Displaying Images using Win32 API

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Win32

VisualC++

hi Guys.I'm a beginner working with Win32 API. i want to know how to display Large size images(5MP-2592x1944) in Window/Dialog by using StretchDIBits() API function without affecting the Quality of image. WHen i do this by using this function the image is appearing to noisy. Could anyone guide me on this?
My function:

case WM_PAINT:
{
	if(g_flag==1)
	{
		UINT Dx=10,Dy=75,DWidth=1024,DHeight=768;
		hdc = BeginPaint(hDlg, &ps);
		HDC Dhdc=GetWindowDC(hDlg);			
		StretchDIBits(Dhdc,Dx,Dy,DWidth,DHeight,0,0,g_Width,g_Height,g_pRGB_Buffer,&g_Bitmapinfo,DIB_RGB_COLORS,SRCCOPY);
		DeleteDC(hdc);
		DeleteDC(Dhdc);				
	}
	// TODO: Add any drawing code here...
	EndPaint(hDlg, &ps);					
}