peter at silmaril.ie
Sat Dec 15 15:25:21 CET 2018
On 15/12/2018 00:46, Reinhard Kotucha wrote:
> > 1. PNG actually gets converted to the PDF internal format
> > automatically (at a small penalty in terms of speed) so for
> > lots of images, or very large images, use JPG format or
> > preconvert them to PDF;
> Please never recommend to convert PNG to JPEG. JPEG uses lossy
> compression optimized for photographs. For screenshots, for
> instance, PNG is much better because it doesn't suffer from the JPEG
Thank you. Yes, I recommend JPEG for photographs. I had forgotten about
screenshots. I was concentrating on whether it's worth telling people to
preconvert to PDF or not...
> Many people, especially in the Windows world, believe that JPEG
> files are always smaller than PNG files. This is only true if you
> don't care about quality. If you want to achieve same quality (i.e.,
> avoid the JPEG artifacts), a JPEG file is most likely much larger
> than a PNG file.
That's useful information — I haven't used Windows seriously since
before W95, so I am fairly clueless about what Windows people do.
> IMO it's best to teach TeX users to use vector graphics whenever
I do that.
> For everything else PNG is the best choice. JPEG should only be used
> for photographs but nothing else.
That's pretty much it in a nutshell. But there are some people who will
> > 2. It is also of course possible to convert (repackage) your JPG
> > pictures to PDF, using any of the standard graphics
> > conversion/manipulation programs (see § 126.96.36.199 for
> > details). Preconverting all your images to PDF makes them load
> > into your document slightly faster.
> Conversion doesn't make sense here because JPEG is supported by PDF
> natively. Hence, a JPEG file is inserted into a PDF file as-is.
As I understand it, the PDF internal bitmap format is not JPEG but
Adobe's own. Maybe I misunderstood.
> Pre-processing is only useful if the pre-processor is able to do some
I'll skip this: this is a book for beginners.
> > 3. XƎLATEX and PDFLATEX will search for the graphic file by file
> > type, in this order (check for the newest definition in your
> > pdftex.def): .png, .pdf, .jpg, .mps, .jpeg, .jbig2, .jb2, .PNG,
> > .PDF, .JPG, .JPEG, .JBIG2, and .JB2. [...]
> This behaviour doesn't depend on the TeX engine you are using. The
> behaviour is defined in a LaTeX macro package which is used by all
> LaTeX engines, so you could mention LuaTeX as well.
Can you identify which macro package this is? eg graphicx?
> The search order is obviously wrong but can't be changed without
> breaking existing documents. It's wrong to look for .png files before
> looking for .pdf files.
I was just about to ask about that. I wonder why it was chosen that way?
> The solution is not to rely on this order at all.
Which I do in my own documents, so I had better recommend it...
> On Windows Sam2p is part of the TeX Live distribution. No need to
> download anything.
I believe most Windows users don't use the command line anyway.
> BTW, the name of the file format is JPEG, not JPG.
More information about the texhax