Imaging Toolkits
Imaging toolkits enable fast-cycle development of
image-enabled applications. Most
imaging functions that are required are immediately
ready for use in imaging toolkits.
However, besides purchasing a commercial imaging
toolkit, there are some options
available.
The first step in developing an image-enabled
application is to decide how the image
decoder is to be implemented. The options are basically:
1. Implement your own image decoder (coding from ground-up)
2. Using a standard Visual Basic control
3. Using an imaging toolkit (recommended)
Implementing Your Own Image Decoder
The main benefit of this option is obvious - it's free
(at least from a financial viewpoint).
However,
significant time, effort and expertise is required to
understand each individual
image format and then code
the engine. For the majority of the programmers, this
option, although possible, is not practical.
For the strong and the persevering, image format
specifications are public domain
information and are
available for download. For a start, to popular
specifications (JPG and TIFF) can be downloaded from
http://www.jpeg.org
and http://www.libtiff.org.
Another
popular format is the GIF image format. However,
the technology is currently patented by
Unisys
Corporation*. Although this international patent has
expired in most regions, it is
still in force in the
United States (expiring in April 2004).
Using Standard Visual Basic Controls
Visual Basic ships with 2 standard controls - the PictureBox
control and the Image
control. However, the functionality provided by both
these control are very limited and are mainly for image
display only.
Supported image formats include JPEG, GIF, WMF, EMF, BMP
and ICO.
Using an Imaging Toolkit
There are many imaging toolkits available. The Ilixis
Developer's Corner is only
introducing a subset of very
practical imaging toolkits that will suit the needs of the vast
majority of developers.
Imaging toolkits can generally be classified under 2
categories:
1. Free imaging toolkits
2. Professional imaging toolkits
Free Imaging Toolkits
The 'FREE' Kodak/Wang Image OCX
Controls (Imaging for Windows) that ship with
Windows 95, 98, NT and 2000 is a very popular toolkit
set for
developing image-enabled applications. This toolkit
consists of 4 OCX controls - Kodak Image Admin Control (ImgAdmin.ocx),
Kodak Image Edit Control (ImgEdit.ocx), Kodak Image Scan
Control (ImgScan.ocx) and Kodak Image Thumbnail Control
(ImgThumb.ocx).
* Kodak bought over Imaging for Windows from Wang
Laboratories and subsequently changed the name of the
controls from Wang to Kodak. Kodak has since sold Imaging for
Windows to eiStream, Inc.
Another popular 'FREE' toolkit is the Microsoft
Office Document Imaging 2003 (MODI) Object Model and the
Viewer OCX Control that ships with Microsoft Office
2003. The version that ships with Microsoft Office XP
does not allow automation. This toolkit contains both an
Object Model and a Viewer OCX control.
Another 'FREE' imaging toolkit is the Windows
Image Acquisition (WIA) Library that is available
for developers who
need to develop image-enabled applications for Windows
ME and XP. WIA extends beyond imaging to include video
functionality.
The 'FREE' imaging toolkits described above contain limitations that may
not be acceptable for some projects.
Two main limitations are:
1. Distribution - the libraries are not supported across
all Windows platforms. In the case
of Microsoft Office Document Imaging
2003 (MODI) Object Model and Viewer OCX
Control, Microsoft Office 2003 is a
pre-requisite.
2. Functionality is limited - e.g. filtering and
advanced image manipulation functionality is
not available in both libraries.
Commercial Imaging Toolkits
Commercial imaging toolkits provide advanced functionality and
support across all
image-related disciplines -
displaying; enhancing and manipulation; annotation;
scanning;
conversion; printing; etc. Applications
developed using commercial imaging toolkits can
normally be
deployed across all Windows platforms.
Using a commercial imaging toolkit can potential save
a lot of coding time as almost all
imaging functionality
that may be possibly needed is already ready and
available for use.
The developer simply needs to call
the functionality. If the developer is familiar with
programming and imaging concepts, it may even be
possible to develop a reasonably
complex application
within a couple of days.
There are currently many commercial imaging toolkits
available. Simply go to Google and
type in "imaging
toolkit" for a long list of imaging toolkits. The Ilixis
Developer's Corner
provides tips and guidelines
to choosing a commercial imaging toolkit.
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