Gimp Traffic #30 For 5 Feb 2001

By Cris Flagg

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Table Of Contents


The stats are missing information for the number of contributors this week.

Mailing List Stats For This Week

We looked at 22 posts in 45K.

There were 1 different contributors. 1 posted more than once. 1 posted last week too.

The top posters of the week were:

1. Bug With 'Make Uninstall'

25 Jan 2001 (1 post) Archive Link: "Bug with make uninstall"

People: Uwe Koloska

Uwe Koloska reported a bug with "make uninstall" in version 1.2.0 and earlier "
I have no Parse::RecDescent and therefore scm2perl will not work and not be installed.

When uninstalling, make tries to unlink scm2perl
unlink /usr/bin/scm2perl
Cannot forceunlink /usr/bin/scm2perl: No such file or directory at -e line 1 and stops
make: *** [uninstall-recursive] Error 1"

Uwe suggested "make -k uninstall" as a workaround, but tought the actual fix should be left to the experts.

2. Bumpmap With Negative Depth

25 Jan 2001 - 31 Jan 2001 (16 posts) Archive Link: "Bumpmap with negative Depth ??"

People: Federico Mena QuinteroRebecca J. WalterSteinar H. GundersonJens LautenbacherGarry R. OsgoodTom Bech

Lasm posted a question related to the use of an engraving plugin v. an embossing plugin. Tal Danzig reported that the "reverse" option on emboss was the answer and to play around with the azmuth. Lasm replied that the "Invert Bumpmap" option worked like azimuth, rotating the light source 180 degrees. The desired effect is to create a sinking crater rather than a raised emboss. Lasm mentioned a Photoshop layer effect that had the desired effect. Jens Lautenbacher said the impression of height in a bump map was achieved by the gradient, so inverting the bumpmap was a means to change the gradient. He agreed that a layer mode would be nice, but thought that the "Invert Bumpmap" functioned properly. Rebecca J. Walter suggested making it a layer operation by duplicating and inverting the bumpmap layer and using the duplicate for the bump mapping. Jens again pointed out that this is exactly what the "Invert" button did in the bump map plug in.

Lasm saw the point about inverting the bump map, but was still not satisfied with the resulting image. Lasm said " the PS Lighting effects did it more "politically correct". If you press the "inverse bumpmap" there, the effect is different from the "Invert" Bump Map in Gimp" Federico Mena Quintero explained that " The Bumpmap plug-in works by taking the intensity values to be height values and computing the surface normal at each point. Then it does simple Gouraud-like shading on the destination image. Inverting the bumpmap source is exactly the same as using the "invert" button on the plug-in's dialog box; the intensity values are inverted and the surface normals will point in the opposite direction." He added that the reason Photoshop produced different results was the use of Phong shading, which can be achieved in Gimp what Tom Bech's plugin.

Garry R. Osgood provided a good explanation of why inverting the gradient and rotating the light source had the same effect. Not knowing the settings used to create a particular image of a conical hill, one person can perceive it as a raised conical hill and another as the rim of a conical depression. This is due to the fact that "light" is, in this case, simply the first derivative of the altitude map. Lasm thanked Garry for his explanation, and asked if the algorithm could be supplied with negative as well as positive integers. Jens Lautenbacher again pointed out that this was "Inverting" the bumpmap and had laready been covered.

Steinar H. Gunderson asked if it mattered whether 255-bm or plain -bm were used. Federico Mena Quintero said that this would change nothing since it was the surface normals that were computed.

The thread ended without Jens having to explain "Invert Bumpmap" again.

3. gimp-print 4.1.3

29 Jan 2001 (1 post) Archive Link: "ANNOUNCE: gimp-print 4.1.3"

People: Robert L Krawitz

Robert L Krawitz announced gimp-print 4.1.3

Gimp-Print 4.1.3 is a development release in the 4.1 line. This version marks a complete reorganization of the source tree. Gimp-Print now uses the GNU build tools much more comprehensively in the past. It builds a single shared library that the Gimp plugin and the CUPS driver (and perhaps other future applications) can link against.

This new architecture will make for a much better system, but this particular release is more likely to be unstable than most due to the rather radical change in architecture.

Gimp-Print 4.1.3 contains the following fixes and improvements over 4.1.2:
  1. The source has been completely reorganized. Please read the README file for more information!
  2. Improvements to the Lexmark driver.

4. Realistic Media Plug-In For The GIMP v1.2

30 Jan 2001 - 1 Feb 2001 (3 posts) Archive Link: "ANNOUNCE: Realistic media plug-in for the GIMP v1.2"

People: David A. BartoldRebecca J. Walter

David A. Bartold announced a new plug-in.

I am pleased to announce a new plug-in that provides GIMP users with a realistic color pencil tool. Given a pressure-sensitive graphics tablet, it looks and feels like a real artist's pencil. You can also use a mouse if you'd like. The plug-in provides two new menu items: Image/Media/Texture... and Image/Media/Color Pencils.... The "Texture" item will let you select from a few common paper textures and then generates a texture channel for your image. You can also generate your own textures using the standard GIMP tools/filters. The "Color Pencils" item will pop up a new window that will let you draw and erase as desired. Once you have the image the way you want, you can hit the "OK" button and the image will be updated in The GIMP.

David also pointed to ( as the location of the source code and the web site.

Rebecca J. Walter thought it looked "pretty cool" and wanted to know if there was full control over the color. David replied that that was one of the fist things he wanted to add. He said there was a color display located on the web site as phymodmedia-0.4.1.tgz.







Sharon And Joy

Kernel Traffic is grateful to be developed on a computer donated by Professor Greg Benson and Professor Allan Cruse in the Department of Computer Science at the University of San Francisco. This is the same department that invented FlashMob Computing. Kernel Traffic is hosted by the generous folks at All pages on this site are copyright their original authors, and distributed under the terms of the GNU General Public License version 2.0.