Types of original images in the digital collections
TIFF
Black and white colorspace
RGB colorspace
PDF
Software needed to generate derivatives:
See Aptfile below.
Diagnostics for derivative generation software
Code Block |
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vips --version
vipsthumbnail test.pdf
vipsthumbnail color.tiff --eprofile sRGB2014.icc
vipsthumbnail black_and_white.tiff --eprofile sRGB2014.icc |
Software setups
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#
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Aptfile
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Buildpack
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Results
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1
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These are now automated in a suite of tests you can run with. ./bin/rspec system_env_spec
. See https://github.com/sciencehistory/scihist_digicoll/blob/master/system_env_spec/README.md .
See the page’s history for how we did this in the past.
Software setups
# | Aptfile | Buildpack | Results | ||||
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1 |
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Color TIFFs work PDFs work | ||||
2 |
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All TIFFS work Removing | ||||
3 |
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At some point in 2021, |
started returning blank - no |
. All TIFFS work |
4 |
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imagemagick
poppler-utils
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Color TIFFs work
B&W TIFFs don’t work
PDFs work
3
As in 3
PDFs work All TIFFS work Combined audio derivatives don’t work | |||||||
5 |
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PDFs work All TIFFS |
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
imagemagick
poppler-utils
5
mediainfo
imagemagick
as in 4
as in 4
6
mediainfo
imagemagick
work Combined audio derivatives work again (see issue 1448)
| ||
6 |
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vips: error while loading shared libraries: libpoppler-glib.so.8: cannot open shared object file: No such file or directory
PDF on-demand stopped working in staging, so we added poppler-utils back into aptfile. | ||
7 |
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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.
...
OCR. Note we are removing |
Note: Row 2 was a band-aid; it violates violated 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
.