GDI: Pixel intensity to grayscale bitmap drawing issue, MFC

[vkinra]

Hi,

I am reading some image data out of a camera pixels and have extracted the raw pixel intensity. Each "pixel" on the Camera sensor has either a R,G, or B filter that gives the intensity of the 'R', 'G', or 'B' 'pixel'. I read this data and then extract and store the individual R, G, or B pixel intensities into 3 separate 2d unsigned char arrays called m_ptrRed2DPostDecimationArray. m_ptrGreen2DPostDecimationArray, and m_ptrBlue2DPostDecimationArray. Now I can use SetPixel to display the extracted R, G, and B in 3 separate 'R', 'G', or 'B' window areas. I can display them either in color or grayscale through:
For grayscale: dc.SetPixel(j, i, RGB(theApp.m_ptrRed2DPostDecimationArray[i][j], theApp.m_ptrRed2DPostDecimationArray[i][j], theApp.m_ptrRed2DPostDecimationArray[i][j]));
For color: dc.SetPixel(j, i, RGB(theApp.m_ptrRed2DPostDecimationArray[i][j], 0, 0));

However, I realize SetPixel is very ineffecient so looking at other ways to display. I only need the 8 bit grayscale image so was hoping that I could achieve it using CreateBitmap. m_ptrRed2DPostDecimationArray is a BYTE array (actually unsigned char) that holds the 8 bit raw pixel intensities from the camera pixels that have a red filter on them. Here is my current code (that does not work):

void CVC_ExampleDlg::OnPaint() 
{
        CDC *pDC = GetDC();
 
        BOOL retval = m_redBitmap.CreateBitmap(600, 200, 1, 8, theApp.m_ptrRed2DPostDecimationArray);
 
        CDC memDC; 
        memDC.CreateCompatibleDC(pDC); 
        memDC.SelectObject(&m_redBitmap);
        retVal = pDC->BitBlt(0, 0, 600, 200, &memDC, 0, 0, SRCCOPY);
        memDC.DeleteDC();
                                ReleaseDC(pDC);
        CDialog::OnPaint();
}
 

Now I know I can create a grayscale palette and use the raw data as an index to that palette but it seems to me that CreateBitmap has that built in functionality. I mean it seems like that when I give it 1 color plane and 8bpp, it should automatically create a grayscale 8bit bitmap, no?

Can anyone see what I'm doing wrong. I mean all I want is that I already have the pixel intensity from 0-255 (8 bit) in a byte array. Since I just only want a grayscale bitmap, creating a grayscale palette and indexing it seems overkill especially when CreateBitmap seems to (theoretically) encapsulate that functionality.

I guess, if my question is clear enough, what is the easiet and/or most efficiect way to create a 8bit grayscale image from the raw pixel intensity value from 0-255?

Thank you,

-Vivek Kinra