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Plug-ins; description and function

In this and following chapters we'll take a walk down the Filters menu, and see what kind of goodies are hidden there.

Plug-ins

When an ordinary Photoshop user thinks of plug-ins, things like Eye Candy and Kai's power tools comes to his or her mind. Gimp plug-ins does the same; they permit the user to add extra features into Gimp. With features, we mean filters, printer drivers, mail interfaces, save/write modules etc. This is also true for Photoshop and similar Windows programs. As far as I know, the Gimp is highly modularized, so nearly every function beside basic Gimp stuff has to be done by plug-ins.

Many Gimp users/developers have made Gimp plug-ins, which are available to the Gimp community. We encourage you to do the same. If you have made your own plug-in, submit it to the Gimp community under GPL licence! It will make Gimp even greater.

In this chapter, we will discuss the filters menu, and we will call these filters plug-ins, because that's whats most people think of when the hear the word plug-in. The Script-Fu sub-menu is included because these Script-Fu's can be applied as ordinary filters to your image. You'll find that you can make your own plug-ins quite easily, without expert knowledge of C programming and GTK libraries.

Since plug-ins and Script are rapidly developed in the Gimp community we at Frozenriver can't keep this chapter as updated as we would like to do. We would like to make an update every second week or so. We also encourage developers to send us a mail about their new or changed "plugin" so we have a easier job updating this chapter. In appendix X you'll find some tips on how to compile plug-ins. When we use the term "image" we mean (most of the time) both image and drawable.

In this chapter we'lll use the same pictures when we want to show the result of the plug-in. Two colored ones and a grayscale..

The main categories

In the filter menu you'll find the following sub-menus, which also groups the plug-ins by what they are capable of doing.

• Artistic: Here you'll find filters that creates instant artistic effects in your image. You can get stuff like cubism, mosaic etc. You will mainly use this kind of effects in an image, but you can also create nice patterns and many other things. Just to use your mind and imagination, and there is no end to what you can achieve.
• Blur: Includes different kinds of blur filters. Blur can be useful when you want to soften a part of picture. Shadows are seldom hard and opaque, you'll want to soften all created shadow areas with blur. A portrait may look too honest and show all the skin imperfections and wrinkles of the model - then blur comes in handy. (This trick is used all the time in modeling magazines, that's why they always look so perfect. (But if your model is ugly, blur can't do anything about it.)
• Darkroom: Here you'll find a tool that makes your images look like film, and another that lets you manipulate the picture's color and HSV values, just as if you was standing in a darkroom.
• Distorts: All kind of tools that will distort your image, displace, noise, shift, waves etc. Some of these filters are nice if you want to make your image look artistic. Maybe you want to create textures. If so, some of these filters can be very useful to you.
• Edge detect: These tools lets you detect the image's edges (light to dark, one color to another) in different ways. It can be quite useful when you work with a layered image, and you want to highlight the edges. You can also use it for making easy selections with the magic wand. This makes selection a lot easier than with the Bezier tool, but it's no final solution. You will have to experiment to find all the functions and working areas of these plug-ins.
• Effects: Effects is similar to distort. "Effects" will also alter your image, but in a more obvious way, like the Super Nova for example, which will add a nova star to your image.
• Image: The image plug-ins will enhance or de-enhance your image in different ways. These filters are good for retouching poor images, or they can add special effects, like making your image to look old for example.
• Render: Will render a figure which can be a god start for textures, or you can use them for creating patterns, or as a beginning of a background, or......
• Textures: Will make textures for you, but they can of course be used for other things as well.
• Transforms: Transforming filters like rotate and tileit.

There are also some shortcuts like "Shift+Alt+F" which brings up the last plug-in you used (if you haven't reassigned the shortcut). "Alt+F" will apply your last used filter once again.

Animation

Animation playback

This plug-in will play back your layers or Gif animation. If the image isn't a gif, it will playback each layer in Combine mode. You can also step each frame.

Gif animation: (not a plug-in)

If you want to make a Gif animation, Gimp is the ultimate tool.

Gimp treats each layer as a frame. The Background layer is Frame 1. and each new layer will be a new frame. When you add a new layer to the background layer, name it Frame 2, Frame 3 and so on. You can also specify the delay of each frame.

The way to do it is: Edit the layer name and rename it "Frame X (xxxxms)" where X is your frame number and "xxxx " is your delay in milli seconds "Frame 5 (100ms)" will give that frame a delay of 100 ms.

To make each layer Combine (Combine means that Frame 2 will be added to Frame 1 (the background), Frame 3 will be added to Frame 2 and Frame 1, and so on), just name the layer "Frame X (xxxxms) (combine)".

To make it like in a real movie, i.e. each frame will replace each other, just add (replace) instead of (combine). When saving your gif, don't ever check "Don't care" because it will make the layers combine, and that combine will not show up in the Gimp layer dialog as (combine). You can combinate (combine) and (replace) in any order.

An example:

" Background (100ms) (combine)", "Frame 2 (100ms) (replace)", "Frame 3 (100ms) (replace)", "Frame 4 (100ms) (combine)", "Frame 5 (100ms) (replace)"

will be played like this:

"Background", "Background + Frame 2", "Frame 3", "Frame 4", "Frame 4 + Frame 5", all with 100ms delay.

Artistic Plug-ins

Cubism

Allows you to make cubist art of your image. If you check " Use background color" you will get the background color between your tiles, unchecked will get you black. Tile size is how cubistic you want your image to be, higher values result in a more cubistic image. The saturation value decides how colorful the image will be. A tip is to use cubism in several layers, with different modes over the original image to achieve special effects.

Mosaic

With this plug-in you can imitate everything from a glass painting to a cheramic mosaic. This plug-in has many parameters that lets you control the final result; size and height of the tiles, the spacing between them, and the neatness which controls what the stones will look like. If you use a hexagon shape, the stones will be hexagonic with a high neatness value If you lower the neatness value, the hexagonic structure will fade out, and the stones will look more like the natural stones you find in nature. Light direction controls in what way the daylight will appear to shine on the mosaic edges. Color variation adjusts how much the color is allowed to variate. With a low value, the original color from the image will be preserved. Titeling primitives is what kind of mosaic tiles (stone structure) you want as base for your mosaic. If you set a low neatness value and a high value of color variation, you will get a very abstract mosaic. Antaliasing will get you smooth edges on the mosaic. Color Averaging will get you a real mosaic. If this option is unchecked the original picture will only get a mosaic texture. Pitted Surfaces will get you a surface that will look old and used. FG/BG controls what kind of color edges you want. If unchecked, it will use the foreground from the toolbox, BG will use the background color from the toolbox.

Mosaic is a nice tool for creating interesting surfaces. You can easily take a stone pattern and combine it with mosaic to get an old stone floor to use in your image, or you can get a cracked glass/windshield, or....

Oilify

As you might guess, it will make a oil painting out of your image. The mask size will sets the outcome. A high value makes the image less detailed and simplyfied. This tool is also nice to use with layers, or you can use it to make selections of object that otherwise would be difficult to select.

Sparkle

With this tool you can create sparkles, or get a frosty, diamond feeling to your object. To use it effectively, try it in a small selection first,and you will have more control over where the sparkle will end up. You can also use a transparent layer where you put tiny white spots, the sparkles appear where the spots are. Why? Sparkle will choose the brightest point in your picture and put a sparkle there. This behavior makes it very hard to predict where the sparkles will go. The luminance parameter controls how many sparkles you want. A low value will produce sparkles only at very bright parts of your image. Flare Intensity refer to the light intensity of your star. Spike length controls how long the star spikes will be. Spike points tells you how many spikes you will get - 1 spike point will get you 2 spikes, 2 will get you 4 spikes and so on. Spike angle is the angle of the ground spike (1 spike point) and if it's set to zero you will get a horizontal spike, 90 will get you a vertical one and so on.

Van Gogh (LIC)