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Hi Dave, On Sun, Apr 17, 2005 at 11:57:45AM +0100, Dave Pawson wrote: > On Sun, 2005-04-17 at 09:28 +0930, Paul A. Hoadley wrote: > > To keep it simple, I'll stick with line drawing diagrams as the > > type of image, since the considerations are probably different for > > different image types (such as photographs, screenshots, and so > > on). > > So down to vector images, on fo output? For images like line drawings and diagrams, I'd have to say yes. But I suppose you also need to consider the intended use of the final document. If you're publishing a lecture hand-out, a PNG or GIF might be perfectly acceptable, particularly if it has not been scaled. If you're intending to print a book, you would need to use a vector format. > This does narrow down doesn't it! Is SVG the only viable vector > format for HTML then? Still restricted to a browser plug in. As far as I know, yes. > > If the output format can handle it, you are certainly better off > > using a vector format for the image (EPS, SVG, PDF). > > Again showing my ignorance. EPS I knew of, SVG I'm OK with, but PDF > for an image? Sure. PDF is just a page description language, after all. XEP, for example, can include PDF images in a PDF just using the fo:external-graphic element. Think including EPS in PS. > What tools are used to generate them please? I have actually never used Adobe Illustrator, but I'd be surprised if you couldn't output a drawing directly as a PDF. XFig will export as PDF. Failing that, save your image from your favourite vector drawing program as EPS and use ps2pdf to convert. > Do they open in Acrobat reader as any other file? Yes. > > The main issue is scaling. Say your printer can print 600x600 > > DPI, and you have a 2 inch square region on your page for a > > diagram. An EPS image will be rasterised into a 1200x1200 bitmap > > to be placed in that region. Now, if you had a 1200x1200 PNG of > > your diagram, the output would be essentially the same. > > PNG isn't a vector format though Paul... is it? No, it's not. I probably wasn't completely clear there. Say that you know your final output needs to be 2 inches square on a 600x600 DPI printer. You need a 1200x1200 image. You could create an EPS version, and on output it would be rasterised to a 1200x1200 bitmap for printing. Theoretically, you could produce _exactly the same_ bitmap as a PNG. But if you did that, and later needed to put it in a 4 inch square region, the scaled result will look blocky. The EPS image will be re-rasterised to 2400x2400 bitmap with no loss of quality. -- Paul. w http://logicsquad.net/ h http://paul.hoadley.name/
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