[XeTeX] [OT?] "Optimized" PDFs?

[Jonathan Kew]

On 16 Jan 2008, at 9:11 am, Will Robertson wrote:

> On 16/01/2008, at 7:25 PM, Martin Schröder wrote:
>
>> Typically, "Optimized" is used as a synonym for Linearized PDF.
>
> Which is "optimal" in as far as that pages of the PDF can be  
> displayed as fast as they can be read and processed -- whereas non- 
> optimal PDF can require a full pass over the document before it's  
> displayed.

Well, it doesn't actually require a "full pass over the document", in  
the sense of actually reading every byte, but it requires random  
access to fragments of the whole document.

> This, particularly, makes reading PDF over the web much more  
> bearable; furthermore, it could dramatically improve the display  
> time for TeX document compilation. (If you're looking at page 25 of  
> a 100 page document, you only need to wait for a quarter of the  
> document to be typeset by TeX before you see it.)

Yes, that would be nice.... but it's not likely to happen any time soon.

> I don't know if it's actually possible to produce linear PDF in  
> linear manner, however. It might be the case that a post-processing  
> stage is required. Don't ask me, I'm just an engineer.

No, it's not practical. Consider embedded, subsetted fonts, for  
example: the PDF generator can't create the font resource until it  
knows the exact subset of glyphs that need to be included. And it  
can't know this until it gets to the end of the last page.

JK