Biomed Imaging Interv J 2006; 2(2):e32
doi: 10.2349/biij.2.2.e32
© 2006 Biomedical Imaging and
Intervention Journal
TECHNOLOGY IN IMAGING TUTORIAL
Creating animated medical images (Part 1)
NA Kadri*, MBiomedEng,
MG Raha, MBiomedEng
Department of Biomedical Engineering, Faculty of Engineering,
University of Malaya, Kuala Lumpur, Malaysia
Introduction
With the advent of the Internet and World Wide Web (WWW), different image format became available. Some were static (GIF, JPEG) while others are animated (animated GIF, MPEG, Shockwave). Each carries distinct advantages for a given need and purpose, particularly for efficient transmission over the network. For instance, a GIF file is highly suitable for encoding diagram-like images – images that consist of line art and flat colour, whereas a JPEG is the chosen format for encoding images with photographic quality [1].
In encoding animated images, an animated GIF would be the
chosen format for encoding a simple animation generated by a sequence of vector
graphics while an MPEG format is preferred if animation with a movie-like
quality is desired. Both these formats employ different algorithms to achieve
the best animation quality at the optimal file size for network transmission
[2].
Although the initial objective of developing the network,
which later formed the framework for today’s Internet, was military in nature,
the interconnectivity of these vast computing resources promises to be of much
use for general users as well [3]. One of the driving factors behind the
development of various applications and protocols, including the WWW, is the
possibility of unlimited sharing of resources. The progress of the WWW has
spawned a myriad applications in numerous areas, be it for educational,
research, or recreational purposes [4]. For instance, in the area of medical
education the use of animation as a teaching tool has been proven to be one of
the most effective methods in delivering learning materials [5,6]. Just by
having a web browser, which incidentally can be acquired free of charge, the
advantages of learning via animation may be shared with a large number of
users.
This tutorial will try to document a few simple steps
involved in producing animated images from a series of medical images, using
widely available software. The image samples (in both GIF and JPEG formats)
from a computed tomography (CT) study are also available for download.
Software
This two-part tutorial covers the use of applications that create animated GIFs, with the exception of MS PowerPoint, which produces animation that may only be used in a .ppt or .pps file. Animated GIF is chosen because of its cross-browser viewing capability and small file size (depending on the original source images).
Part 1 of this tutorial will focus on the use of proprietary
software, while Part 2 will discuss the use of shareware and freeware
applications that can be downloaded from the Internet. The list of software
used in Part 1 is as follows:
●
Proprietary – MS PowerPoint (Microsoft Corp., Redmond, WA, USA)
●
Proprietary – Adobe ImageReady (Adobe Systems Inc., San Jose, CA, USA)
The discussion is by no means exhaustive and readers are
encouraged to look up the respective vendor websites, or the various online
tutorial websites dedicated to these software.
To fully utilize the examples in this tutorial, a series of sequential images
are needed. One may source these images themselves or download
directly from this hyperlink: http://www.biij.org/2006/2/e32/images.zip
(923 KB). The ZIP file contains two folders containing 15 sequential
JPEG and GIF images respectively, taken from a CT study at the
University of Malaya Medical Centre, Malaysia (courtesy Prof.
KH Ng).
The ZIP file has to be ‘unzipped’ before the images may be
used. A popular utility is WinZip (WinZip International LLC, Mansfield, CT, USA),
and an evaluation version may be downloaded at no charge from the website
(http://www.winzip.com) or Download.com (http://www.download.com). The image
files will be located inside two folders named “sample jpg” and “sample gif”,
and this tutorial will assume that the ZIP file is unzipped at the c:\
directory. All the examples used in this tutorial have been tested using
Windows® XP Professional Edition® (Microsoft Corp., Redmond, WA, USA) and may
still work on other versions of Windows® operating systems.
MS PowerPoint
MS PowerPoint is the most commonly used presentation
software on the PC platform. Depending on the release version, it has a number
of effects that can be used to create animation.
Step 1 – Open MS PowerPoint, and click on Insert >
Pictures > From File…
Step 2 – Select the c:\sample jpg\ folder, and select
all images within the folder by clicking Ctrl+A (Figure 1). Click Insert
when finished.
Step 3 – The selected images are inserted into the slide;
arranged diagonally from left to right (Fig. 2). The images now need to be
aligned at the centre of the slide. To do this, select all images (Edit >
Select All (or Ctrl+A)) and click Draw > Align or Distribute
> Align Center, followed by Draw > Align or Distribute > Align
Middle from the Drawing toolbar. Ensure that Draw > Align or
Distribute > Relative to Slide is checked. The images should appear as
one and aligned at the centre of the slide (Fig. 2).
Step 4 – To create the animation, click Slide Show >
Custom Animation…, and the Custom Animation task pane will appear on the
right side of the screen. The types of animation available depend on the MS
PowerPoint version used, and this tutorial uses the “Fade” effect. To do this,
select all images (Edit > Select All (or Ctrl+A), and click Add
Effect > Entrance > Fade (Fig. 3). If “Fade” is not on the list,
click on More Effects…
Step 5 – To produce a smooth transition between the images, customise
the animation by modifying the “Fade” effect. At the Custom Animation task
pane, select After Previous for the Start option; and select Very
Fast for the Speed option.
Step 6 – The animation is now ready, and may be viewed by clicking Slide
Show > View Show (or Ctrl+F5). An example of the
MS PowerPoint file produced may be viewed at http://www.biij.org/2006/2/e32/sample.pps
(546 KB).
Since MS PowerPoint is capable of handling multiple image
formats, including GIF, JPEG, TIFF, PNG, any sequential images of these formats
may be animated using the above steps. The final file size depends on the
number of images used, and the original file size of the inserted images.
The above tutorial is written based on MS PowerPoint 2003
version, but may still be used with other versions of MS PowerPoint with very
slight alterations.
Adobe ImageReady
This proprietary software is from Adobe Systems, and availableas
a package with Adobe Photoshop. It is primarily used to produce optimized
images for web pages, including selective compression for JPEG, GIF, animated
GIF, rollover images, and image maps. This tutorial will only focus on
producing an animated GIF using the sample images provided.
Step 1 – Open Adobe ImageReady, and click on File >
Import > Folder as frames…
Step 2 – Select the c:\sample jpg\ folder, and a new
document is displayed (Fig. 4). This document actually contains the sequential
images arranged in layers. A smaller pane located below the document displays
the sequence of the images.
Step 3 – To produce an animated GIF, click File > Save
Optimized As…, and select the destination. Click Save when finished.
Figure 5 shows the resulting animated GIF.
One may preview the output in any web browser before
producing the animated GIF by clicking File > Preview In > Internet
Explorer (or Ctrl+Alt+P). Users may add additional web browsers by
clicking File > Preview In > Other…
The dimension of the resulting animated GIF depends on the
original image dimensions. To reduce the final file size, users may reduce the
dimension of the document by resizing the document. Click Image > Image
Size… and enter the new dimensions in pixel values.
The above tutorial is written based on Adobe ImageReady 7.0
version, but may still be used with other versions of Adobe ImageReady with
very slight alterations.
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Received 1 May 2006; received in revised form 20 June 2006; accepted 23 June 2006
Correspondence:
Biomedical Engineering Dept, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia. Tel.: (603) 7967-6882, Fax: (603) 7967-4579;
E-mail: nahrizuladib@um.edu.my (Nahrizul Adib Kadri).
Please cite as: Kadri NA, Raha MG, Creating animated medical images (Part 1), Biomed Imaging Interv J 2006;2(2):e32
<URL: http://www.biij.org/2006/2/e32/>
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