Quick example

Learning by example is powerful, so let's start by applying a grayscale filter to each thumbnail and add a copyright notice to the corner of each closeup image. (For a formal description of available filter features, see below.)

Start the jAlbum application and prepare a project for album creation. Now go to the Advanced page of jAlbum. There you will find a section called "User defined variables". We will use this section to set the properties of our filters. Enter exactly as this example shows. Pay attention to capitalization, ("GrayscaleFilter" is different to Grayscalefilter").

Setting filter properties on the Advanced page

Now go to the Main page and press "Rebuild all" to have the album generated and filters applied. (Pressing "Rebuild all" is important as pressing "Make album" does not process images if they already exist from a previous album generation.) The resulting thumbnails and closeup images should now look something like this:

Thumbnail and closeup images processed through grayscale and text filters

The filters are applied in the order they are numbered (filter1, filter2 etc). The filter settings gets saved with the album project so don't forget to save your project when you are happy with your settings.

The filters

Below is a list of the initially provided filters and their properties (features). New filters can be installed by putting their Java class files inside the plugins directory of jAlbum. All filters require the class property to be specified as filter identifier. All filters accept the thumbnails and closeups property that controls if the filter is to be applied to thumbnails only, closeups only or both. Default is both.

Missing a filter? Please also look for filters made by jAlbum users in the forum.

Grayscale filter

Converts images to grayscale.

class=GrayscaleFilter

Tint filter

Adjusts the color of an image.

class=TintFilter redPercent=100 greenPercent=60 bluePercent=60

You can get interresting effects by combining the tint filter with the grayscale filter.

Logotype filter

Adds image/logotype of your choice on top of album images.

class=LogoFilter src="http://blog.jalbum.net/dor.png" strengthPercent="50" closeups

class=LogoFilter src="file:///C:/adir/anotherdir/animage.jpg" closeups

Text filter

Adds texts to album images.

class=TextFilter text="Date: $fileDate" size=20 color=#aaffaa closeups

Shadow text filter

Like text filter but also adds a drop shadow.

Extended properties (see TextFilter for the others):

class=ShadowTextFilter text="Date: $fileDate" size=20 color=#aaffaa closeups

Watermark filter

Like text filter but with a watermark effect.

Extended properties (see TextFilter for the others):

class=WatermarkFilter text="jAlbum" size=30  closeups valign=bottom margin=0

Zoom filter

Zooms into images. Good for making thumbnails more interpretable.

class=ZoomFilter prescale thumbnails zoomPercent=30

Fixed shape filter

Crops images if needed so they exactly fit the dimensions set for "thumbnail size" or "max image size" in the user interface. This makes all images and/or thumbnails the same shape (portrait, squary etc).

class=FixedShapeFilter prescale thumbnails

Sharpen filter

Sharpen images.

Blur filter

Blur images.

class=BlurFilter closeups

Rotation filter

Rotates images a specified degree or a random degree (per image)

class=RotationFilter angle=10 random thumbnails prescale

eXtended Border filter

Adds borders. frames and shadows of your choice on album images.

class=XBorderFilter frWidth=20 frCol=ivory shWidth=15 closeups

class=XBorderFilter boWidth=20 boCol=ivory closeups

Adding filters to skins

Skins can be configured to automatically use certain filter settings.

Simply save a project containing suitable filter settings in the "User defined variables" section, then rename the project file to hints.jap and put it in the skin folder. jAlbum will now load filter settings from this file when such a skin is selected. Remember to also strip the hints file from other settings that you don't want to be applied.

Developing filters

This section is for Java programmers who wish to extend jAlbum with new image filters.

jAlbum image filters are java classes added to the plugins directory that implement the small se.datadosen.jalbum.JAFilter interface. A jAlbum filter should also adhere to the JavaBean specification, meaning:

• Provide a no-args constructor
• Getters and setter methods should follow the JavaBean naming convention.
• The filter should be serializable

A se.datadosen.jalbum.JAFilter interface must provide getter methods for name and description pretty much like an Applet. The third method is the filter method that takes a BufferedImage and a java.util.Map as arguments and returns a modified BufferedImage. A filter is allowed to directly manipulate the passed BufferedImage. The Map object contains jAlbum $variables that may be useful for the filter implementer.

The preferred way to pass parameters to a filter is to implement setter methods for them. By using a smart BeanShell script in the init.hsh file in the jAlbum program directory, jAlbum is capable of passing attributes from the user defined variables section of the Advanced tab page to the corresponding setter method of a filter.

The plugins jAlbum directory contains not only the filter classes but also the source code for the filters described on this page. Feel free to use them as base for your own filters. You will probably find the SimpleFilter below a good base for your own filters. The plugins folder also contains a compile.bat file that simplifies compilation for you. As you develop filters, please note that you do not need to restart jAlbum in order to refresh the filter classes as they are dynamically loaded every time an album is being processed. Finally, if you make a cool filter, please send it to me for inclusion.

Sample filter source code

The following simple filter adds a jAlbum logo to the corner of images:

import se.datadosen.jalbum.JAFilter;
import java.awt.*;
import java.awt.image.BufferedImage;
import javax.swing.ImageIcon;

/**
 * jAlbum simple image filter adding a jAlbum logo to the
 * corner of images
 * @author David Ekholm
 * @version 1.0
 */
public class SimpleFilter implements JAFilter {

    // Implements JAFilter
    public String getName() {
        return "Simple filter";
    }

    // Implements JAFilter
    public String getDescription() {
        return "Add a jAlbum logo to the corner of images";
    }

    // Implements JAFilter
    public BufferedImage filter(BufferedImage bi, java.util.Map vars) {
        Graphics2D g = bi.createGraphics();
        ImageIcon windowIcon =
         new ImageIcon(se.datadosen.jalbum.JAlbumFrame.class.getResource(
          "smallicon.gif"));
        g.drawImage(windowIcon.getImage(), 0, 0, null);
        return bi;
    }
}