I try to add one image to my workbook/worksheet.
The Code :
wb.add_worksheet(:name => \"Doc1\", :page_setup => setup, :print_options => opt
In the lines where you set the image width and height you have them very small and you could be overlooking the image as this number is in pixels. Try setting them to higher number.
the following worked for me:
img = File.expand_path(Rails.root+'app/assets/images/result.png')
sheet.add_image(:image_src => img, :noMove => true) do |image|
image.width = 100
image.height = 150
image.start_at 2, 2
end