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List:       koffice-devel
Subject:    Re: The road goes ever on
From:       Vadim Plessky <lucy-ples () mtu-net ! ru>
Date:       2002-10-30 7:42:58
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On Tuesday 29 October 2002 10:00 pm, Dirk Schönberger wrote:
|  > Let's take, for example, high-quality and small in size image (attached,
|  > web-spider-rsvg.png). It is 23K.  I generated it using librsvg-2.1.1,
|  > from SVG file (4.4K, it is also attached).
|  >
|  > I have tried several paths to convert this image to PS (EPS is PS with
|  > bounding box).
|  >
|  > 1) First I converetd it using latets stable release of Imagemagick
|  (5.5.1):
|  > .....
|
|  Ouch. I think I understand what you did, but I still don't think it is the
|  right tool for the job.
|  The idea behind what you did is using EPS as some kind of "container" for
|  the actual image / bitmap data. This is possible, but it should only used
|  for outputting to a real Postscript printer. You don't convert the image
|  data to vector data, but instead convert the image data from its
| compressed form as PNG to an uncompressed form which is uncompressed form
| useable by a printer.

You haven't mentioned that you want to convert image to *vector format*!

|
|  This way is also done by the other tools you mentioned.
|
|  For conversion to vector data you need more specialized tools, like e.g.
|  Adobe Streamline or something like the Open Source "autotrace" project
|  (somewhere on sourceforge, IIRC.

Yes, there is an Open-Source autotrace, which also can be used by ImageMagick, 
BTW (if it is installed).
But do you really wnat to *autotrace* PNG or JPEG, during export to Latex?..

Anyway, there is a way to have automatic ratser->vector "losssless" 
conversion. But this would produce *huge* output files!

You take your image, and convert  *each pixel* to rectangle, than position 
each pixel one after another.
Rectangle would have default RGB value of that pixle as 'fill', and no border 
(stroke:none).
For the reference image which I used this would produce:
160x160=25600 rectangles.
It would be interesting to see png2svg utility doing this job. 
(which would greatly complement Karbon14' set of tool, IMO)
I guess 'rect' primitive is ok for this task, no need to use 'path'

Such approach even would allow scaling for those pseudo-vector images.
If you use scaling factor of 3X, you need just to replace solid fill with 
linear gradient, and you will get smoothing/scaling working for raster 
imeges!
// high-end PS interpreter does scaling of images exactly in such way, BTW.

|
|  > |  I don't think Ghostscript is the right tool for this job, because its
|  main
|  > |  goal is mostly reversed, i.e. the conversion of vector data /
|  Postscript
|  > |  calls to a rendered image.
|  >
|  > GS is not "right tool" for any task, but until we have couple of good
|  > SVG renders compliant with SVG 1.1, and QT patched to produce SVG
|  > instead of
|  PS
|  > (WSVGprinter class), we need to "live with GS".
|
|  What do you want to achieve? From what I understand, SVG is more suited to
|  "clip art", i.e. one page, or a small area thereof, similar to EPS. Real
|  Postscript files mostly contain multiple pages.

Com'on, SVG is XML-based.
You always can have a wrapper around several SVG images, in XML format.
The easiets way to achieve this is to use XHTML+CSS, or XML+CSS, with paged 
media (@media page)

|  I think Karbon14 contains a nice substitute for a SVGPrinter class, but
| this implies using Karbon's VPainter API instead of QPainter.

Yes, Karbon14's progress is very impressive!

|  >
|  > Forget about Qt for Vector graphics.
|  > AFAIK Qt is limited by QPainter, so you can't expect from QT something
|  which
|  > exceeds its capabilities.
|  > That's why there is a KSVG, while Qt3 has support for (rudimentary in
|  > complexity) SVG files.
|  > This question has been asked, and Trolls answered that they are not
|  > going
|  to
|  > provide reference SVG implemenattion inside QT3.
|
|  Again, I think Karbon provides a nice rendering model similar to
| Postscript / PDF and SVG. The problem is, that the Karbon developers have
| not enough free resources to use the VPainter API outside of the actual
| Karbon. Please feel free to evaluate the API and nag the Karbon developers,
| like Rob Buis, for feature enhancements. Please be prepared to get told "do
| it yourself :)"

Thanks, I send bug reports to Rob already for some time! :-)

|
|  Regards
|  Dirk
|  _______________________________________________
|  koffice-devel mailing list
|  koffice-devel@mail.kde.org
|  http://mail.kde.org/mailman/listinfo/koffice-devel

-- 

Vadim Plessky
http://kde2.newmail.ru  (English)
33 Window Decorations and 6 Widget Styles for KDE
http://kde2.newmail.ru/kde_themes.html
KDE mini-Themes
http://kde2.newmail.ru/themes/

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