Types of original images in the digital collections
TIFF
Black and white colorspace
RGB colorspace
PDF
Diagnostics for derivative generation software
vips --version vipsthumbnail test.pdf vipsthumbnail color.tiff --eprofile sRGB2014.icc vipsthumbnail black_and_white.tiff --eprofile sRGB2014.icc
Software setups
# | Aptfile | Buildpack | Results |
---|---|---|---|
1 | mediainfo | heroku-community/apt https://github.com/machinio/heroku-buildpack-vips heroku/ruby |
TIFFS work |
2 | libvips-tools | heroku-community/apt heroku/ruby |
Color TIFFs work B&W TIFFs don’t work PDFs work |
3 | As in 3 | As in 3 |
All TIFFS work. Removing |
4 | mediainfo | heroku-community/apt |
|
5 | mediainfo | as in 4 | as in 4 |
6 | mediainfo | heroku-community/apt | 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 byvipsthumbnail
.