Generating static tiles

As mentioned in the previous chapter, the IIIF Image API defines the following structure:

http://host:port/identifier/region/size/rotation/quality.format

It is possible to generate images that fit this URL structure and conform to the IIIF Image API using a tile generator. This will generate the minimum required amount of files to implement the IIIF Image API. It does have some limitations, the main one being it is not possible to request images of a size that haven't been pre-generated. This type of pre-generated IIIF Image is known as a Level 0 implementation.

To generate these IIIF images we are going to use a IIIF tilling program which is available on Github. This workshop is useful for those that are looking for a cheap method of making a small amount of images available although there are instances where this method can be scaled to support hundreds of thousands of images. See this article for a method of making level 0 images scalable: The Code4Lib Journal – Scaling IIIF Image Tiling in the Cloud.

Prerequisites

Java

In this workshop we will install and run a IIIF Image server and for this you will need Java 11 installed.

• Downloading Java 11

To verify you have the correct package installed, you can run the following command from a terminal or command prompt:

$ java -version
# java version "1.11.0_102"

You should see version 1.11.x. For more information on the install options see:

• Java install options

Step 1: Download the IIIF Tiler

• Navigate to the release page: https://github.com/glenrobson/iiif-tiler/releases/tag/0.9.1
• Click the assets drop down
• Download iiif-tiler.jar
• Store this jar file in your ~/iiif-workshop directory

Step 2: Prepare your image files

• Move the image files you want to work with into your ~/iiif-workshop directory

Step 3: Generate the IIIF Image tiles

Now either:

• Double click on the iiif-tiler.jar file in Finder or Windows.

or

• from the command line run:

cd ~/iiif-workshop
java -jar iiif-tiler.jar

• This will generate the IIIF image tiles in a iiif directory for every image it finds in the same directory as the iiif-tiler.jar.

Common issues:

If you see the following error:

Exception in thread "main" java.lang.IllegalArgumentException: Failed to find combination under 100 files

Try running the following command:

java -jar iiif-tiler.jar image_filename 5

Where image_filename is the filename of your image e.g. image.jpg

Step 4: Point the Chrome webserver to your iiif-workshop directory

We will cover the Chrome WebServer in more detail in the Presentation API session but this plugin makes your laptop work like an image server.

• Open Chrome
• Click the Apps button on the top left

• Click on the Web Server (if this is not listed ensure you have installed the prerequisites).
• You should see the following:

• Click choose folder and select your iiif-workshop folder
• Where it says Enter port change it to 8887
• Click Show Advanced Settings
• Ensure Set CORS headers has a tick next to it.

Step 5: Serve your IIIF Image through a http server

• Open a browser and navigate to http://127.0.0.1:8887/
• You should see a iiif directory and if you click that you should see your image file.
• Click this directory then click on the info.json.
• If your image was called image.jpg the URL should be.

http://127.0.0.1:8887/iiif/image/info.json

• If you see the info.json you are now ready to view your image in a IIIF Image viewer.

Step 6: Show your image in a IIIF Viewer

You can now load your image to a IIIF image viewer. The main image viewer is OpenseaDragon. This takes the URL of the info.json. So if your info.json URL is:

http://127.0.0.1:8887/iiif/image/info.json

Open it with OpenseaDragon:

http://iiif.gdmrdigital.com/openseadragon/index.html?image=http://127.0.0.1:8887/iiif/image/info.json

Step 7: Hosting your image publicly

You now have a working level 0 implementation. As you are using the Chrome plugin the images are only accessible on your machine. You can't share your images with other people. To be able to share your images you need to copy them to a public Web Server. As mentioned there are paid for services but you can also access free Web Hosting through GitHub which we will do next.