public class Feature : Row, System.IDisposable  

public async Task ReadBlobField(Table table, QueryFilter queryFilter, string blobFieldName)
{
    await ArcGIS.Desktop.Framework.Threading.Tasks.QueuedTask.Run(() =>
    {
        const string imageFileBaseName = "C:\\path\\to\\image\\directory\\Image";

        // for each row that satisfies the search criteria, write the blob field out to an image file
        using (RowCursor rowCursor = table.Search(queryFilter))
        {
            int fileCount = 0;
            while (rowCursor.MoveNext())
            {
                using (Row row = rowCursor.Current)
                {
                    // Read the blob field into a MemoryStream
                    MemoryStream memoryStream = row[blobFieldName] as MemoryStream;

                    // Create a file
                    using (FileStream outputFile = new FileStream(imageFileBaseName + fileCount.ToString(), FileMode.Create, FileAccess.Write))
                    {
                        // Write the MemoryStream into the file
                        memoryStream.WriteTo(outputFile);
                    }
                }
            }
        }
    });
}