Types of original images in the digital collections
TIFF
Black and white colorspace
RGB colorspace
PDF
Diagnostics for derivative generation software
Run the following commands in a heroku dyno. Your results may vary slightly, but anything that is way off should be seen as a red flag.
heroku run bash mediainfo --version # Normal output: # MediaInfo Command line, # MediaInfoLib - v19.09 convert -version # Normal output: # Version: ImageMagick 6.9.10-23 Q16 x86_64 20190101 https://imagemagick.org # Copyright: © 1999-2019 ImageMagick Studio LLC # License: https://imagemagick.org/script/license.php # Features: Cipher DPC Modules OpenMP # Delegates (built-in): bzlib djvu fftw fontconfig freetype jbig jng jpeg lcms lqr ltdl lzma openexr pangocairo png tiff webp wmf x xml zlib pdfunite -v # Normal output: # pdfunite version 0.86.1 vips --version # Normal output: # vips-8.10.6-Tue Mar 23 20:52:58 UTC 2021 vips -l | grep -o '[a-z_]*pdf[a-z_]*' # Normal output: # pdfload_base # pdfload # pdf # pdfload_buffer # pdfload_source cd tmp PROFILE=`ls ../vendor/bundle/ruby/*/gems/kithe-*/lib/vendor/icc/sRGB2014.icc` wget https://digital.sciencehistory.org/downloads/m3zcuho -O b_w.tiff wget https://digital.sciencehistory.org/downloads/1h16b9n -O color.tiff wget https://digital.sciencehistory.org/downloads/519ucnx -O normal.pdf vipsthumbnail color.tiff --eprofile $PROFILE vipsthumbnail b_w.tiff --eprofile $PROFILE vipsthumbnail normal.pdf identify *.jpg | grep sRGB # Normal output (ignore warnings): # tn_b_w.jpg JPEG 128x108 128x108+0+0 8-bit sRGB 23603B 0.000u 0:00.000 # tn_color.jpg JPEG 128x96 128x96+0+0 8-bit sRGB 11880B 0.000u 0:00.000 # tn_normal.jpg JPEG 99x128 99x128+0+0 8-bit sRGB 1619B 0.010u 0:00.000
Software setups
We’ve been through 5 of these since starting to investigate Heroku.
# | Aptfile | Buildpack | Results |
---|---|---|---|
1 | libvips-tools mediainfo imagemagick poppler-utils | heroku-community/apt heroku/ruby |
Color TIFFs work PDFs work |
2 | libvips-tools mediainfo imagemagick poppler-utils | heroku-community/apt heroku/ruby |
All TIFFS work Removing |
3 | mediainfo imagemagick poppler-utils | heroku-community/apt https://github.com/machinio/heroku-buildpack-vips heroku/ruby |
At some point in 2021, All TIFFS work |
4 | mediainfo imagemagick libglib2.0-0 libglib2.0-dev libpoppler-glib8 | heroku-community/apt https://github.com/brandoncc/heroku-buildpack-vips heroku/ruby |
PDFs work All TIFFS work |
Note: Row 2 was a band-aid; it 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
.