Re the .svg issue, well, I'm glad this didn't turn out to be totally just my cluelessness! Thanks DF & ALE for helping identify the issue.
On the other issue of the .png resolution:
I tried putting this string into the lilypond command line in Atom-package lily-compile's settings:
-danti-alias-factor=10 -dresolution=300
where I had, before, had only
-dresolution=300
and got peculiar results including nothing happening, a partial (?) error message, and making the VI program (Windows free image viewer I use) hang also, so that it displayed only a black screen even on other images, which went away after I closed and restarted it.
So this is why DF said,
"I think that you will need to install ImageMagick."
I may do this although I am not yet convinced of the necessity... (ahem, to be continued.)
When I tried the complete string (as given above by DF) directly in the Windows command line it took a very long time, and finally produced an error message, screen shot attached (for the record, although DF has been over this before.)
a search for "pngtopnm" turned up this page:
http://netpbm.sourceforge.net/doc/pngtopnm.htmlwith this text:
"...
This program is part of Netpbm.
pngtopnm was obsoleted by pngtopam, introduced with Netpbm 10.44 (September 2008). pngtopam is backward compatible with pngtopnm, plus adds many additional functions, including the ability to produce a PAM image that includes a transparency (alpha) channel. Starting in Release 10.48, pngtopnm is just an alias for pngtopam.
pngtopnm remained in the Netpbm package through Release 10.47 because it may have fewer bugs than pngtopam in those releases, and may be faster in some environments. But pngtopnm's incompatibility with the most current PNG libraries makes it impractical to maintain along with pngtopam now.
In releases before 10.48, you can use the pngtopam documentation for pngtopnm, considering the following differences:
pngtopnm options are a subset of pngtopam's, as documented above.
Any change that the pngtopam manual says happened in or after Netpbm 10.44 doesn't apply to pngtopnm.
..."
I also found this by searching "pngtopnm windows"
http://gnuwin32.sourceforge.net/packages/pngutils.htm"PngUtils is a collection of utilities for PNG images: "
list of files including:
"[bullet] PngtoPnm: convert a Portable Network Graphics file into a portable anymap "
This looked like a likely thing instead of Image-Magick...
So I downloaded it and installed it, with more peculiar results, to wit:
I ran the same string from the Windows 7 DOS command line.
Took a long time. Sorry I didn't screen-shot the output. Said something about "renaming file to file.old" and then said, "file exists".
In the output directory there were then two files where there was one before.
One file appeared to be that which I had made with lily-compile an hour before - same date, time, properties, size 191 kilobytes, 300 dpi.
The second file had the same name with extension .png.old, and it is 4 megabtyes !! I took the .old extension off it, and indeed it appears to be a very high res .png file, but of course much too large to be of practical use. I can see part of it with VI, but it won't go small enough to see the whole thing! I tried to open it with Gimp, and Gimp appears to have hung - awaiting developments, it is still sitting there with its little hourglass. I'll give it a while.
Anyway, that's two strikes and one hit: the .svg and the anti-aliased .png have miss-fired, and the hi-res 300 dpi .png output from lilypond is working fine, and can be imported into Scribus routinely, and that's where it makes sense to me to leave it for now. Until I make a test print I have no further criticism of the 191k 300 dpi file, unless it turns out that it doesn't print well (and I could I suppose up the resolution more), but I have no printer these days, ha! So it can wait.