Forum: Inkscape discrete color scale object becomes continuous in eps export

96544a195c496cecd6bf313bf69d3f93?d=identicon&s=25 unknown (Guest)
on 2013-04-29 21:21
(Received via mailing list)
dear all,

I have a inkscape problem that I do not understand. An object
showing a discrete color scale is converted to a continuous scale in the
eps export.

here is the example file
http://www.climate.unibe.ch/~muthers/exchange/drawing.svg

this is the exported file
http://www.climate.unibe.ch/~muthers/exchange/drawing.eps

any help is appreciated!

inkscape version is 0.48.4 on arch linux.

cheers,
 stefan
A5d6523ccc839b167600bb7d52067815?d=identicon&s=25 alvinpenner (Guest)
on 2013-04-29 21:55
(Received via mailing list)
I don't know much about bitmaps, so you may get a better answer from
someone
else, however here are a few comments. The problem appears to be related
to
the fact that this was originally an embedded png image. The size of the
image was 1 pixel by 1 pixel. This is shown in the svg tag

      <image width="1"   height="1"  transform="matrix(1,0,0,-1,0,1)"
xlink:href="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAA4AAAABCAYAAADuHp8EAAAABHNCSVQICAgIfAhkiAAAAERJREFUCJkBOQDG/wG2aij/FxsXABQgJQAUKCAAABMaAAoVHAAACkUAAAAAAM4AzgDM8eUAus3tABvtKQCXxugA/cioAGJcEJMX3vuCAAAAAElFTkSuQmCC"
         id="image20862" />

Then the image was expanded by a factor of 465 horizontally and 25
vertically. This is shown in the element
      transform="matrix(465.32309,0,0,25.338759,163.05532,330.72791)"

During this expansion, Inkscape chose to interpret the color gradations
in a
discrete way as 14 separate colors, while the postscript file apparently
interpreted these as a continuous color scale. I think the Inkscape
interpretation is probably the correct one; however, the way to avoid
this
in the future would be to import a full size png image that does not
need to
be scaled.

cheers,
Alvin Penner



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96544a195c496cecd6bf313bf69d3f93?d=identicon&s=25 unknown (Guest)
on 2013-04-29 23:02
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hi Alvin,

thank you for your comprehensive explanation!

The color scale stems from a PDF file produced with ncl[1]:

http://www.climate.unibe.ch/~muthers/exchange/nclplot.pdf

I tried several PDF viewers, in any case the color scale was displayed
in the correct way. Therefore I would expect the same after importing
(File->Import) and exporting it (to eps or pdf) using inkscape.

It this maybe a inkscape bug?

As a workaround I found that I can export the color scale as bitmap and
then re-import it into inkscape. After this, the exported eps looks the
way I expect it to be.


cheers,
 stefan

[1] http://www.ncl.ucar.edu/
A5d6523ccc839b167600bb7d52067815?d=identicon&s=25 alvinpenner (Guest)
on 2013-04-30 01:15
(Received via mailing list)
yes, it looks as if this is probably an Inkscape bug. I loaded the file
nclplot.pdf into Inkscape and got the same result as you got, namely an
image of size 1 pixel by 1 pixel.
Then, just for curiosity, I used Ghostscript to do a direct conversion
from
.pdf to .ps without using Inkscape at all. The command I used was:
pdf2ps nclplot.pdf ncltest.ps
This gave me the attached .ps file, which appears to be identical to the
original pdf file. ncltest.ps
<http://inkscape.13.x6.nabble.com/file/n4966775/ncl...
So it is likely that the conversion error was caused by scaling
performed by
Inkscape.

Alvin



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96544a195c496cecd6bf313bf69d3f93?d=identicon&s=25 unknown (Guest)
on 2013-04-30 11:27
(Received via mailing list)
On Mon, Apr 29, 2013 at 04:14:17PM -0700, alvinpenner wrote:
> yes, it looks as if this is probably an Inkscape bug.

I reported this as a bug, lets see what happens.

https://bugs.launchpad.net/bugs/1174651

cheers and thanks again,
 stefan
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