create bitmap with filestream

I need to create a bitmap with a filestream. So far I have this Code:

 using (Fi开发者_JAVA百科leStream bmp = File.Create(@"C:\test.bmp"))
        {
            BinaryWriter writer = new BinaryWriter(bmp);
            int i = 0;

          //  writer.Write((char*)&fileheader, sizeof(fileheader));
          //  writer.Write((char*)&infoheader, sizeof(infoheader));

            for (int rows = 0; rows < 160; rows++)
            {
                for (int cols = 0; cols < 112; cols++)
                {
                    writer.Write(CamData[i]);
                    i++;
                }
            }

            bmp.Close();
        }

but I still need the header Informations for the bitmap. My Problem is, that I dont know how to implement they in C#. I know the resolution (320 x 240 ) and my pixeldata are 16 bit grayscale values given in a ushort array.

thanks

There is a constructor to create a Bitmap from a byte array. Then, save it to stream in bmp format, using Bitmap's member functions. See here and here.

Seems the System.Drawing classes don't like handling 16 bit grayscale, probably because the underlying GDI+ object sees its colour components as values from 0 to 255, whereas 16 bit grayscale actually means you can have 65535 shades of gray.

This means you have two options: either you switch to PresentationCore, and create your image with that, or you downsample the values to byte size and make an 8-bit grayscale image.

The first option is explained in this answer.

The second option includes three steps:

• Downsample the data to 1 byte per pixel
• Generate a grayscale colour palette (since 8-bit grayscale is technically paletted)
• Create an 8-bit indexed image out of your downsampled data and the palette.

The code:

Byte[] camDataBytes = new Byte[CamData.Length];
for(Int32 i = 0; i < camData.Length; i++)
    camDataBytes[i] = (Byte)(CamData[i] / 256);

Color[] palette = new Color[256];
for(Int32 i = 0; i < 256; i++)
    palette[i] = Color.FromArgb(i,i,i);

using(Bitmap b = BuildImage(camDataBytes, 320, 240, 320, PixelFormat.Format8bppIndexed, palette, null))
    b.Save(@"C:\test.bmp", ImageFormat.Bmp); 

The BuildImage function to create an image out of a byte array can be found here. Assuming the image data is compact 320x240, the stride of the final byte array should be exactly the width, and thus 320.

Try this:

/// From stream to bitmap...
FileStream fs = new FileStream("test.bmp", FileMode.Open);
Bitmap bmp = new Bitmap(fs);