filter

Color Spotter

juef — Thu, 17 Sep 2009 04:22:11 +0200

What is Color Spotter? Basically, it's contrast, but "centered" around a color. Another way to see it is as another "Color selection" tool: you specify an image, a kind of threshold, and it selects color that are close to the one you specified; only, Color Spotter keeps every pixel from the image, darkening the wanted colors, brightening the others.

The best way to understand is to see it in action:

Here, the selected color was from a pixel from the plantpot (beige-ish).

This plug-in was mostly an experiment for me: you could say I made it just to get familiar with programming C plug-ins in GIMP. I have another plug-in I want to make, but as it's much more complicated, I wanted to make sure I could deal with the basics first.

Suggestions welcome! Thanks for reading, hopefully this will be useful to at least one person :)

Sharpening

Redphoenix — Tue, 07 Jul 2009 19:20:35 +0200

This script sharpens an image using some simpel layer manipulations. It offers a Radius and a strength operator to increase strength vs quality. I also added a simpel brightness correction in order to remove highlights created by a too high sharpening value. IT's therefore recommended to increase the correction value when increasing the strength value a lot.

Tileable Filters

RobA — Thu, 19 Feb 2009 22:56:23 +0100

I have created a wrapper script to allow a number of existing filters to have tileable results (assuming the input layer is tilable).
This script creates the following new menu entries (modeled after the Tileable Blur provided in Gimp already):
Filters >Distorts >Tileable Emboss
Filters >Blur >Tileable Motion Blur
Filters >Distorts >Tileable Wind
Filters >Light and Shadow >Tileable Sparkle
Filters >Noise >Tileable Slur
Filters >Noise >Tileable Spread
Filters >Artistic >Tileable Cubism
Filters >Artistic >Tileable Oilify
Filters >Artistic >Tileable Photocopy
Filters >Artistic >Tileable Softglow

More can be added, I just went through the menus looking for ones that could benefit from this.

Here is an example of the stock wind filter and with the tileable wrapper.

-Rob A>

G'MIC plug-in

dtschump — Tue, 13 Jan 2009 14:16:31 +0100

The G'MIC plug-in for GIMP defines a set of various filters, including artistic filters, image denoising and enhancement, 3D renderers, etc.. It is a quite large plug-in, integrating a lot of different effects to apply.

This plug-in is able to update his list of filter definitions from the Internet (so it improves itself over time), as well as allows any user to add its own custom filters in it.
It has been written by the author of the GREYCstoration algorithm (used for image denoising). It is actually intended to replace it in a near future.

Download G'MIC for Windows 32 bits

Here is one screenshot of the plug-in in action, as well as a result of filter application :

msx1 filter

nitrofurano — Fri, 01 Aug 2008 19:59:44 +0200

The code still have some accuracy bugs when compaired with its sdlBasic version, since i were getting some problems when recoding it to Python-Gimp.
The script converts a rgb picture into msx1 (also colecovision and sega sg1000) display limitations, which have a predefined palette, and a maximum of 2 colours in each 8x1 pixels cell, trying to provide this cell as the most close as possible from their rgb original.
As well, the code is a bit slow (a 320x240 picture can take around 1 minute on a 2ghz dualcore computer) since it processes pixel by pixel.
I'm posting here the code anyway hoping i can fix it soon, or someone could help on it...

High Pass FIlter

RobA — Fri, 25 Jul 2008 16:59:51 +0200

A general purpose high-pass filter plugin. It shows up as Filters->Generic->High Pass Filter. You can select a blur radius that sets the size of detail to be passed by the filter, a contrast adjustment, as well as an option to keep the source layer or replace it.

It actually implements 5 different high pass modes:

Colour - I think this is the same as photoshop's high pass filter effect.
Preserve DC - like colour, but adds the average image colour back in.
Greyscale - this desaturates the layer before high pass filtering.
Greyscale, Apply Chroma - as above, but blends it in with the source layer colours
Redrobes - (named after the technique described by Redrobes)

They are all straightforward, using the basic "duplicate, blur, invert, 50% opacity, merge down" process, with a few small details added for each, except the Redrobes mode. The steps he described were:

Get an image 1.

Blur it quite a lot 2.

Blur it until its a constant colour 3.

Use Image arithmetic to generate 2 - 3 => 4

Use Image arithmetic to generate 3 - 2 => 5

Take 1 and subtract 4 and add 5 => 6

While this is supposed to be the same as a basic filter with preserve DC offset, it seems to give slightly different results, so I left it in :)

For more details and sample images, see my blog post:
http://ffaat.pointclark.net/blog/archives/152-High-Pass-Filter-Plugin.ht...

Urban Acid

tuxcomputers — Sun, 08 Jun 2008 22:36:50 +0200

This script simulates the colour effect you get when you cross process a film.

Before:

After:

Soft focus

tuxcomputers — Sat, 31 May 2008 00:00:00 +0200

This script simulates the effect of a soft focus.

Before:

After:

A tutorial on how to use this is coming soon.

Shadows&Highlight

steelneck — Sun, 27 Apr 2008 23:24:20 +0200

This Shadow&Highlight script does a decent job of lightening shadows and/or darken highlights in photographs. The UI gives you five control sliders. Two for control of the Shadow and Highlight amount (opacity), two for the tonal width of each contrast mask layer (using gamma), and one for the blur radius of the masks. Plus the option to flatten visible layers when done.

A note on the tonal width sliders, the Shadow Tonal width works as expected giving a wider/heavier tonal range using higher value. But the Highlight Tonal width behaves opposite, affecting a smaller tonal range using higher values.

Deskew

quarl — Mon, 07 Apr 2008 13:24:55 +0200

Deskew, also called auto straighten, is the automatic rotation of an image such that the text is vertically aligned. This is great for cleaning up scanned documents.

http://www.cubewano.org/gimp-deskew-plugin/