科学级CCD相机，拍照后的数据保存问题

Question

程序开始时，创建一个保存图像的数组，其大小为采集到图像大小的2倍，当数据填充完毕后，保存时，图像数组又除以了2。为什么要乘以2再除以2。
#include

// Import the type library to create an easy to use wrapper class
// Add the path to apogee.dll to your project file
#import "Apogee.DLL" no_namespace

void main()
{
ICamera2Ptr AltaCamera; // Camera interface
ICamDiscoverPtr Discover; // Discovery interface
HRESULT hr; // Return code
FILE* filePtr; // File pointer
unsigned short NumImages; // Number of images to take
unsigned short i; // Counter
unsigned short* pBuffer;
unsigned short* pBufferIterator;
unsigned long ImgSizeBytes;
char szFilename[80]; // File name

printf( "Apogee Alta Bulk Sequence Sample Applet\n" );

CoInitialize( NULL );           // Initialize COM library

// Create the ICamera2 object
hr = AltaCamera.CreateInstance( __uuidof( Camera2 ) );
if ( SUCCEEDED(hr) )
{
    printf( "Successfully created the ICamera2 object\n" );
}
else
{
    printf( "Failed to create the ICamera2 object\n" );
    CoUninitialize();       // Close the COM library
    return;
}

// Create the ICamDiscover object
hr = Discover.CreateInstance( __uuidof( CamDiscover ) );
if ( SUCCEEDED(hr) )
{
    printf( "Successfully created the ICamDiscover object\n" );
}
else
{
    printf( "Failed to create the ICamDiscover object\n" );
    AltaCamera = NULL;      // Release ICamera2 COM object
    CoUninitialize();       // Close the COM library
    return;
}

// Set the checkboxes to default to searching both USB and 
// ethernet interfaces for Alta cameras
Discover->DlgCheckEthernet  = true;
Discover->DlgCheckUsb       = true;

// Display the dialog box for finding an Alta camera
Discover->ShowDialog( true );

// If a camera was not selected, then release objects and exit
if ( !Discover->ValidSelection )
{
    printf( "No valid camera selection made\n" );
    Discover    = NULL;     // Release ICamDiscover COM object
    AltaCamera  = NULL;     // Release ICamera2 COM object
    CoUninitialize();       // Close the COM library
    return;
}

// Initialize camera using the ICamDiscover properties
hr = AltaCamera->Init( Discover->SelectedInterface, 
                       Discover->SelectedCamIdOne,
                       Discover->SelectedCamIdTwo,
                       0x0 );

if ( SUCCEEDED(hr) )
{
    printf( "Connection to camera succeeded.\n" );
}
else
{
    printf( "Failed to connect to camera" );
    Discover    = NULL;     // Release Discover COM object
    AltaCamera  = NULL;     // Release ICamera2 COM object
    CoUninitialize();       // Close the COM library
    return;
}

// Query user for number of images in the sequence
printf( "Number of images in the sequence:  " );
scanf( "%d", &NumImages );
printf( "Preparing sequence of %d images.\n", NumImages );

// Set the image count
AltaCamera->ImageCount = NumImages;

// Query the camera for a full frame image
long ImgXSize = AltaCamera->ImagingColumns;
long ImgYSize = AltaCamera->ImagingRows;

// Display the camera model
_bstr_t szCamModel( AltaCamera->CameraModel );
printf( "Camera Model:  %s\n", (char*)szCamModel );

// Display the driver version
_bstr_t szDriverVer( AltaCamera->DriverVersion );
printf( "Driver Version:  %s\n", (char*)szDriverVer );

// Toggle the sequence download variable
AltaCamera->SequenceBulkDownload = true;

// Allocate memory and calculate a byte count.  For bulk
// sequences, the buffer should be sized to include all images
pBuffer         = new unsigned short[ ImgXSize * ImgYSize * NumImages];
ImgSizeBytes    = ImgXSize * ImgYSize * 2;

// Do a 0.001s dark frame (bias)
printf( "Starting camera exposure...\n" );
AltaCamera->Expose( 0.001, false );

// Check camera status to make sure image data is ready
while ( AltaCamera->ImagingStatus != Apn_Status_ImageReady );

// Get the image data from the camera
printf( "Retrieving image data from camera...\n" );
AltaCamera->GetImage( (long)pBuffer );

pBufferIterator = pBuffer;

// Write the test images to different output file (overwrite if it already exists)
// In this process, we are dividing the single image buffer into the separate
// images that comprise the bulk data set.
for ( i=1; i<=NumImages; i++ )
{
    sprintf( szFilename, "BulkImage%d.raw", i );

    filePtr = fopen( szFilename, "wb" );

    if ( filePtr == NULL )
    {
        printf( "ERROR:  Failed to open file for writing output data." );
    }
    else
    {
        printf( "Wrote image data to output file \"%s...\"\n", szFilename );

        fwrite( pBufferIterator, sizeof(unsigned short), (ImgSizeBytes/2), filePtr );
        fclose( filePtr );

        if ( i < NumImages )
        {
            // Only change the pointer for the first n-1 images
            pBufferIterator += (ImgSizeBytes/2);
        }
    }
}

printf( "Sequence Count:  %d\n", AltaCamera->SequenceCounter );

// Delete the memory buffer for storing the image
delete [] pBuffer;

// Release allocated objects.  
Discover    = NULL;     // Release ICamDiscover COM object
AltaCamera  = NULL;     // Release ICamera2 COM object

CoUninitialize();       // Close the COM library

}

Answer 1

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