# Filters

This chapter describes the various filters in detail. To illustrate the result of applying the filters, each description is accompanied by an sample image with the respective filter applied to it. The original image (with thanks to the photographer, Christian Peper) is shown below at half of the original size. The sample images demonstrating the results of applying the filters, are shown at 25% of the original size.

Some filters yield reasonable results for most images. For other filters though, quite some tweaking needs to be done before the desired outcome is achieved. If a filter does not do what you want, it might need more or less customising.

See the Dialogs chapter for more information on the dialog windows containing the filter settings.

The original image.
The original image.

The original image.

## The Bumpmap filter

The Bumpmap filter takes two layers and uses one of these to convert the other one so that it will give an illusion of depth. The object layer (the layer to be transformed) is the actual layer that should receive the three-dimensional looks. The bumpmap layer is a grayscale layer, which is read and used to determine the height for each point of the object layer.

Alternatively, the same layer can be used as both object layer and bumpmap layer.

The image with the Bumpmap filter applied to it.
The image with the Bumpmap filter applied to it.

The image with the Bumpmap filter applied to it.

## The Edge Detection filters

These filters try to detect edges (boundaries) in the picture and modify the image such that only these edges retain their respective colors, while the rest of the image is turned gray. Through the use of lighting the image will then get a three-dimensional look.

There are four edge detection filters available. Each of these detects edges from a different side (possibly considering other parts of the image as being edges) and will therefore obtain a different resulting image.

The image with the Bottom Edge Detection filter applied to it.
The image with the Bottom Edge Detection filter applied to it.

The image with the Bottom Edge Detection filter applied to it.

## The Emboss filters

Emboss filters work somewhat like edge detection filters, with the difference that embossed images are entirely gray. Areas in the picture are detected and are given a certain height level, which is made visible by using grayscale borders, making the image look like it is three-dimensional.

The image with the Emboss All filter applied to it.
The image with the Emboss All filter applied to it.

The image with the Emboss All filter applied to it.

The image with the Emboss Variable filter applied to it.
The image with the Emboss Variable filter applied to it.

The image with the Emboss Variable filter applied to it.

## The Gaussian Blur filter

This filter makes the image a little fuzzy by blurring it in a pseudo-random way. A gaussian algorithm is used for finding the extent to which each part of the image should be blurred.

The image with the Gaussian Blur filter applied to it.
The image with the Gaussian Blur filter applied to it.

The image with the Gaussian Blur filter applied to it.

## The Invert filter

This filter inverts all colors. The Red, Green and Blue component of each pixel are taken and subtracted from 255. This means that red becomes cyan, green becomes purple, and blue becomes yellow. The resulting values form the new pixel color.

The image with the Invert filter applied to it.
The image with the Invert filter applied to it.

The image with the Invert filter applied to it.

## The Mean Removal filter

This filter sharpens the image by changing the colors of neighboring pixels with approximately the same color, so that small differences are evened out.

The image with the Mean Removal filter applied to it.
The image with the Mean Removal filter applied to it.

The image with the Mean Removal filter applied to it.

## The Oilpaint filter

An oilpaint effect is given to the image by creating patch-shaped areas in which the most important color is applied to the entire area.

The image with the Oilpaint filter applied to it.
The image with the Oilpaint filter applied to it.

The image with the Oilpaint filter applied to it.

## The Pixelize filter

The image is pixelated by taking a square area and giving it the mean color value of the pixels it contains.

The image with the Pixelize filter applied to it.
The image with the Pixelize filter applied to it.

The image with the Pixelize filter applied to it.

## The Raindrops filter

This filter makes it look like raindrops have fallen on the image by distorting drop-shaped areas with a lens-like effect as one would see when looking at the image through a real raindrop. Some raindrops will have a fish-eye lens effect.

The image with the Raindrops filter applied to it.
The image with the Raindrops filter applied to it.

The image with the Raindrops filter applied to it.

## The Round Corners filter

This filter just rounds off the corners of the image. This is done by making the outside of the rounded corner transparent.

The image with the Round Corners filter applied to it.
The image with the Round Corners filter applied to it.

The image with the Round Corners filter applied to it.

## The Sharpen filter

This filter sharpens the image.

The image with the Sharpen filter applied to it.
The image with the Sharpen filter applied to it.

The image with the Sharpen filter applied to it.

## The Simple Noise Reduction filter

This filter reduces noise in the image by giving loose pixels a color close to the surrounding area. This causes small details to be lost, but can enhance the general view of the image when this is hampered by too many unnecessary details.

The image with the Simple Noise Reduction filter applied to it.
The image with the Simple Noise Reduction filter applied to it.

The image with the Simple Noise Reduction filter applied to it.

## The Small Tiles filter

The picture is reduced in size and repeated multiple times.

The image with the Small Tiles filter applied to it.
The image with the Small Tiles filter applied to it.

The image with the Small Tiles filter applied to it.