DOI:10.2214/AJR.06.0514
AJR 2007; 188:W379-W383
© American Roentgen Ray Society
Medical Illustration Techniques for PowerPoint: Part 1, The Basics
Omar Lababede1 and
Moulay Meziane
1 Both authors: Department of Diagnostic Radiology, Section of Thoracic Imaging,
Cleveland Clinic Foundation, 9500 Euclid Ave., HB6, Cleveland, OH 44195.
Received April 17, 2006;
accepted after revision August 31, 2006.
Address correspondence to O. Lababede
(lababeo{at}ccf.org).
WEB This is a Web exclusive article.
Abstract
OBJECTIVE. The newer versions of PowerPoint (Microsoft) have drawing
tools that can be used to draw medical illustrations for presentations and
publications. Our purpose is to review the concept and elements of vector
computer graphics, explain the toolbar setup, introduce the basic techniques
of drawing with PowerPoint tools, and describe manipulation of a drawing by
changing the types of anchor points and lines. The advantages of illustration
with PowerPoint tools are viewed from three perspectives: drawing on a
do-it-yourself basis, using computers, and using PowerPoint tools.
CONCLUSIONS. The drawing tools of the newer versions of PowerPoint
can be useful in enhancing the visual component of presentations. Advanced
presentations can be developed with simple steps and tools. By learning the
drawing techniques of PowerPoint, radiologists can improve their ability to
communicate and deliver their messages eloquently.
Keywords: digital images • PowerPoint
Introduction
Medical illustrations have always been an indispensable tool of
medical education. Illustrations facilitate the conceptualization and
dissemination of information through visual communication; that is, "a
picture is worth a thousand words." Computers and illustration software
are widely used for generating professional medical illustrations. PowerPoint
(Microsoft) is the most widely used software for preparing electronic
presentations [1]. The newer
versions of the program have useful drawing tools that can enhance the
educational value of radiologic presentations. Radiologists are increasingly
using PowerPoint to prepare electronic presentations, and many of them are
using other software to edit digital radiologic images
[2]. Few radiologists, however,
have ventured into the field of digital medical illustration. The main
stumbling blocks for most of them are limited personal artistic skills and the
complexity of professional illustration software.
Over the last 2 years, we have been using PowerPoint tools to draw
high-quality illustrations for presentations. In doing so, we have found that
PowerPoint produces highquality drawings but is not as complex as professional
illustration software. Using a program such as PowerPoint is an advantage for
radiologists with limited time. In addition, drawing with PowerPoint does not
require professional artistic sk ill and has many other advantages. In this
first of two articles, we review the types of computer graphics and the basic
techniques of PowerPoint drawing and discuss the advantages of using
PowerPoint for drawing. Part 2
[3] consists of step-bystep
instructions through an example.
Computer-Generated Graphics
The approach to drawing with PowerPoint and other illustration software is
different from the process of traditional artistic drawing because drawing
with these software is vector-based. One must first be familiar with the types
of computer graphics to effectively use a computer for drawing. This
understanding is also essential to application of PowerPoint drawing
techniques. Computer-generated graphics are categorized into two types: bitmap
and vector [4].
Bitmap Graphics
A bitmap image (also called paint-type or raster image) consists of large
numbers of pixels arranged in a grid. Each pixel is assigned a certain color.
Digital photos, scanned graphics, and radiologic images are examples of bitmap
images. Bitmap-based drawings can be produced with the painting tools of image
editing or paint programs such as Photoshop (Adobe). The process of drawing a
bitmap illustration resembles that of traditional art but includes the help of
digital tools, such as brushes.
Vector Graphics
In vector graphics, mathematic relations between points and the paths
connecting them are used to describe an image
[5]. A vector image comprises
multiple vector objects. Each object has one or more paths composed of
straight or curved line segments or a combination of straight and curved
segments. Every line segment is defined by anchor points (vertexes) at each
end. This type of graphic is produced with special illustration programs such
as Illustrator (Adobe). The drawing tools in newer versions of PowerPoint also
generate vector-based illustrations.
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Fig. 1A —Differences between bitmap and vector graphics. 1 = right
brachiocephalic vein, 2 = left brachiocephalic vein. Bitmap drawing shows
anatomic relations between major structures in upper mediastinum, excluding
central airways. SVC = superior vena cava.
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Fig. 1B —Differences between bitmap and vector graphics. 1 = right
brachiocephalic vein, 2 = left brachiocephalic vein. Vector drawing of object
in A. Shading is more exquisite and realistic in A than in
B. Unlike A, B contains multiple and separate mathematically
defined objects. For example, each vascular structure in B is
considered one object and can be adjusted separately from other objects. SVC =
superior vena cava.
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Fig. 1C —Differences between bitmap and vector graphics. 1 = right
brachiocephalic vein, 2 = left brachiocephalic vein. Magnification of upper
left corners of bitmap (A, C) and vector (B, D) drawings.
Resizing of bitmap image decreases definition and increases pixelation.
Because it is not limited by pixel resolution of original drawing, vector
image maintains its clarity and detail when scaled to any size or printed at
any resolution.
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Fig. 1D —Differences between bitmap and vector graphics. 1 = right
brachiocephalic vein, 2 = left brachiocephalic vein. Magnification of upper
left corners of bitmap (A, C) and vector (B, D) drawings.
Resizing of bitmap image decreases definition and increases pixelation.
Because it is not limited by pixel resolution of original drawing, vector
image maintains its clarity and detail when scaled to any size or printed at
any resolution.
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Fig. 2 —PowerPoint (Microsoft) screen shot shows initial settings. A =
Drawing toolbar, B = Toolbar Options, C = Drawing option of Add or Remove
Buttons box, D = Line button, E = Select Multiple Objects button.
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A vector-based illustration can be easily edited by moving the anchor
points, adjusting curve attributes, or rearranging and changing the colors of
various objects. Vector drawings maintain their vectorlike qualities only in
illustration software. Therefore, before being inserted or used in another
application, such as a PowerPoint slide presentation, the drawing must be
saved in a bitmap-based format.
There are two main differences between bitmap and vector drawings: First,
unlike bitmap images, vector illustrations are not constrained by pixel
resolution; they are always displayed at the highest possible resolution.
Second, vector illustrations in general cannot be made as detailed as bitmap
images. Figure 1A,
1B,
1C,
1D shows the main differences
between bitmap and vector graphics.
Customizing PowerPoint Drawing Toolbars
PowerPoint drawing tools and commands are accessed with the Drawing toolbar
and menus. In the default setting, the Drawing toolbar is displayed in the
lower portion of the PowerPoint screen layout. If this toolbar is not visible,
click on View in the menu bar, then point over Toolbars and select Drawing.
Before proceeding with the discussion about drawing techniques, rearrange the
toolbars. This step is important because some essential buttons and toolbars
are not readily available with the default setting. The setting described is
the one that we use to permanently display the icons of these tools and
commands in the 2003 version of PowerPoint. After practicing with drawing
techniques, users can rearrange the toolbars based on their preferences and
practical needs.
First, on the Drawing toolbar, click the left mouse button on Toolbar
Options, located at the right margin of the toolbar and marked by a small
arrowhead pointing downward. A box appears indicating the option Add or Remove
Buttons. Placing the mouse pointer over this box produces another list of
options. Move the mouse pointer and place it over Drawing on the list. A new
list containing all the buttons of the Drawing toolbar emerges. The currently
selected buttons are checked. Deselect the Line button by clicking over it,
because this tool is available on another toolbar. Select the Select Multiple
Objects button, which is not available on the default toolbar, by clicking
over it (Fig. 2). Drag the
Drawing toolbar from its left edge to the left side to make space for
additional toolbars.
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Fig. 3 —PowerPoint (Microsoft) screen shot shows Autoshapes menu (A) and
Lines toolbar (B). Screen shots show steps of permanently displaying Lines
toolbar are dragging Lines toolbar from its top dotted holder and releasing it
to nearby area (C) and then dragging it down next to Drawing toolbar (D).
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Fig. 5 —PowerPoint (Microsoft) screen shot shows line drawing of left lung
and central airways. A = airways drawn with Freeform tool, B = lung drawn with
Curve tool. Right clicking inside lung and selecting Edit Points results in
display of anchor points (vertexes) as small squares (1) along curve. Curved
line segments (2) are present between vertexes. Menu appears after right
clicking over point. Check mark indicates type of point. Point type can be
changed by selection of different type from menu.
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Second, click on Autoshapes to display the corresponding menu. Place the
mouse pointer over the command Lines to show its details. Drag the new box
displayed from its upper edge and release it in the nearby space; then drag it
again and drop it next to the Drawing toolbar
(Fig. 3).
Third, in a similar manner, place the Order and Rotate or Flip toolbars
next to the previous ones. These commands are available on the Draw menu of
Drawing toolbar. The final outcome of the toolbar display is shown in
Figure 4, which also lists some
of the tools described in this article and in part 2
[3].
Basic Techniques of Vector Drawing in PowerPoint
Vector drawings of any illustration software have similar architecture. A
vector drawing consists of multiple objects. Each vector object contains one
or more paths. The line segments in a path are defined by anchor points
(vertexes). The direction and magnitude of a curved segment are adjusted by
changing the direction or length, or both, of the handles (direction lines)
that extend from each anchor point. The direction line is adjusted by dragging
the direction point at its end. Individual tools and techniques vary with the
software used. The following discussion of basic vector drawing techniques
applies specifically to PowerPoint.
In PowerPoint, the Lines toolbar has six buttons: Line, Arrow, Double
Arrow, Curve, Freeform, and Scribble (Fig.
4). We have found Curve and Freeform the most practical drawing
tools. The Curve tool is used primarily to draw an object with smooth, curved
line segments. The Freeform tool, on the other hand, can be used to draw
objects with straight or curved segments or both.
To draw using the Curve tool, select this tool from the Lines toolbar. If
the toolbars have not been set as described earlier, click AutoShapes on the
Drawing toolbar, point to Lines, and select Curve. Click where the curve
should start and then move the mouse, clicking wherever a curve is needed. To
end the curve as an open path, double-click. To form a closed path, make the
final click over the start point. When the Curve tool is used to draw an
object in PowerPoint, all the anchor points are designated Auto points. These
points can be displayed by right clicking inside the object and then selecting
the Edit Points option. To change the nature of one or more of these points,
position the mouse pointer over that point. When the mouse pointer is placed
over it, the point changes into a small square with four arrowheads along its
sides. Right click over the point and select one of the other options. The
options include Smooth Point, Straight Point, and Corner Point
(Fig. 5).
A Smooth point has two handles that are aligned and of equal length. Moving
one of these direction lines produces similar changes in the other line, and
the curved segments on both sides of the point adjust simultaneously. In
PowerPoint, a Straight point is similar to a Smooth point except that the
length of the handles can be changed independently of each other, producing
less-symmetric curves. A Corner point, which is helpful in producing sharp
curves at the anchor point, has handles that can be individually changed in
direction and length. Only the curve on the same side as the point changes
when the direction line is adjusted (Fig.
6A,
6B,
6C,
6D,
6E,
6F,
6G).
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Fig. 6A —Types of anchor points. Arrows in B-G indicate direction of
adjustment of directional point. Auto points of curved line segments. One
anchor point in object is labeled 1. Direction point (2) and Direction line,
or handle (3), appear after Auto point is changed into Corner point as
described in Figure 5.
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Fig. 6G —Types of anchor points. Arrows in B-G indicate direction of
adjustment of directional point. After Auto point is changed into Straight
point, handles remain aligned, but length of handles can be changed
independently, producing less-symmetric and somewhat angulated curve.
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In contrast to the Curve tool, the Freeform tool draws an object with both
curved and straight segments. Click where the curve should start, and then
drag to produce a freehand outline. To obtain straight lines, click, move the
mouse, and click again. Depending on the desired outcome, use either of these
techniques or a combination of them (dragging, clicking and moving, or both).
Points between straight segments are called Auto points. Freehand drawing, on
the other hand, generates segments connected with Corner points. Right
clicking on a line segment shows a menu indicating its type and allowing
changes (Fig. 7).
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Fig. 7 —PowerPoint (Microsoft) screen shot shows line drawing of left lung
and central airways. Straight lines (such as trachea) are drawn by clicking
and moving with Freeform tool. Curved lines (such as left mainstem bronchus)
are drawn by dragging with Freeform tool. Curved line made with this tool is
less smooth than line made with Curve tool. After right clicking inside
airways and selection of Edit Points, anchor points (vertexes) are displayed
as small squares. Right clicking over line segment brings up menu. Check mark
indicates current type of line segment (straight or smooth). Line type can be
changed with selection of another segment type from menu.
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Practice is essential for using these tools and commands effectively and
for grasping how the various techniques work. It is also advisable to improve
basic skills before proceeding to the more detailed discussion of drawing
techniques in part 2 [3].
Advantages and Limitations of Learning the Drawing Techniques of PowerPoint
The advantages and limitations of drawing one's own medical illustrations
with PowerPoint can be approached from the following three perspectives.
Medical Illustration on a Do-It-Yourself Basis
The importance of medical illustration is well recognized. Few radiologists
draw their own illustrations. This skill has clear advantages in comparison
with the alternatives [6]. In
most cases, radiologists hire professional medical artists or use
illustrations obtained from textbooks, journals, or the Internet. Medical
artists produce professional-grade illustrations. This source, however, is not
always free of shortcomings due to availability, cost, and sometimes long
turnaround time. In certain instances, ensuring that complex illustrations
deliver the anticipated result and message add to the cost in the form of the
extra time needed to brief artists properly and to repeatedly proof
illustrations. Using previously published illustrations also has problems,
such as copyright infringement, failure to optimally express the intended
meaning or idea, and the negative effect on the overall appearance of a
presentation when illustrations are derived from varied sources and diverse
artistic styles. Although drawing one's own medical illustrations has many
advantages, two major challenges preclude many radiologists from pursuing this
option. The challenges are the limited inherent or acquired artistic skills
and time constraints. These limitations, however, can be minimized through the
use of computers [7].
Using Computers for Drawing
Computers have been increasingly used to prepare digital illustrations,
even by professional medical artists
[8]. Several drawing software
packages are available. The advantages of using computers for drawing include
rapid generation of exquisite high-quality illustrations and easy editing with
a limited amount of manual artistic skill. In addition, the visual artistic
skills related to maintaining the aspect ratio are not crucial because
rendered radiologic images can be used as templates. Use of professional
software, however, poses challenges for radiologists. Most professional
software packages are expensive and complex. This complexity often
necessitates devoting considerable time to acquisition of skills.
Using PowerPoint Tools for Drawing
The first advantage of using PowerPoint tools to draw vector-based
illustrations is that medical illustrations can be designed without use of
separate complex professional software. Second, PowerPoint tools and
techniques are easy to learn and master. With practice, a person with limited
artistic skill can produce high-quality illustrations. These illustrations can
be used not only for presentations but also for publication. Publication is
discussed in Step 6 of part 2
[3]. Third, although they are
not as sophisticated as professional illustration programs, PowerPoint drawing
features can produce highquality illustrations. Fourth, imported drawings made
with illustration software into PowerPoint must be saved in bitmap format. The
advantages of vector illustration, such as ease of editing, versatility, and
resolution independence, are not available in the imported image. Unlike
illustrations imported from other programs, PowerPoint drawings maintain
vectorlike qualities in the slide. The versatility allows alteration and even
production of new illustrations by modification of previous ones. It also
allows application of other functions, such as animation, to one or more of
the objects forming an illustration. Such integration can greatly enhance the
educational value of a presentation. Finally, the ability to draw individual
objects makes it possible to merge illustrations with other elements of a
slide, such as radiologic images and charts.
Conclusion
Many radiologists are preparing their own presentations, but few are
involved in drawing their own illustrations. The newer versions of PowerPoint
have useful drawing tools that can enhance the educational value of a
presentation. The time devoted to learning the basics of vector drawing in
PowerPoint will reward radiologists with recognition as professionals whose
presentations are enhanced by superior illustrations and teaching
techniques.
Acknowledgments
Microsoft product screen shot(s) are reprinted with permission from
Microsoft Corporation.
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Abstract
Introduction
