Derivative generation on Heroku

Types of original images in the digital collections

vips --version
vipsthumbnail test.pdf
vipsthumbnail color.tiff --eprofile sRGB2014.icc
vipsthumbnail black_and_white.tiff --eprofile sRGB2014.icc

#	Aptfile	Buildpack	Results
1	mediainfo imagemagick poppler-utils	heroku-community/apt https://github.com/machinio/heroku-buildpack-vips heroku/ruby	`vips-8.10.2-Mon Oct 12` `vips -l \| grep -i pdf` is blank - no poppler support, so PDFs don’t work (See note 1) TIFFS work
2	libvips-tools mediainfo imagemagick poppler-utils	heroku-community/apt heroku/ruby	`vips-8.9.1-Sun Feb 23 08:51:26 UTC 2020` Color TIFFs work B&W TIFFs don’t work PDFs work
3	As in 2	As in 2	`vips-8.9.1-Sun Feb 23 08:51:26 UTC 2020` PDFs work All TIFFS work. Removing `--eprofile srgb_profile_path` from the arguments to `vipsthumbnail` in the code (docs) avoids the error described in issue 942 (See note 2)
4	mediainfo imagemagick poppler-utils	heroku-community/apt https://github.com/brandoncc/heroku-buildpack-vips heroku/ruby	`vips: error while loading shared libraries: libpoppler-glib.so.8: cannot open shared object file: No such file or directory`
5	mediainfo imagemagick	as in 4	as in 4
6	mediainfo imagemagick	heroku-community/apt https://github.com/brandoncc/heroku-buildpack-vips-h20 heroku/ruby	as in 4

Note 1: Eddie believes option 1 did work for much of the evaluation period for Heroku, but as of summer 2021 it didn’t.
Note 2: Solution 3 is a band-aid; it violates the rule implicit in the code that all TIFF derivatives should have their derivatives encoded as srgb, including the derivatives of B&W originals. I interpret the documentation as meaning that the icc profile of originals is reused in their derivatives, but further research is needed.
identify -verbose graphics_file.tiff | grep Colorspace can be used to elucidate what happens to various types of original after being processed by vipsthumbnail.