test.sh: add comment about dct decoding method

This commit is contained in:
Johannes 'josch' Schauer 2018-08-27 11:42:37 +02:00
parent bd55ac5a45
commit d4700dbf38
Signed by: josch
GPG key ID: F2CBA5C78FBD83E1

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@ -171,6 +171,9 @@ img2pdf "$tempdir/normal.jpg" "$tempdir/out.pdf"
# We have to use jpegtopnm and cannot use djpeg because the latter produces # We have to use jpegtopnm and cannot use djpeg because the latter produces
# slightly different results as well when called like this: # slightly different results as well when called like this:
# djpeg -dct int -pnm "$tempdir/normal.jpg" > "$tempdir/normal.pnm" # djpeg -dct int -pnm "$tempdir/normal.jpg" > "$tempdir/normal.pnm"
# An alternative way to compare the JPG would be to require a different DCT
# method when decoding by setting -define jpeg:dct-method=ifast in the
# compare command.
jpegtopnm -dct int "$tempdir/normal.jpg" > "$tempdir/normal.pnm" 2>/dev/null jpegtopnm -dct int "$tempdir/normal.jpg" > "$tempdir/normal.pnm" 2>/dev/null
compare_rendered "$tempdir/out.pdf" "$tempdir/normal.pnm" compare_rendered "$tempdir/out.pdf" "$tempdir/normal.pnm"