josch/img2pdf
3
6
Fork 10
Code Issues 21 Pull requests 5 Projects Releases 3 Wiki Activity

README.md: document how to remove alpha channel and --rotation=ifvalid

Browse source
This commit is contained in:
Johannes Schauer Marin Rodrigues 2021-08-14 10:19:46 +02:00
parent 5c617965f5
commit 55d589a548
Signed by: josch
GPG key ID: F2CBA5C78FBD83E1
1 changed files with 11 additions and 1 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

12
README.md
View file

@ -80,7 +80,17 @@ Bugs
- Input images with alpha channels are not allowed. PDF only supports - Input images with alpha channels are not allowed. PDF only supports
transparency using binary masks but is unable to store 8-bit transparency transparency using binary masks but is unable to store 8-bit transparency
information as part of the image itself. But img2pdf will always be lossless information as part of the image itself. But img2pdf will always be lossless
and thus, input images must not carry transparency information. and thus, input images must not carry transparency information. You can
remove the alpha channel for example with imagemagick:
convert input.png -background white -alpha remove -alpha off output.png
- An error is produced if the input image is broken. This commonly happens if
the input image has an invalid EXIF Orientation value of zero. Even though
only nine different values from 1 to 9 are permitted, Anroid phones and
Canon DSLR cameras produce JPEG images with the invalid value of zero.
Either fix your input images with `exiftool` or similar software before
passing the JPEG to `img2pdf` or run `img2pdf` with `--rotation=ifvalid`.
- img2pdf uses PIL (or Pillow) to obtain image meta data and to convert the - img2pdf uses PIL (or Pillow) to obtain image meta data and to convert the
input if necessary. To prevent decompression bomb denial of service attacks, input if necessary. To prevent decompression bomb denial of service attacks,