a paneramic) without converting them back to bitmaps. I've tried using a MemoryStream (see below) but it doesn't seem to work. I always run out of memory or the image comes out corrupted. I would appreciate any thoughts/advice on the matter.

List<byte[]> FrameList = new List<byte[]>();

using (MemoryStream ms = new MemoryStream())
{
    for (int i = 0; i < FrameList.Count; i++)
    {
        //Does not work
        ms.Write(FrameList[i], i * FrameList[i].Length, FrameList[i].Length);
        //Does not work
        ms.Write(FrameList[i], 0, FrameList[i].Length); 
    }
    Bitmap img = (Bitmap)Bitmap.FromStream(ms);
    img.Save("D:\\testing.jpg", System.Drawing.Imaging.ImageFormat.Jpeg);
 }

To combine jpg's you need to decode them, stitch them and encode it back to jpg — Jeroen van Langen
– Jeroen van Langen, Commented Sep 9, 2021 at 14:36
Image manipulation doesn't work like that. No structured data manipulation works like that. What you want is not possible without at least some understanding of the data format, so the condition "without converting them back to bitmaps" is not realistically possible. — Agent_L
– Agent_L, Commented Sep 9, 2021 at 14:38
You can't just add the bytes together and make a large image, there's more to that than just the raw pixel data, like headers and colour details. — DavidG
– DavidG, Commented Sep 9, 2021 at 14:38
Appending the bytes of one image to the end of another is like trying to make one of these from one of these by doing this. — ProgrammingLlama
– ProgrammingLlama, Commented Sep 9, 2021 at 14:57

Martin Staufcik · Accepted Answer · 2021-09-09 14:39:31Z

1

The steps:

calculate the final image size as sum of size of the individual images
create a Bitmap with the final size
get the Graphics object
draw all images using the Graphics object

save the final Bitmap

var final = new Bitmap(width, height); // calculated final size
using (var graphics = Graphics.FromImage(final))
{
    graphics.DrawImage(...); // draw all partial images onto the final bitmap
}

edited Sep 9, 2021 at 14:39

answered Sep 9, 2021 at 14:36

Martin Staufcik

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1 Comment

Agent_L Over a year ago

The requirement is "without converting them back to bitmaps." and one can't know the width and height with raw bytes.

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