FlexCelPdfExport.ExportSheetBackgroundImages Property
If false (the default) then the background images in the sheet won't be exported. Note that Excel doesn't print or export background images, and when it shows them on the screen they look the same no matter the sheet zoom. When you set this to true we will try to export the image, but it will grow and shrink when you zoom, making it look different from what Excel shows.
Syntax
Namespace: FlexCel.Render
public virtual Boolean ExportSheetBackgroundImages { get; set; }