Journal of Audiovisual Media in Medicine
ISSN: 0140-511X (Print) (Online) Journal homepage: http://www.tandfonline.com/loi/ijau19
The image database: pictures and computers Richard Morton To cite this article: Richard Morton (1992) The image database: pictures and computers, Journal of Audiovisual Media in Medicine, 15:2, 54-56, DOI: 10.3109/17453059209018342 To link to this article: http://dx.doi.org/10.3109/17453059209018342
Published online: 10 Jul 2009.
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Citing articles: 1 View citing articles
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=ijau19 Download by: [RMIT University Library]
Date: 11 May 2016, At: 03:27
Journal of Audiovisual Media in Medicine 1992; 15: 54-56
The image database: pictures and computers RICHARD MORTON
Downloaded by [RMIT University Library] at 03:27 11 May 2016
Information technology offers important new ways of using pictures for teaching in medicine. Methods for storing and delivering high quality images for computer-based learning systems are discussed.
Recent developments in image storage systems mean that the visual element so important in learning about diseases - can be more easily integrated into computer-based learning programmes in medicine. High resolution recording of pictures in a computer-accessible form requires large capacity storage systems. Much attention is focused on these systems at present, resulting in a plethora of techniques available or under development. It is only since the availability of ultra-high-density storage systems, particularly optical discs., that databases of high quality colour pictures have become possible. These systems are of two basic types, analogue and digital, and are summarized in Table 1. High-capacity storage systems analogue
Analogue systems record information as a continuous signal from a video source. Analogue optical discs (or videodiscs) work by shining a tightly focused laser beam on to a track of minute pits in a reflective plastic layer. There are two videodisc systems that can be used for holding image databases: Laservision and CRVdisc.
The video signal produced by a Laservision player can be displayed on a standard video monitor. In continuous play one side of a disc lasts 36 min, but it is as a recording medium for still frames - one side of a disc holds 54000 frames - and the fact that still frames can be replayed indefinitely and without any distortion, that make it of value in the context of picture archiving. This, together with the facility to access individual frames rapidly - it takes about 1 s to move from one frame to another anywhere on the disc - makes Laservision particularly valuable. Laservision discs are read-only - it is not possible to record on to the disc itself. The production of Laservision discs involves mastering on to 1-inch tape. The discs are then factoryproduced using a stamping master from which any number of discs can be pressed. Once mastered the discs can be mass produced at low cost.
CR Vdisc
About 3 years ago Sony introduced CRVdisc - a recordable, write once (recordable but not eraseable) laser videodisc. CRV stands for component recording video.
The CRVdisc recorder can be operated under computer control so that the exact frame number can be logged into a database as each frame is laid down. Like Laservision, the system records a standard analogue video signal. The discs have a lower capacity than LaserVision - 36000 frames each side as opposed to Laservision’s 54 000 - and the two systems are not compatible. CRVdisc is ideally suited to some specialist medical applications, e.g. it is used in eye clinics to store retinal images. It can also be used as an alternative to 1-inch tape for making masters for Laservision production*. As a system for the distribution of image databases it has the disadvantage that the replay equipment is expensive currently more than four times the cost of a Laservision player. Analogue images and computers
There are two ways of using analogue recorded images with computers. One is to display the images on a separate video screen, commands from the computer being used to control the disc player. The other is to digitize the video signal and display it on the computer screen. This requires a computer fitted with a video input board.
Laser Vision
Laservision was developed in the late 1970s by Philips and was the forerunner of all the optical storage systems that exist today. Its use for picture archiving in medicine dates back to 19801.
Richard Morton MSc, FRPS, AIMI is Director of Graves Educational Resources, 220 New London Road, Chelrnsford, Essex, UK.
@ 1992 Butterworth-Heinernann Ltd 0140-51lX/92/020054-03
Table 1. High capacity storage systems suitable for holding image data
Analogue video
Digital
Laservision
CRVdisk
CD
Magnetic disk
54K frames
36K frames
650 M bytes
100 M bytes or more
Read only
WORM*
Read only also WORM*
Read write
* Write Once Read Many
High-capacity storage systems digital
Downloaded by [RMIT University Library] at 03:27 11 May 2016
In digital systems the information making up a picture is broken down into binary digits (bits) so that it can be stored and processed in a computer. The storage in a computer of data made up of numbers and letters is straightforward, and vast quantities of this kind of information can be held. For example, a typical microcomputer with an integral 40 megabyte hard disk can hold the equivalent of about 16000 pages of data. By contrast the number of bytes (1 byte is generally 8 bits) required for high-resolution colour pictures is so great that such a machine could only store four of these (Figure 1).
Resolution
The quality of analogue video pictures, such as those recorded on videodisc (or for that matter on videotape) is dependent mainly on the resolution of the video camera used to capture the pictures, and the bandwidth of the recording medium. On the other hand the quality, or resolution, of digitally recorded pictures depends on the number of bytes devoted to each frame and the system used for capturing and displaying them. About 1 megabyte is needed to store, in digital form, all the information contained in a single frame of high-quality video. However, a frame
2.5K bytes
of videotape is of much lower resolution than a frame of film. To record digitally the full resolution of a 35-mm frame of a 100 ASA film requires over 10 megabytes. A special scanner is used for recording at this resolution.
age system is needed to hold them. One solution is to store pictures on a standard magnetic hard disk. However, for images to be stored in large numbers, and to be transportable between machines, one of the compact disc formats is the usual choice.
Compression
In order to overcome the storage requirements for image data, techniques have been developed whereby the data are compressed for recording and decompressed for display. This is a complex subject which goes beyond the scope of this article, except to say that compression in excess of 1OO:l is possible. Compression has particular relevance to the digital recording of full-motion video where enormous amounts of data have to be read and processed at high speed. Digitizing
Before picture information in the form of a video signal can be held in a computer-readable form it must be digitized using a digital video adapter, a board fitted inside the computer which accepts and digitizes a video signal so that it can be processed and stored.
Compact discs
Compact Disc - Read Only Memory (CD-ROM) discs have been used for some time as a read-only medium for the distribution of large databases, and a CD drive is now a widely available computer peripheral. The capacity of a CD-ROM is about 650 megabytes, equivalent to something like a quarter of a million pages of text. CD-ROM represents an important medium for the distribution of image databases. Several new CD-based systems designed specifically to handle image data have recently become available or are under development. Most of them have been produced to meet the needs of so-called 'multimedia' systems, i.e. computer systems that can deliver sound, video, graphics and text. The following is a brief survey of these systems.
High-capacity storage
Photo CD
Once a number of pictures has been digitized a suitable high-capacity stor-
This is one of the most interesting of the new CD formats in the context of still image storage. A consumer product due to be launched in 1992 by Kodak, its primary purpose is to provide a storage and display system for photographs. When films are processed and printed in the normal way it will be possible to have the images scanned and recorded on to this special kind of CD-ROM. Photo CD is a write-once medium and further pictures may be added at a later date, when subsequent films are processed. The disc will enable pictures to be viewed on a television set using a Photo CD player or a CD-I player (see below). Photographic quality reprints can be made directly from the disc using a thermal printer linked to a computer. A special scanner has been developed by Kodak for use with the Photo CD system. It is capable of recording at a resolution of 18 megabytes - equal to the resolution of a high-quality silverbased original. It will be possible to record about 100 frames (with compression at 4 : l ) on one Photo CD at a resolution equal to the original photograph.
10 OOOK bytes
Figure 1. One high quality colour picture requires 4000 times more storage capacity than a page of text.
The Journal of Audiovisual Media in Medicine (1992) Vol. 15INo. 2
55
CD-l
Compact disc interactive is a system developed jointly by Philips, Matsushita and Sony which uses a special set of computer chips to control the replay of video, text and graphics information from a specially recorded CD-ROM. CD-I is due for release on to the domestic market in Europe in 1992. The CD-I player contains its own microcomputer and connects to an ordinary television set. It is operated from a remote control.
DVI
Digital video interactive uses add-on boards in a standard microcomputer to allow the direct input of video and other signals which are compressed and stored on the computer’s hard disk (or exported to other storage systems).
easier to make high quality images an integral part of computer-based learning programmes. At the same time a number of easy to use authoring packages for computer-based learning, the other vital component in the production of effective courseware, is also being developed. As resources become more widely available there is every reason to expect that the power and flexibility of the computer will become more effectively harnessed, on a much wider scale, to the educational needs of the healthcare professions.
Image databases- the future
CD-ROM XA
Downloaded by [RMIT University Library] at 03:27 11 May 2016
images and is operated with a remote control. New developments in CD technology include a write many read many system (WMRM).
Compact disc read only memory extended architecture is a system which has been developed to give some of the functions of CD-I using a standard computer with CD-ROM drive rather than a special player.
CDTV
Commodore Dynamic Total Vision is another CD-based multimedia system aimed at the domestic market. Like CD-I it uses a television set to display
As bigger and cheaper mass storage systems and better compression techniques are developed it will be possible to supply fully illustrated computer-based training programmes on low cost delivery systems. In the near future it may be possible, using a new technique known as fractal compression, to store large numbers of pictures on floppy disks.
References
Conclusions
1. McArthur JR. Conventional and hightechnology teaching methods for educating health professionals in developing nations. J Audiovis Media Med 1982; 5 21-6.
Recent improvements in image storage techniques mean that it is becoming
2. Morton R. Desktop videodisc mastering. Viewfinder 1991; 12: 12-13.
A BACKWARD GLANCE Twenty-five years ago From Medical and Biological Illustration (1966) 16: 259 Fibre Optics in Injection Needle The Jenaer Glaswerk Schott and Gen. of Mainz, Germany, have developed many new and interesting examples of the practical use of fibre optics. Outstanding amongst these examples shown recently is a minute injection needle containing a bundle of 5000 fibres allowing visualization and possible photomicrography of the internal structure of muscle and other tissues. Where does the light come from . . . ? CHRONOS
56
Morton
ISSN: 0140-511X (Print) (Online) Journal homepage: http://www.tandfonline.com/loi/ijau19
The image database: pictures and computers Richard Morton To cite this article: Richard Morton (1992) The image database: pictures and computers, Journal of Audiovisual Media in Medicine, 15:2, 54-56, DOI: 10.3109/17453059209018342 To link to this article: http://dx.doi.org/10.3109/17453059209018342
Published online: 10 Jul 2009.
Submit your article to this journal
Article views: 7
View related articles
Citing articles: 1 View citing articles
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=ijau19 Download by: [RMIT University Library]
Date: 11 May 2016, At: 03:27
Journal of Audiovisual Media in Medicine 1992; 15: 54-56
The image database: pictures and computers RICHARD MORTON
Downloaded by [RMIT University Library] at 03:27 11 May 2016
Information technology offers important new ways of using pictures for teaching in medicine. Methods for storing and delivering high quality images for computer-based learning systems are discussed.
Recent developments in image storage systems mean that the visual element so important in learning about diseases - can be more easily integrated into computer-based learning programmes in medicine. High resolution recording of pictures in a computer-accessible form requires large capacity storage systems. Much attention is focused on these systems at present, resulting in a plethora of techniques available or under development. It is only since the availability of ultra-high-density storage systems, particularly optical discs., that databases of high quality colour pictures have become possible. These systems are of two basic types, analogue and digital, and are summarized in Table 1. High-capacity storage systems analogue
Analogue systems record information as a continuous signal from a video source. Analogue optical discs (or videodiscs) work by shining a tightly focused laser beam on to a track of minute pits in a reflective plastic layer. There are two videodisc systems that can be used for holding image databases: Laservision and CRVdisc.
The video signal produced by a Laservision player can be displayed on a standard video monitor. In continuous play one side of a disc lasts 36 min, but it is as a recording medium for still frames - one side of a disc holds 54000 frames - and the fact that still frames can be replayed indefinitely and without any distortion, that make it of value in the context of picture archiving. This, together with the facility to access individual frames rapidly - it takes about 1 s to move from one frame to another anywhere on the disc - makes Laservision particularly valuable. Laservision discs are read-only - it is not possible to record on to the disc itself. The production of Laservision discs involves mastering on to 1-inch tape. The discs are then factoryproduced using a stamping master from which any number of discs can be pressed. Once mastered the discs can be mass produced at low cost.
CR Vdisc
About 3 years ago Sony introduced CRVdisc - a recordable, write once (recordable but not eraseable) laser videodisc. CRV stands for component recording video.
The CRVdisc recorder can be operated under computer control so that the exact frame number can be logged into a database as each frame is laid down. Like Laservision, the system records a standard analogue video signal. The discs have a lower capacity than LaserVision - 36000 frames each side as opposed to Laservision’s 54 000 - and the two systems are not compatible. CRVdisc is ideally suited to some specialist medical applications, e.g. it is used in eye clinics to store retinal images. It can also be used as an alternative to 1-inch tape for making masters for Laservision production*. As a system for the distribution of image databases it has the disadvantage that the replay equipment is expensive currently more than four times the cost of a Laservision player. Analogue images and computers
There are two ways of using analogue recorded images with computers. One is to display the images on a separate video screen, commands from the computer being used to control the disc player. The other is to digitize the video signal and display it on the computer screen. This requires a computer fitted with a video input board.
Laser Vision
Laservision was developed in the late 1970s by Philips and was the forerunner of all the optical storage systems that exist today. Its use for picture archiving in medicine dates back to 19801.
Richard Morton MSc, FRPS, AIMI is Director of Graves Educational Resources, 220 New London Road, Chelrnsford, Essex, UK.
@ 1992 Butterworth-Heinernann Ltd 0140-51lX/92/020054-03
Table 1. High capacity storage systems suitable for holding image data
Analogue video
Digital
Laservision
CRVdisk
CD
Magnetic disk
54K frames
36K frames
650 M bytes
100 M bytes or more
Read only
WORM*
Read only also WORM*
Read write
* Write Once Read Many
High-capacity storage systems digital
Downloaded by [RMIT University Library] at 03:27 11 May 2016
In digital systems the information making up a picture is broken down into binary digits (bits) so that it can be stored and processed in a computer. The storage in a computer of data made up of numbers and letters is straightforward, and vast quantities of this kind of information can be held. For example, a typical microcomputer with an integral 40 megabyte hard disk can hold the equivalent of about 16000 pages of data. By contrast the number of bytes (1 byte is generally 8 bits) required for high-resolution colour pictures is so great that such a machine could only store four of these (Figure 1).
Resolution
The quality of analogue video pictures, such as those recorded on videodisc (or for that matter on videotape) is dependent mainly on the resolution of the video camera used to capture the pictures, and the bandwidth of the recording medium. On the other hand the quality, or resolution, of digitally recorded pictures depends on the number of bytes devoted to each frame and the system used for capturing and displaying them. About 1 megabyte is needed to store, in digital form, all the information contained in a single frame of high-quality video. However, a frame
2.5K bytes
of videotape is of much lower resolution than a frame of film. To record digitally the full resolution of a 35-mm frame of a 100 ASA film requires over 10 megabytes. A special scanner is used for recording at this resolution.
age system is needed to hold them. One solution is to store pictures on a standard magnetic hard disk. However, for images to be stored in large numbers, and to be transportable between machines, one of the compact disc formats is the usual choice.
Compression
In order to overcome the storage requirements for image data, techniques have been developed whereby the data are compressed for recording and decompressed for display. This is a complex subject which goes beyond the scope of this article, except to say that compression in excess of 1OO:l is possible. Compression has particular relevance to the digital recording of full-motion video where enormous amounts of data have to be read and processed at high speed. Digitizing
Before picture information in the form of a video signal can be held in a computer-readable form it must be digitized using a digital video adapter, a board fitted inside the computer which accepts and digitizes a video signal so that it can be processed and stored.
Compact discs
Compact Disc - Read Only Memory (CD-ROM) discs have been used for some time as a read-only medium for the distribution of large databases, and a CD drive is now a widely available computer peripheral. The capacity of a CD-ROM is about 650 megabytes, equivalent to something like a quarter of a million pages of text. CD-ROM represents an important medium for the distribution of image databases. Several new CD-based systems designed specifically to handle image data have recently become available or are under development. Most of them have been produced to meet the needs of so-called 'multimedia' systems, i.e. computer systems that can deliver sound, video, graphics and text. The following is a brief survey of these systems.
High-capacity storage
Photo CD
Once a number of pictures has been digitized a suitable high-capacity stor-
This is one of the most interesting of the new CD formats in the context of still image storage. A consumer product due to be launched in 1992 by Kodak, its primary purpose is to provide a storage and display system for photographs. When films are processed and printed in the normal way it will be possible to have the images scanned and recorded on to this special kind of CD-ROM. Photo CD is a write-once medium and further pictures may be added at a later date, when subsequent films are processed. The disc will enable pictures to be viewed on a television set using a Photo CD player or a CD-I player (see below). Photographic quality reprints can be made directly from the disc using a thermal printer linked to a computer. A special scanner has been developed by Kodak for use with the Photo CD system. It is capable of recording at a resolution of 18 megabytes - equal to the resolution of a high-quality silverbased original. It will be possible to record about 100 frames (with compression at 4 : l ) on one Photo CD at a resolution equal to the original photograph.
10 OOOK bytes
Figure 1. One high quality colour picture requires 4000 times more storage capacity than a page of text.
The Journal of Audiovisual Media in Medicine (1992) Vol. 15INo. 2
55
CD-l
Compact disc interactive is a system developed jointly by Philips, Matsushita and Sony which uses a special set of computer chips to control the replay of video, text and graphics information from a specially recorded CD-ROM. CD-I is due for release on to the domestic market in Europe in 1992. The CD-I player contains its own microcomputer and connects to an ordinary television set. It is operated from a remote control.
DVI
Digital video interactive uses add-on boards in a standard microcomputer to allow the direct input of video and other signals which are compressed and stored on the computer’s hard disk (or exported to other storage systems).
easier to make high quality images an integral part of computer-based learning programmes. At the same time a number of easy to use authoring packages for computer-based learning, the other vital component in the production of effective courseware, is also being developed. As resources become more widely available there is every reason to expect that the power and flexibility of the computer will become more effectively harnessed, on a much wider scale, to the educational needs of the healthcare professions.
Image databases- the future
CD-ROM XA
Downloaded by [RMIT University Library] at 03:27 11 May 2016
images and is operated with a remote control. New developments in CD technology include a write many read many system (WMRM).
Compact disc read only memory extended architecture is a system which has been developed to give some of the functions of CD-I using a standard computer with CD-ROM drive rather than a special player.
CDTV
Commodore Dynamic Total Vision is another CD-based multimedia system aimed at the domestic market. Like CD-I it uses a television set to display
As bigger and cheaper mass storage systems and better compression techniques are developed it will be possible to supply fully illustrated computer-based training programmes on low cost delivery systems. In the near future it may be possible, using a new technique known as fractal compression, to store large numbers of pictures on floppy disks.
References
Conclusions
1. McArthur JR. Conventional and hightechnology teaching methods for educating health professionals in developing nations. J Audiovis Media Med 1982; 5 21-6.
Recent improvements in image storage techniques mean that it is becoming
2. Morton R. Desktop videodisc mastering. Viewfinder 1991; 12: 12-13.
A BACKWARD GLANCE Twenty-five years ago From Medical and Biological Illustration (1966) 16: 259 Fibre Optics in Injection Needle The Jenaer Glaswerk Schott and Gen. of Mainz, Germany, have developed many new and interesting examples of the practical use of fibre optics. Outstanding amongst these examples shown recently is a minute injection needle containing a bundle of 5000 fibres allowing visualization and possible photomicrography of the internal structure of muscle and other tissues. Where does the light come from . . . ? CHRONOS
56
Morton
