On 03/20/2013 07:08 PM, sonicbluegt wrote:

Windows 7 64 home
Gimp 2.8.4

Import .svg file into gimp.. Image size 1024x1024 and smaller produces aliasing. Any ideas?

Using the Import dialog to increase the size of the output image in pixels - doubling it or more - greatly reduces "normal" aliasing during the rendering process. That's the "scalable" part of "Scalable Vector Graphics" at work.

Sometimes it makes sense to export an SVG image as PNG from Inkscape, and import the PNG into your GIMP XCF file in progress.

If you are seeing an abnormally large amount of aliasing I don't know what might be causing that - but the above methods might help.

:o)

Steve

Date: Thu, 21 Mar 2013 12:11:44 +0100 From: forums@gimpusers.com
To: gimp-user-list@gnome.org
CC: team@gimpusers.com
Subject: [Gimp-user] aliasing in vector images

Thanks for the reply Steve!

I think maybe my problem wasn't communicated from my end correctly.

I have an SVG file generated with a native resolution of 2048x2048 in Vector Magic. In Inkscape, I can resize the image to be 1024x1024, zoom in, and it "redraws" the image with no aliasing (as a vector should).

You
mean that in GIMP's vector import dialog you specify a scaling ratio (X Ratio / Y Ratio) of 0.50 ? Then of course you are going to get some aliasing (just the same as if you scaled a raster image by 50%), but the overall result should closely resemble what the original SVG document looked like . . . at a 50% zoom level.

Remember that in a vector document "pixels" do not correspond to "on-screen" pixels but are a physical unit of measure.

The biggest red flag that led me to believe something wasn't working correctly was when opening a vector in GIMP at a size of about 80x50 and all it produced was an unrecognizable blob of pixels. I feel as though I've been able to do this in the past and it would produce a smooth image without aliasing.

If you are taking the 2048x2048 image and scaling it to 80x50 then that is a ratio of less than 10 percent and of course the result is probably going to look like a blurred/aliased mess of pixels. Now if the original SVG document itself had a document size of 80x50 (which is separate from the size of vector elements in it) then GIMP should be able to import it fine.

-- Stratadrake strata_ranger@hotmail.com
--------------------
Numbers may not lie, but neither do they tell the whole truth. =

On 21-Mar-13 12:11, sonicbluegt wrote:

What I'm trying to do is overlay a design onto another image without aliasing. What I'm ending up with, though, is no better (actually might be worse) than just drawing the image in GIMP instead of importing a vectored version of the same graphic.

Why don't do this in Inkscape?
You can import an image and use it as backdrop. Then export everything as jpeg or whatever.
Hope it helps
mario

Ing. Mario Valle
Swiss National Supercomputing Centre (CSCS) | http://mariovalle.name/
v. Trevano 131, 6900 Lugano, Switzerland    | Tel: +41 (91) 610.82.60

On Thu, 2013-03-21 at 12:11 +0100, sonicbluegt wrote:

[...]In Inkscape, I can resize the image to be 1024x1024, zoom in, and it "redraws" the image with no aliasing (as a vector should).

However, when I do the same in GIMP, it aliases, as though it's no longer a vector and is drawn as a raster image instead. I understand that GIMP is raster-based. I guess I was just thinking that when it "opens" a vector image, that it's still in vector format instead of being rasterized.

No, it's rasterized. You can import SVG as paths if that helps.

Is it possible I'm missing a plugin or something since I updated GIMP? Would installing Ghostscript or GFig on my machine solve my problem? Or is it possible that nothings wrong and I'm trying to do something that's just not capable?

Rasterizing is normal behaviour. Opening SVG in GIMP at a high resolution helps a little. I don't recommend using GFig, and I don't think it can do SVG (when it can do anything at all).

Liam

Liam Quin - XML Activity Lead, W3C, http://www.w3.org/People/Quin/
Pictures from old books: http://fromoldbooks.org/
Ankh: irc.sorcery.net irc.gnome.org freenode/#xml

On 21-Mar-13 19:28, sonicbluegt wrote:

Thanks everyone for the help!

Why don't do this in Inkscape?
You can import an image and use it as backdrop. Then export everything as jpeg or whatever.
Hope it helps
mario

I may give this a shot. If I can export as a TGA file from Inkscape, then I'll definitely be doing it this way.
Thanks!

No, Inkscape exports only png. But if you install imagemagick you can convert easily:

convert yourimage.png yourimage.tga

Or import in GIMP and export as TGA.

Hope it helps mario

Ing. Mario Valle
Swiss National Supercomputing Centre (CSCS) | http://mariovalle.name/
v. Trevano 131, 6900 Lugano, Switzerland    | Tel: +41 (91) 610.82.60