On 9/6/07, Ross Presser <[EMAIL PROTECTED]> wrote: > I used the Any2DjVu Server at > > http://any2djvu.djvuzone.org/any2djvu.php > > to convert this 18Mb full color TIFF to a 38 kilobyte DJVU file. (By the > way, why did you save it with no compression? ZIP compression reduced the > original from 18mb to 15.5 mb ... not much, but a little savings.) > > http://rpresser.googlepages.com/example.djvu (38k) > > There are a number of different freely available DJVU readers; Google is > your friend here. > > When it is initially viewed as a DJVU file, it appears exactly the same as > the color TIFF. But the View menu allows you to see only the black and white > layer, suppressing the color background. (It also suppresses the color > photographs.) Now the black text is easily readable on a white background. > > Viewing only the color layer, we can see the color photos are still there, > as well as some soft residue from the text. > > I wasn't able to easily find a way to export only the b/w layer using the > viewer I have. But I was able to select it and copy it to the clipboard, > then paste it into a new grayscale graphic (in another graphic editor) and > save that. (It claimed to be 3 unique colors, therefore grayscale rather > than true black and white.) The result is here: > > http://rpresser.googlepages.com/example-bw.tif (79k) > > Note the incredible efficiency of DJVU here. The entire layered DJVU file, > with all the color information and appearing identical to the original when > viewed, is half the size of JUST THE TEXT, even when compressed using G4 > compression -- one of the best available for bw images. > > The final step in this work, if desired, would be to extract the color > photos from the color layer, clean them up, and paste them back into the b/w > layer.
Thanks, Ross, for your help. It is quite impressive impressive the amount of size reduction that you achieved! My ultimate goal is to get a pdf from the scanned document. I exported from the djvu viewer with ascii and then I used the command $ convert -monochrome -compress Group4 example.ppm example.pdf Segmentation fault $ getting always a "Segmentation fault". Any ideasto overcome the "Segmentation fault"? Paul > On 8/30/07, Paul Smith <[EMAIL PROTECTED]> wrote: > > On 8/30/07, Ross Presser < [EMAIL PROTECTED]> wrote: > > > The best solution to this problem may be in the domain of JPEG2000 / > djvu > > > image segmentation algorithms. Look up some scanned books on > archive.org, > > > particularly in djvu format. The djvu plugin lets you suppress the > > > background completely ... so identifying what is "background" is part of > the > > > djvu construction. > > > > Thanks, Ross and Anthony. My figure is available at: > > > > http://rapidshare.com/files/52236170/example.tif.html > > > > (Note please that the file has the size of 18MB.) > > > > Paul > > > > > > > > > > > On 8/29/07, Paul Smith <[EMAIL PROTECTED]> wrote: > > > > > > > > Dear All, > > > > > > > > I have got a colored scanned TIFF image from a newspaper article. Can > > > > ImageMagick be used to convert the color of the image background to > > > > white, with no loss? > > > > > > > > Thanks in advance, > > > > > > > > Paul > > > > _______________________________________________ > > > > Magick-users mailing list > > > > [email protected] > > > > > > > > http://studio.imagemagick.org/mailman/listinfo/magick-users > > > > > > > > > > > > _______________________________________________ > > Magick-users mailing list > > [email protected] > > > http://studio.imagemagick.org/mailman/listinfo/magick-users > > > > _______________________________________________ Magick-users mailing list [email protected] http://studio.imagemagick.org/mailman/listinfo/magick-users
