OleObject.ImageData

public byte[] ImageData { get; set; }

// Called: Assert.AreEqual(binaryImg[300], objOle.ImageData[300]);
public void OleObject_Property_ImageData()
{
    Workbook workbook = new Workbook();
    byte[] binaryImg = File.ReadAllBytes(Constants.sourcePath + "image1.png");
    //converting attachment data into bytes

    //In real we will get the documents from blob storage, azure
    //Stream stream = DownloadStreamFromBlob(info.StoragePath.Split("/")[0].ToString(), Path.Combine(info.StoragePath.Split("/")[1].ToString(), info.DocumentBlobId));
    //byte[] binaryXlsx = ReadFully(stream);

    int idxOle = workbook.Worksheets[0].OleObjects.Add(0, 0, 60, 60, binaryImg);
    OleObject objOle = workbook.Worksheets[0].OleObjects[idxOle];
    objOle.SetEmbeddedObject(false, binaryImg, Constants.sourcePath + "image1.png", true, "abcd",false);
    Assert.AreEqual(binaryImg[300], objOle.ImageData[300]);
    workbook.Save(Constants.destPath + "example.xlsx");
}