More about image filters

Image filters can be plugged in to enhance images during album generation, adding watermarking, logos etc. Image filters can be applied to closeup images, thumbnail images or both. The permitted combinations are listed here Several filters can be chained to produce the desired effect. Imagine first applying red-eye reduction, then sharpening images and finally adding your logo to a corner. An open API and source code example are provided so developers easily can add new filters.

From the effects panel you can easily add watermarks (text and/or logo), greyscale, contrasts and a few arty filters. All available filters are not added in the user interface, they can be controlled with some fairly simple settings in the "User defined variables" section of the "Advanced page.". These filters can be applied both globally and on a folder by folder or even individual image basis.

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 "Force Remake" to have the album generated and filters applied. (Pressing "Force Remake" 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 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.

Note, the '|' character represents 'or', so true|false means the value can be true or false

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

Grayscale filter

Converts images to grayscale.

Example

class=GrayscaleFilter

Applies the grayscale filter to both thumbnails and closeups.

Tint filter

Adjusts the color of an image.

Example

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

Applies a redish tint to images.

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

Logotype filter

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

Examples

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

Add a semi transparent jAlbum logo from the jAlbum web site to center of closeups.

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

Pick an image from the local hard disk instead from a remote location.

Excluding an image
You can exclude an individual image from the album-wide logotype filter by opening the image for editing in jAlbum, opening the Variables panel on the right, and entering a new variable with the name applyLogo and a value of false.

Text filter

Adds texts to album images.

Example

class=TextFilter text="Date: $fileDate" referenceWidth=800 size=20 color=#aaffaa closeups

Add the file date of the image on top of the image in a light green color, adjust the font size if the image size differs from the reference width. To ensure the date used is the date the photo was taken use originalDate (fileDate may get modified)

Shadow text filter

Like text filter but also adds a drop shadow.

Extended properties (see TextFilter for the others):

Example

class=ShadowTextFilter text="Date: $fileDate" size=20 color=#aaffaa closeups
To ensure the date used is the date the photo was taken use originalDate (fileDate may get modified)

Add the file date of the image on top of the image in a light green color with a black shadow.

Watermark filter

Like text filter but with a watermark effect.

Example

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

Add a "jAlbum" watermark to the lower left edge

Zoom filter

Zooms into images. Good for making thumbnails more interpretable.

Example

class=ZoomFilter prescale thumbnails zoomPercent=30

Applies the zoom filter to thumbnails. Note the very important prescale attribute

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 thumbnails, or just thumbnails, the same shape (portrait, squary etc).

Example

class=FixedShapeFilter prescale thumbnails

Applies the fixed shape filter to thumbnails. Note the very important prescale attribute.

FixedShape filter should either be used for both thumbnails and closeups before scaling takes place or on thumbnails only, before scaling takes place.

It does not support for the combination of "closeups" and "prescale", if both are used the "prescale" will be ignored.

Constrain ratio filter

Limits the aspect ratio of a processed image. This prevents panoramic images, for example, from producing long skinny thumbnails.

Example

class=ConstrainRatioFilter prescale thumbnails maxRatio=2.5

Applies the constrain ratio filter to thumbnails, and limits the output aspect ratio (width/height) to a maximum of 2.5.

Note that many skins include this filter by default, or as a skin checkbox option. Check the skin you are using before applying it manually.

Sharpen filter

Sharpen images.

Example

class=SharpenFilter closeups

Applies the sharpen filter to closeups.

Blur filter

Blur images.

Example

class=BlurFilter closeups

Applies the blur filter to closeups.

NameTagFilter

Name tag filter.

Adds a small label using the name entered in Set area tags... or from XMP regions data. The label appears on images in the same location as shown in the 'Set area tags...' preview.

Example

class=NameTagFilter closeups

Applies the filter to close up images.

Margin filter

Add margin.

Adds a n pixel margin around each image. By default, the margin is transparent (if generating PNG images), but any color with any transparency level works. Since v18.3

Example

class=MarginFilter margin=10 color=#33AAAAAA

Apply a 10 pixel semi transparent light gray margin around images

eXtended Border filter

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

Examples

Adds a frame and a drop shadow to your closeups.

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

Adds a border to your closeups.

class=XBorderFilter boWidth=20 boCol=ivory closeups

Excluding images from filters

You can exclude an individual image from globally applied filters.

In Edit view, add an image specific user variable called "excludeFilters". Set the value to the name of the filter class (or names of the filter classes, comma separated).

Adding filters to skins

Here is an example of adding image filters to a skin, in this case a watermark filter applied to the slide images; watermark and watermarkSize would be skin variables from onload.bsh. The code is added to init.bsh.

if (watermark.length() > 0) {
	WatermarkFilter f = new WatermarkFilter();
	f.setText(watermark);
	f.setSize(watermarkSize);
	f.setAlign("center");
	f.setValign("bottom");
	engine.addFilter(f, JAFilter.CLOSEUPS_POSTSCALE_STAGE);
}

And to add the constrain ratio filter for thumbnails:

engine.addFilter(new ConstrainRatioFilter(0.5f, 2f), JAFilter.THUMBNAILS_PRESCALE_STAGE);

Extending jAlbum's image 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;
    }
}

More Examples

Adding a 30px tall red box to the bottom of slide images with a web address in white text.

Making images have the same area, or number of pixels, see LimitAreaFilter forum post