thank you for fast response!
I’ve checked the related code and it seems the result is a side-effect from PDF/A conversion.
The code itself looks similar to this:
var book = new Workbook(dir + “image_transparency_problem.xlsx”);
using (Stream lStream = new MemoryStream())
Aspose.Pdf.Document lPdfA = new Aspose.Pdf.Document(lStream);
using (MemoryStream lLogStream = new MemoryStream())
bool lSucceed = lPdfA.Convert(lLogStream, Aspose.Pdf.PdfFormat.PDF_A_1B, Aspose.Pdf.ConvertErrorAction.Delete);
lPdfA.Save(dir + “output.pdf”);