# Special Effects (Filters)

## Simulate Infrared Film

The &digikam; Infrared Film filter simulates traditional infrared film material.

## Introduction

Simulating classical infrared film material (the effect is rendered in black and white) is an interesting alienation effect that is even stronger and more dramatic than pure black and white conversion. Contrast and an abstract touch are improved, which can underpin the expression of the photographer as an artist. It is like taking an image in black and white with a red filter on the camera lenses. Areas which reflect little red light, ⪚ the sky, will show as low density, dark areas. Areas which are excellent reflectors of red light, e.g. most green foliage, will be high density areas. And snow landscapes are really dramatic.

The algorithm is based on the method of the 'Simulate Infrared Film' tutorial of the GimpGuru.org web site available at this url. The filter tries to reproduce the famous Ilford(tm) SFX200 infrared film. This film has a sensitivity range of 200-800 ISO.

### Using the Infrared Filter

The left part of the dialog window lets you select the region to be shown in the preview section. Move the red rectangle with the mouse around to show the effect on different parts of the image.

The lower part provides the two controls, Film Grain and ISO sensitivity. Check the Add Film Grain box if you want to simulate the grainy texture of a high sensitivity film. The ISO-level slider modifies the amount of filmgrain added and the predominance of green color (chlorophyll in nature) in the conversion mixer. Green pastures will become white as snow! Try it out.

Because the filter mixes color channels to reproduce infrared film (with emphasis on green channel), one can not simulate infrared effect from black and white original photograph, since the color information is missing.

### The filter in action

This is an example of the infrared film effect applied to a color image taken in New Zealand's landscapes. The original image is (1) and the converted image is (2). The film sensitivity used to simulate the infrared film is ISO-400. Higher ISO values will create a kind of aura in the highlights.

The Infrared filter in Action

## Film Grain

The &digikam; Filmgrain filter reproduces traditional film grain techniques of high speed films.

## Introduction

The &digikam; Filmgrain filter is an easy tool to produce film grain on your images as known from classical high speed film material as, for example, the famous B/W KodaK Tri-X. In order to increase film sensitivity, manufacturers employed larger silver grains in the photo emulsion.

The film grain effect gives your shot a particular mood or seems to transport it in time. The treated image acquires a timeless atmosphere, detached from every day life. If you want that gritty, art-house, street-photography grainy film look, especially in monochromatic photos, use this filter.

### Using the Filmgrain filter

There is a slider calibrated in ISO-sensitivity to control the grain intensity and granularity. The default is set to ISO-2400, although higher values are often required. If you still want more grain, apply the filter several times.

### The filter in action

This is an example of the film grain effect applied on a black and white image. The original image is (1) and the corrected image is (2). The film sensitivity used for simulate the film graininess is ISO-1600.

The Film Grain Filter in Action

## Oil Paint

The &digikam; Oil Paint filter gives your image the look of an oilpainting. It uses an algorithm copyrighted by Pieter Voloshyn.

## Introduction

The &digikam; Oil Paint filter gives your digital images a nice oilpainting-like look. Images of nature and still lifes are well suited for this effect.

### Using the Oil Paint filter

There are two sliders to control the effect. The upper slider selects the Brush Size between 1 and 5. Bigger brushes are better suited for large images. Smooth controls the smoothness or, seen from the other end, the jaggedness.

### The Oil Paint filter in action

This is an example of the oil paint filter effect. The original image is (1) and the transformed image is (2). Brush Size for this 640 pixel size image is 1, Smooth is 17.

Oil Paint Image Effect Preview

## Charcoal Drawing

The &digikam; Charcoal is an effect filter that creates a charcoal sketch-like result.

## Introduction

The &digikam; Charcoal filter uses the gradients of color and luminosity to produce a grey scale charcoal sketch. The lines defining the outline of the image are pronounced. Images with slowly changing gradients are not ideal for this effect. It is helpful to imagine what scene you would pick to do as a hand sketch yourself, in order to choose the image to start with.

### Using the Charcoal filter

There are two sliders to control the effect on a scale of 1-100. The upper slider selects the pencil size, whereas the second slider adjusts the contrast (smoothness).

### The Charcoal filter in action

This is an example of the charcoal filter. The original image is (1) and the transformed image is (2). Default values of 30 and 10 where applied. The result can be improved by adjusting the luminosity levels.

The Charcoal filter in Action

## Emboss Image

The &digikam; Emboss filter sculptures your image into 3-D as if it were stamped into wax. It uses an algorithm copyrighted by Pieter Voloshyn.

## Introduction

The &digikam; Emboss filter is a quick tool to render your images in a 3-D effect. It works particularly well on images with simple structure where color is not the most important content. The filter uses the difference between colors and luminosity to convert it into a grey, moon-like landscape lit from 10 o'clock.

### Using the Emboss filter

The Depth control allows to define the contrast of the filtering. A value of 30 (10%) is the standard.

### The Emboss filter in action

This is an example of the emboss filter. The original image is (1) and the transformed image is (2). The Depth applied is 10%.

The Emboss filter in Action

## Distortion FX

The &digikam; Distortion FX is a series of distorting effects for digital still images.

## Introduction

With this filter set, you can transform an ordinary photograph into a work of art suitable for framing using distorting operations. It uses algorithms copyrighted by Pieter Voloshyn.

### Using the filter

These are the distorting effects available:

Type | Preview
Fish Eyes: warps the photograph around a 3D spherical shape to reproduce the common photograph 'Fish Eyes' effect. |
Twirl: spins the photograph to produce a Twirl pattern. |
Cylinder Horizontal: warps the photograph around a horizontal cylinder. |
Cylinder Vertical: warps the photograph around a vertical cylinder. |
Cylinder H/V: warps the photograph around a 2 cylinders, vertical and horizontal. |
Caricature: distorts photograph with 'Fish Eyes' effect inverted. |
Multiple Corners: splits the photograph like a multiple corners pattern. |
Waves Horizontal: distorts the photograph with horizontal waves. |
Waves Vertical: distorts the photograph with vertical waves. |
Block Waves 1: divides the image into cells and makes it look as if it is being viewed through glass blocks. |
Block Waves 2: like Block Waves 1 but with another version of glass blocks distortion. |
Circular Waves 1: distorts the photograph with circular waves. |
Circular Waves 2: other variation of Circular Waves effect. |
Polar Coordinates: converts the photograph from rectangular to polar coordinates. |
Unpolar Coordinates: Polar Coordinate effect inverted. |
Tiles: splits the photograph into square blocks and move them randomly inside the image. |

Some effects can take a long time to run and cause high CPU load. You can always abort an effect by pressing Abort button during preview rendering.

### The Distortion filter in action

The Distortion FX dialog tool in action is available below.

The Distortion FX Dialog Tool Preview

## Blur FX

The &digikam; Blur FX is a series of blurring effects for digital still images.

## Introduction

With this filter set, you can transform an ordinary photograph into a work of art suitable for framing using blurring operations. It uses algorithms copyrighted by Pieter Voloshyn.

### Using the Blurfx

These are the blurring effects available:

Type | Preview
Zoom Blur: blurs the image along radial lines starting from a specified center point. This simulates the blur of a zooming camera, thereby giving the photograph a dynamic expression as often seen in sport photography. |
Radial Blur: blurs the image by rotating the pixels around the specified center point. This simulates the blur of a rotating camera. |
Far Blur: blurs the image to simulate the effect of an unfocused camera lens. The subject seems to recede into the background. |
Motion Blur: blurs the image by swishing the pixels horizontally. This simulates the blur of a linearly moving camera, i.e. like a shot taken from a car or train. |
Focus Blur: blurs the image corners to reproduce the astigmatism distortion of a lens. |
Softener Blur: blurs the image softly in the darker tones and strongly in the high lights. This gives photographs a dreamy and glossy soft focus effect (Hamilton effect). It's ideal for creating romantic portraits, glamour photography, or adding a warm and subtle glow. |
Shake Blur: blurs the image by randomly moving the pixels simulating the blur of an arbitrarily moving camera. |
Smart Blur: finds the edges of color in photograph and blurs them without muddying the rest of the image. |
Frost Glass: blurs the image by simulating randomly dispersing light filtering through hoarse frosted glass. |
Mosaic: blurs the image by dividing the photograph into rectangular cells and then recreates it by filling those cells with average pixel value. |

Some effects can take a long time to run and cause high CPU load. You can always abort an effect by pressing the Abort button during preview rendering.

### The Blurfx in action

An example of the Blur FX dialog in action is shown below.

The Blur FX Dialog Tool Preview

## Rain Drops

The &digikam; Raindrops filter puts beautiful raindrops on your image.

## Introduction

The Raindrops is nice little tool to put raindrops onto your images. Naturally, it renders your image in a kind of wet look. It uses an algorithm copyrighted by Pieter Voloshyn.

### Using the Raindrops filter

Three sliders give you control over the effect filter:

Drop size obviously allows to change the size of the drops. As the drop size doesn't automatically scale with the image size it is often necessary to reduce the size for small images. Number changes the number and density of drops. Fish eye changes the optical effect of the drops across the image.

You can keep a zone clear of raindrops with the &digikam; Image Editor Select tool. Selecting the area to avoid (for example a face) before launching the Raindrops filter will keep it free from rain drops.

### The Raindrops filter in action

This is an example of the raindrops filter. The original image (1) shows a quiet sunset, the transformed image (2) indicates a sunset after a thunderstorm. Default values have been used for this example.

Rain Drops Image Effect Preview