discrete color scale bitmap becomes continuous object after eps/pdf export

Bug #1174651 reported by smu on 2013-04-30
This bug affects 1 person
Affects Status Importance Assigned to Milestone

Bug Description

I have a figure created with ncl[1] that I would like to modify using inkscape. When I import the file in inkscape everything looks fine, but after exporting to eps or pdf, the discrete color label bar becomes a continuous color scale.

Here is the inkscape svg file


This is the exported eps:


The color scale was extracted from this pdf:


According to a discussion on inkscape-users [2] it may be that inkscape interprets the size of the color scale object in a wrong way.

inkscape version is 0.48.4 on arch linux.


[1] http://www.ncl.ucar.edu/
[2] http://sourceforge.net/mailarchive/forum.php?thread_name=1367277257508-4966775.post%40n6.nabble.com&forum_name=inkscape-user

jazzynico (jazzynico) on 2013-04-30
tags: added: color eps exporting pdf
su_v (suv-lp) wrote :

It seems to me that Inkscape's cairo-based export is correctly interpreting the SVG data based on the SVG specification:

If adding the missing attribute mentioned in bug #616717 to the <image> element, the scaled bitmap image renders equally as continuous color scale in other SVG viewers (Batik, Firefox, Opera, librsvg) as it appears in cairo-based exports from Inkscape (PDF as well as PostScript).

Inkscape's current trunk though renders the scaled bitmap rather blurry towards all edges (unlike other SVG viewers).

Related earlier reports:
- Bug #461467 in Inkscape: “Image scale saved incorrectly”
- Bug #616717 “Resized bitmap images are rendered differently by Firefox or Batik ('preserveAspectRatio' attribute not set)”
- Bug #1163449 “Imported bitmap appear blurry when zoomed in”
(new rendering of scaled bitmap images in current Inkscape trunk: it appears that Inkscape's pixelized view of up-scaled / zoomed-in bitmap images (old renderer in stable versions, trunk <= r12227) does not conform to the current SVG 1.1 specification, and that the spec currently does lack a solution supported by Inkscape to produce the same view as produced by Inkscape's old renderer in current stable versions)

su_v (suv-lp) wrote :

Disucssion on 'inkscape-devel' related to rendering of up-scaled bitmap images:

su_v (suv-lp) wrote :

Various screenshots (SVG: librsvg 2.36.3, Squiggle (Batik 1.7), Opera 12; EPS: evince 2.30.3, cairo 1.12.2)

smu (smu) wrote :

I tried to reproduce the results using an older version of inkscape.
With inkscape 0.47 on debian squezze I get a discrete color scape in the eps.

Jaspervdg (jaspervdg) wrote :

There is no one correct way to interpolate a bitmap, and SVG lacks a way of defining what interpolation to use. (As mentioned above, we recently had a discussion on this subject.) PDF apparently does have a switch to control interpolation to some degree (I am not sure about eps, but it might have one as well), so if Inkscape did have a way to at least switch between "blocky" and "smooth", then we could look into making sure that this gets transferred correctly to/from pdf (and possibly eps). In that light I would consider this report to essentially constitute a feature request (one that at the moment, unfortunately, cannot be adressed just yet).

su_v (suv-lp) on 2013-05-01
Changed in inkscape:
importance: Undecided → Wishlist
status: New → Confirmed

On 2013-05-01 10:03 (+0200), Jaspervdg wrote:
> if Inkscape did have a way to at least switch between "blocky" and
> "smooth", (...)

Implemented in Inkscape 0.91 (on import, and changeable later on via
Object properties dialog).

> (...) then we could look into making sure that this gets transferred
> correctly to/from pdf

Export: supported with Inkscape 0.91 r13725
(see attached examples: SVG, PDF, screenshot Evince)

Import: Implemented for upcoming 0.92, see revision 14171:
* Respect PDF image 'interpolate' value on import.

Changed in inkscape:
milestone: none → 0.92
status: Confirmed → Fix Committed
Bryce Harrington (bryce) on 2017-01-10
Changed in inkscape:
status: Fix Committed → Fix Released
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