Nathaniel wrote: What do you need TIFF files for that PNG can't handle? I'm genuine interested; there are things the TIFF format can do that PNG can't, but I'd like to know which features you need and why. -- Ilmari Karonen

On 12/1/06, Nathaniel <spangineer(a)gmail.com> wrote: http://en.wikisource.org/wiki/Wikisource:Scriptorium/Archives/2006/11#TIFF_…. PNG and TIFF are in the exact same boat in this regard. JPEG isn't necessarily bigger, but rather we should expect objectionable artifacts in JPEGs. The misconception that PNGs are somehow low quality for continuous tone images appears to be rampant in our community and it needs to be stopped. What PNGs actually are is space inefficient, and while people might argue that *space is cheap*, bandwidth is not and until we have cross-format thumbnailing, size will remain a major factor in our selection of upload formats. We also have the worry that "TIFF" doesn't actually tell us what it is.. TIFF is one of those generic wrappers which people can (and do) shove all sorts of random crap into... including proprietary/patented formats (I've seen TIFFs stuffed with Mr.SID for digital orthophotography), although it's not that common since most things can't read such tiffs. The best format for this is dejavu, which we support, but we don't have support for either the browser plugins or serverside autoconversion. The only advantage I see for tiff is that some of the browser plugins have nice navigation abilities.. but the same is true for dejavu... if we're going to put something up that needs a browser plugin it should be the free software solution. Dejavu also happens to have MUCH better compression, and it would also be an acceptable lossy solution for photographs as well.. better than jpeg.

On 12/1/06, Gregory Maxwell &lt;gmaxwell(a)gmail.com&gt; wrote: The best format for this is dejavu, which we support, but we don't Sorry, dejavu isn't yet supported in the ProofreadPage extension. This extension is used to proofreading works at Wikisource. http://en.wikisource.org/wiki/Help:Side_by_side_image_view_for_proofreading http://bugzilla.wikimedia.org/show_bug.cgi?id=7957 <small>http://bugzilla.wikimedia.org/show_bug.cgi?id=7534</small>

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Sherool wrote: Which, of course, is an ability that's very poorly supported. - -- brion vibber (brion @ pobox.com)

On Fri, 01 Dec 2006 20:47:05 +0100, Gregory Maxwell &lt;gmaxwell(a)gmail.com&gt; wrote: Ah, I see. I'm so out of touch with all these "new" (to me) formats :-O I still have some old IFF images from the Amiga days, is that a supported format? :P -- [[:en:User:Sherool]]

Lars Aronsson wrote: Have you tried a comparison against a 600 dpi bitonal PNG? The DEFLATE compression used in PNGs may or may not be as effective for bitone images as G4, but it should still handle them pretty well. -- Ilmari Karonen

On 12/2/06, Lars Aronsson &lt;lars(a)aronsson.se&gt; wrote: Well, you should compare apples to apples. The image you specified becames only 58 kbytes wen saved as 1-bit (bitonal) PNG. And bitmapped formats like PNG and TIFF have no concept of "dpi"- that's an external manipulation made by the printing program. You need to compare images with the same pixel sizes. Ciao, Alfio

Alfio Puglisi wrote: Sorry for the confusion. Allow me to clarify this. Were you able to read the text from that 58 kbyte image? This page was original scanned in 600 dpi bitonal and saved as TIFF G4, a format supported by most scanner software. The image is 3616x5550 pixels and the resulting file is 196 kbyte. You can get it here: http://runeberg.org/img/nfad-0670.tif Since most web browsers don't support TIFF, and since 600 dpi is nowhere near the resolution of most computer screens, the web presentation uses a downscaled (by a scale factor 1:4) grayscale image instead. The conversion process is roughly: tifftopnm | pngscale .25 | ppmquant 16 | pnmtopng In the resulting image, now 200 kbytes, every 150 pixels correspond to one inch of the printed page, from which it was originally scanned. Thus, I'm using the shorthand terminology that this is now a 150 dpi image. Since most computer screens have a resolution in the rage 100-120 dpi, this means the image is displayed a little "larger than life". Scanning at 600 dpi is something of a standard for printed text. Many scanned books can then be displayed on screen in 120 dpi (downscale 1:5), but this book (an encyclopedia) has small print which is more readable in 150 dpi. You suggest the original TIFF image could be saved as a 1-bit PNG instead, and this is true. The conversion process is: tifftopnm | pnmtopng The resulting image 404 kbytes or twice as large as the TIFF G4 image. You can get this at http://runeberg.org/img/nfad-0670.png -- Lars Aronsson (lars(a)aronsson.se) Aronsson Datateknik - http://aronsson.se

On 12/4/06, Alfio Puglisi &lt;alfio.puglisi(a)gmail.com&gt; wrote: No. Dejavu is, by a mile. [gmaxwell@floodlamp ~]$ cjb2 -losslevel 100 nfad-0670.tif nfad-0670.djvu [gmaxwell@floodlamp ~]$ ls -l nfad-0670.* -rw-rw-r-- 1 gmaxwell gmaxwell 72075 Dec 4 21:55 nfad-0670.djvu -rw-rw-r-- 1 gmaxwell gmaxwell 200865 Dec 4 08:01 nfad-0670.tif [gmaxwell@floodlamp ~]$ cjb2 -lossless nfad-0670.tif nfad-0670.djvu [gmaxwell@floodlamp ~]$ ls -l nfad-0670.* -rw-rw-r-- 1 gmaxwell gmaxwell 128772 Dec 4 21:56 nfad-0670.djvu -rw-rw-r-- 1 gmaxwell gmaxwell 200865 Dec 4 08:01 nfad-0670.tif [gmaxwell@floodlamp ~]$ cjb2 -losslevel 200 nfad-0670.tif nfad-0670.djvu [gmaxwell@floodlamp ~]$ ls -l nfad-0670.* -rw-rw-r-- 1 gmaxwell gmaxwell 35209 Dec 4 21:56 nfad-0670.djvu -rw-rw-r-- 1 gmaxwell gmaxwell 200865 Dec 4 08:01 nfad-0670.tif Even at losslevel 200 zoomed way in, I'd be hard pressed to tell the original from the djvu. Djvu lossy works by reusing whole characters... so it should not adversely impact OCR, although it does not work so well on noisy documents. Even in lossless mode djvu is half the size of the tiff. The free software djvu viewer is very good, easily better than most of the PS and Tiff viewers I've used. Djvu can also produce mixed pages of images and text using the optimal compression method for each type. You can't do that with TIFF in G4 mode. Djvu's lossy compression of photographic material is vastly superior to jpeg (more quality per bit in terms of PSNR, and less objectionable artifacts at low quality levels). Djvu files can also be loaded incrementally.. loading more data as you zoom in. Great for high resolution images like satellite photography or other ridiculous resolution photographs.

On Sun, Dec 03, 2006 at 08:52:31PM +0100, Alfio Puglisi wrote: Well, an inference could be made that when one describes two images with differing DPI renderings that the *final size in inches* is expected to be the same, but you're right: that's expecting too much of the speakers... :-) Cheers, -- jra -- Jay R. Ashworth jra(a)baylink.com Designer Baylink RFC 2100 Ashworth & Associates The Things I Think '87 e24 St Petersburg FL USA http://baylink.pitas.com +1 727 647 1274 (I've been informed that the 'divorce' quote makes me look misogynistic, even though Jennifer Crusie is (pretty obviously) a female romance novelist. So I've removed it. :-)