Load an image into a bitmap

I have some raw 8-bit grayscale data that I want to load into a bitmap.  Can anyone give me directions
   on how to load this data and display it in a CFormView.  I'm using VC5.0 and MFC. Thanx

   zeekial@yahoo.
zeekialAsked:
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RONSLOWConnect With a Mentor Commented:
You can simply create a compatible bitmap of the appropriate size, create a DC for it, and then use a loop that does a SetPixel for each pixel in the drawing setting its RGB values to be the same.

You don't _need_ to create a palette .. only if your dispaly has a limited number of colours (<16bit colour say) and you want to see all your grey scale levels.  Without a palette, windows will map your colours to the nearest colour available in the current palette.

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chensuCommented:
You need to convert the raw 8-bit grayscale data into a DIB.

1. Read the data into memory.
2. Create a grayscale palette.
3. Form the data and the palette to a DIB.
4. Display it.

Look into the MFC sample "DIBLOOK: Illustrates the Use of DIBs and Color Palettes" and the Win32 sample "Mypal: Palette Management Example".
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zeekialAuthor Commented:
Here's some code to show you where I stand:

      int fh;
      char buffer[60000];
      unsigned int nbytes = 60000;

      fh = open("imagefile",O_RDONLY)
      read(fh, buffer, nbytes);

      now all my data is in character buffer "buffer".  How do I make a grayscale palette and how do I put this buffer into a DIB and display?  Which functions do I use?  
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RONSLOWCommented:
SetPixelV is quicker, BTW than SetPixel

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RONSLOWCommented:
try something like this ...

  CBitmap bitmap;
  CDC dcMem;
  dcMem.CreateCompatibleDC(NULL);
  bitmap.CreateCompatibleBitmap (hdc, width, height);
  CBitmap* pbitmapOld = dcMem.SelectObject(&bitmap);
  int i = 0;
  for (int x = 0; x < width; x++) {
    for (int y = 0; y < height; y++) {
      char grey = buffer[i++];
      dcMem.SetPixelV (x,y,RGB(grey,grey,grey));
    }
  }
  dcMem.SelectObject(pbitmapOld);

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chensuCommented:
>You don't _need_ to create a palette .. only if your dispaly has a limited number of colours (<16bit colour say) and you want to see all your grey scale levels.

Nowadays, there are still a lot of systems working on 256-color mode.

>Without a palette, windows will map your colours to the nearest colour available in the current palette.

Yes. In this case, the display will be likely looking ugly since you cannot guarantee the current palette contains enough grayscale entries (RGB(x, x, x)).

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RONSLOWCommented:
The code above can be changed to create a true colour DIB (no palette required CreateDIBSection) and the set the pixels.  The palette manipulation can then be done at display time.

Alternatively, create a compatible bitmap (as above) and a use palette.

NOTE: If using CreateDIBSection, you can get back a points to the array of pixel values, and set them diretcly without using SetPixelV.
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