Add-ons

Much of ArtPaint's functionality comes through add-ons. Add-ons are small programs that ArtPaint can load to do some specific job. The add-ons can be accessed through paint-window's Add-Ons-menu. Currently all add-ons affect only one layer at a time.



Descriptions of the included add-ons

This part briefly describes the add-ons that are included with the current version.
Adaptive Histogram Equalization
A Contrast Limited Adaptive Histogram Equalization algorithm that can improve contrast in a Greyscale image. A colour image will be converted to greyscale before the algorithm is applied.
Anti-Dither
Attempts to reverse the effects of dithering an image. It will considerably reduce the resolution.
Blur
Opens a window that allows you to adjust the blurriness of the image with a slider. The blur is reflected on the image when you let go of the slider.
Brightness
Opens a window that allows you to adjust the brightness of the image with a slider. The change in brightness is reflected on the image right when you move the slider.
Color Balance
Opens a window that has three sliders for controlling the amount of red, green and blue color in the image. The change in color-balance is reflected in the image at the moment you move the sliders.
Color Separator
Extracts the Cyan, Magenta, Yellow or Key/Black components of an image. Only useful to make colour separations for printing.
Contrast
Opens a window that has a slider for adjusting the contrast of the image. The change in contrast is reflected in the image right away.
Detect Edges
The resultant image will be black except for the exact edges, which will have highlighted colour. Note: it does not change transparency.
Dispersion
Changes the pixels positions in the image randomly a little bit to create a "dispersed" look.
Emboss
Creates an emboss effect on the image.
Enhance Edges
Increases colour "distance" at edges
Gaussian Blur
Blurs the image using a Gaussian function; see the Wikipedia article
Greyscale
Converts the image into greyscale.
Halftone
Creates a halftone-pattern on the image. The foreground-color is used to color the dots and the background-color fills the background.
Interference
Generates a "Wave Interference Pattern" from two "point sources" in a layer. The location of the sources can be adjusted with the mouse. Any original image in the layer and colour settings are completely ignored.
Marble
Overlays a random "Marble" effect on the image, using the foreground colour.
Negative
Creates a negative image of the picture by inverting every color. The inversion is done in RGB-color-space
Oil
Creates a pattern on the image that tries to simulate the effect of painting the image with brush strokes.
Polar Mapper
Generates a rectangular-coordinate image from the polar coordinates of the original. Useful in some image analysis schemes. If R is the distance from the centre of the original image, and θ is the angle from the x-axis, the resultant x = log R and y = θ.
Reducer
Reduces the number of colours used in an image to a specified maximum. The result may be dithered with a variety of algorithms. The palette used may be the 256-colour BeOS (and Haiku) map, or a generated optimal one using the Generalized Lloyd's Algorithm. (The latter may be very slow, so an indication is posted in the control window while it is active.)
Saturation
Opens a window that contains a slider for controlling the saturation of the image. The effect is reflected on the image right when the slider is moved.
Sharpness
Changes the (apparent) sharpness of the image.
Stretch Histogram
Improves the contrast of the image by stretcing its histogram to maximum possible length. If the image contains pure black and pure white this operation will do nothing.
Threshold
Generates a new image with all the pixels of the original that were lighter than the specified threshold in the foreground colour, and those less than the threshold in the background colour. The threshold is set by clicking or dragging the mouse in the histogram area of the panel. (Takes effect on mouse-button release.) You can select on overall intensity, or specifically on Red, Green, or Blue.
Twirl
Makes a twirl-effect on the image. Opens a window with two sliders for controlling the size and the direction of the twirl. The center for the twirl can be set by clicking on the image and dragging around.
Wave
Creates a circular wave effect on the image. Opens a window that controls sliders for controlling the length and the strength of the wave. The wave center can be adjusted by clicking on the image with the mouse and dragging around.
PerlinWood
Creates a wood-like texture over the image.

Adding add-ons

The suite of add-ons is not fixed, and new ones might be created in the future. You can in fact make your own; it was once intended that there should be a Developer's kit, but it never actually arrived. For now, the best bet would be to go to the master source archives at HaikuArchives, and look at how the current set have been coded.

If you installed ArtPaint as a Haiku Package, its folders will be read-only, so a new add-on currently can't just be plugged in directly — unless it is also supplied as a package, in which case just drag that to /boot/system/packages. Otherwise you would have to copy the ArtPaint folder to be run from some writeable area and put the add-on in the "add-ons" subfolder there.