pdfimager

R-check

pdfimager - Extract images from pdfs

Docs: https://sckott.github.io/pdfimager/

This packages uses sys R package to “shell out” to pdfimages. Apparently pdfimages is not in poppler cpp, so is not in pdftools R pkg

Install pdfimages

pdfimages is installed when you install poppler

Installation instructions can be found at https://poppler.freedesktop.org/

Install pdfimager 

# install.packages("pak")
pak::pak("sckott/pdfimager")

Set the path

Some users may need to manually set the path to pdfimages.

You can do so with a function in this package like

or set the path for pdfimages before starting R with an env var like:

PDFIMAGER_PATH=C:/some/path/to/poppler/24/bin/pdfimages.exe R

Or set within R like:

Sys.setenv(PDFIMAGER_PATH="C:/some/path/to/poppler/24/bin/pdfimages.exe")

help info 

pdimg_help()
#> pdfimages version 24.04.0
#> Copyright 2005-2024 The Poppler Developers - http://poppler.freedesktop.org
#> Copyright 1996-2011, 2022 Glyph & Cog, LLC
#> Usage: pdfimages [options] <PDF-file> <image-root>
#>   -f <int>                 : first page to convert
#>   -l <int>                 : last page to convert
#>   -png                     : change the default output format to PNG
#>   -tiff                    : change the default output format to TIFF
#>   -j                       : write JPEG images as JPEG files
#>   -jp2                     : write JPEG2000 images as JP2 files
#>   -jbig2                   : write JBIG2 images as JBIG2 files
#>   -ccitt                   : write CCITT images as CCITT files
#>   -all                     : equivalent to -png -tiff -j -jp2 -jbig2 -ccitt
#>   -list                    : print list of images instead of saving
#>   -opw <string>            : owner password (for encrypted files)
#>   -upw <string>            : user password (for encrypted files)
#>   -p                       : include page numbers in output file names
#>   -print-filenames         : print image filenames to stdout
#>   -q                       : don't print any messages or errors
#>   -v                       : print copyright and version info
#>   -h                       : print usage information
#>   -help                    : print usage information
#>   --help                   : print usage information
#>   -?                       : print usage information

pdf image metadata 

x <- system.file("examples/BachmanEtal2020.pdf", package="pdfimager")
pdimg_meta(x)
#> [[1]]
#> # A tibble: 3 × 16
#>    page   num type  width height color  comp   bpc enc   interp object    ID
#>   <int> <int> <chr> <int>  <int> <chr> <int> <int> <chr> <chr>   <int> <int>
#> 1     5     0 image  1024    573 rgb       3     8 jpeg  yes       178     0
#> 2     8     1 image  1024   1001 rgb       3     8 jpeg  yes       146     0
#> 3    11     2 image  1024    988 rgb       3     8 jpeg  yes       110     0
#> # ℹ 4 more variables: `x-ppi` <int>, `y-ppi` <int>, size <chr>, ratio <chr>

pdf images 

x <- system.file("examples/BachmanEtal2020.pdf", package="pdfimager")
pdimg_images(x)
#> [[1]]
#> # A tibble: 3 × 17
#>   path       page   num type  width height color  comp   bpc enc   interp object
#>   <chr>     <int> <int> <chr> <int>  <int> <chr> <int> <int> <chr> <chr>   <int>
#> 1 /var/fol…     5     0 image  1024    573 rgb       3     8 jpeg  yes       178
#> 2 /var/fol…     8     1 image  1024   1001 rgb       3     8 jpeg  yes       146
#> 3 /var/fol…    11     2 image  1024    988 rgb       3     8 jpeg  yes       110
#> # ℹ 5 more variables: ID <int>, x.ppi <int>, y.ppi <int>, size <chr>,
#> #   ratio <chr>

filter images

does a variety of thing to filter images by their metadata, some are configureable

x1 <- system.file("examples/Tierney2017JOSS.pdf", package="pdfimager")
x2 <- system.file("examples/vanGemert2018.pdf", package="pdfimager")
res <- pdimg_images(c(x1, x2))
vapply(res, NROW, 1)
#> [1] 6 8
out <- pdimg_filter(res)
vapply(out, NROW, 1)
#> [1] 1 8

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