Dear Evgeniy Pashin,
1: The Document.Import(string file, ImageImportOptions options, View view, out Element element) has no any problem to import image to project; From UI, we can insert image via Insert Tab\Import Panel\Image, the Import API just does what UI does.
2: If you want to insert image to TableCell, you should consider another API: TableSectionCell.InsertImage(); besides, to insert image, you should build one ImageType firstly; following code demonstrates how to achieve this:
/// <summary>
/// Builds one ImageType and then import it to schedule cell.
/// </summary>
public void InsertImage2Schedule()
{
// build one ImageType from image in disk
Document revitDoc = this.ActiveUIDocument.Document;
ElementId imageId = ElementId.InvalidElementId;
using(Transaction tran = new Transaction(revitDoc, "Image Type"))
{
tran.Start();
ImageType imageTpe = ImageType.Create(revitDoc, "C:\\ThumbNail.jpg");
imageId = imageTpe.Id;
tran.Commit();
}
//
// insert this image to schedule cell
ViewSchedule vs = this.ActiveUIDocument.ActiveView as ViewSchedule;
TableData td = vs.GetTableData();
TableSectionData tsd = td.GetSectionData(0);
if(tsd.IsValidImageSymbolId(imageId))
{
using(Transaction tran = new Transaction(revitDoc, "Insert Image"))
{
tran.Start();
tsd.InsertImage(0, 0, imageId);
tran.Commit();
}
}
}