Extract images that are referenced through ExtGState #1183
Description
Images that are referenced through ExtGState are not listed or extracted.
Example page.pdf
pdfimages lists:
pdfimages -list page.pdf
page num type width height color comp bpc enc interp object ID x-ppi y-ppi size ratio
--------------------------------------------------------------------------------------------
1 0 image 313 341 rgb 3 8 image no 5 0 301 301 333B 0.1%
1 1 smask 313 341 gray 1 8 image no 5 0 301 301 23.4K 22%
but pdfcpu says 0 images available