// Basic Example:
DicomImage image = new DicomImage("your_dicom_image.dcm");
image.SetSimpleMasking(1, MaskMode.AverageSubtraction);
                
// Retrieving masking values from the DICOM image
DicomImage image = new DicomImage("your_dicom_image.dcm");
MaskMode mode = MaskMode.AverageSubtraction;
List<int> maskFrameNumbers = new List<int>() { 1 };
                    
// Retrieve Mask Subtraction Sequence if it exists 
var maskSubtractionSequence = image.DataSet[Keyword.MaskSubtractionSequence].Value as DicomDataSetCollection;
var firstItem = maskSubtractionSequence[0];
if (firstItem[Keyword.MaskOperation].ExistsWithValue)
{
    string maskOperation = firstItem[Keyword.MaskOperation].Value.ToString().ToUpper();
    if (maskOperation != null)
        mode = GetMaskMode(maskOperation);
}
                    
if (firstItem[Keyword.MaskFrameNumbers].ExistsWithValue)
{
    ushort[] maskFrameNumbersUShort = firstItem[Keyword.MaskFrameNumbers].Value as ushort[];
    maskFrameNumbers = maskFrameNumbersUShort.Select(f => (int)f).ToList();
}
                    
// Apply simple masking with extracted mask frames and mode
image.SetSimpleMasking(maskFrameNumbers.ToArray(), mode);
                    
private MaskMode GetMaskMode(string dicomMaskOperation)
{
    switch (dicomMaskOperation)
    {
        case "AVG_SUB":
            return MaskMode.AverageSubtraction;
        case "MIN":
            return MaskMode.Minimum;
        case "MAX":
            return MaskMode.Maximum;
        case "TID":
            return MaskMode.TimeDifference;
        case "REV_TID":
            return MaskMode.ReverseTimeDifference;
        default:
            return MaskMode.None; 
    }
}