Re: Latest lilypond git master creating PDF 1.4 files instead of 1.7

[David Kastrup]

"H. S. Teoh" <hsteoh@quickfur.ath.cx> writes:

> On Sat, Sep 11, 2021 at 09:35:00PM +0200, Valentin Petzel wrote:
>> From what I see pdftops appears to be intelligent enough to rasterize
>> the file only if it does actually contain transparency. If it does it
>> uses a much less smooth rasterization that is probably not fit for
>> printing, so be careful with this! See the attached picture for a
>> comparisation, the left one is poppler (pdftops), the right one gs
>> (pdf2ps).
>
> I experimented with pstops, and it does seem to produce a non-rasterized
> PS file, which can then be converted back to PDF without transparency,
> thus sidestepping this issue.  I'll use that as a workaround for now.
> :-D
>
>
> [...]
>> But anyway. Usually there should not be any reason to convert from pdf
>> to ps, apart from printing or doing ps-style manipulations. But ps is
>> only a subset of pdf, so the conversion in that direction cannot
>> always be done in an acceptable manner.
>
> I discovered that converting the pdf to ps and back again significantly
> reduces the file size.  So it's kinda my poor-man's way of compressing
> pdfs.  Of course, this only works if your pdf doesn't contain any
> features incompatible with ps, which in my case is true.  And now that I
> know that pdftops does a proper job with the conversion even when there
> is transparency, it's a sufficiently-acceptable solution to this issue.

It may be worth noting that somewhat counterintuitively running ps2pdf
on a PDF file tends to work fine, producing a PDF file again in a single
step without an intermediate ps file.

-- 
David Kastrup