Re: Optimising output for screen.

[Alexander Kobel]

On 2010-09-24 17:42, Phil Holmes wrote:
> It's my understanding (correct me if I'm wrong, somebody) that LilyPond
> is optimised neither for screen or print - it outputs as PDF, and so the
> quality of the image seen depends on the quality of the program that
> interprets the PDF. LilyPond is essentially simply telling the PDF
> viewer/printer "draw a line from here to here".

I think that's a point where LilyPond's output is harder to interpret 
than that of other applications:  Lily uses quite sophisticated varying 
line thicknesses, and IIRC, bar lines, staff lines etc. are drawn as 
rectangles.
It comes to no surprise that PostScript /lines/ in, say, Finale files 
are less sensitive to zoom changes.  The viewer can use a single pixel 
as minimum thickness, probably plus antialiasing, no matter if the line 
should actually be thinner.  For screen output, that's perfectly fine. 
On the other side, Lily's /rectangles/ need more involved handling to 
get such tweaks fine.  At least, the viewers don't seem to try a similar 
subpixel-resolution effort for more than lines.

[ All this is pure speculations which I can't back up.  I don't /know/ 
for sure whether the viewers take such an approach, and what exactly the 
PDF instructions generated by different engravers, including LilyPond, 
are.  But I have the strong suspicion from several files I've seen that 
it's not too far from the truth. ]

In summary, I like the approach taken by LilyPond for it's superb 
printed output.  If it's "just" a matter of exchanging line and 
rectangle commands, there might be way to yield better results, but I'm 
certain the different options have already been considered for the 
current implementation in a wider context than just this.
The only thing that really bugs me for the time being is that in several 
viewers and small zoom levels, the staff line-note head-fitting is 
really bad.  (This includes Adobe Reader, Evince and Okular, but not 
MacOS X preview, IIRC.)  No clue if we can change this with Lily's code, 
though.

Just my two pence...


Cheers,
Alexander