Map: 'req-spec.GIF'

Requirement Specification

Describing a good product. Preliminary, elaborated, summary
The requirement specification described here is not the traditional contract between developer and buyer but an effort to describe a good product, developed within Utopia. It was used by the developers as not binding guidelines, see Cooperation agreement in Utopia Background. A preliminary, short specification of requirements on page make-up, image processing, work organization, work environment, human-computer interaction and training, was prepared 1983 in Utopia report no. 6 (in Swedish), elaborated in several reports (in Swedish) on the specific themes, e.g. image processing in Utopia report no. 14, with a new summary (in English) in Graffiti no. 7.
Evaluation of realism in the study at Aftonbladet
The study at Aftonbladet of the usability and functionality of the image processing system developed with the requirement specification as base can be regarded as an evaluation of the realism and usefulness of the image processing part of the requirement specification. Some of the results in Users' Experience and in Developers' Experience can be used as extensions/revisions of the requirement specification.

General requirements
New technology offered improvements of products and work
At that time, compared to conventional reprographical work, computer based image processing offered improved possibilities for image enhancement, image composition and easier adaptation of working practices to local and personal tastes. In addition, production and production planning could be integrated.
Quality in work and product
On the threshold of integrated full-page production the crucial question was: ''Can this technology be employed to improve quality of both work and product, and-if yes-how can it be done?" We assumed that it was possible and tried to outline how it could be done.

We tried to see computer based image processing from the point of view of the user and his/her conceptual world.

A use model is fundamental
A use model of a job is a description of the background and concepts which are necessary to carry out that job. Naturally, for most jobs several different models may be applied. Hence the model we will describe here is not the only one possible. However, it is important to discuss a model for the job before discussing how separate aspects of the job are to be carried out in detail.

A good model should facilitate:

  • insight towards the attainment of desired results;
  • discussions on image processing;
  • the understanding of commands to and information from the system;
  • comprehension and use of the system;
  • anticipation of the effect of an operation.

Tools for Skilled Workers
Generally speaking, it is not enough that the model itself is good. Tools for handling the model, i.e. for executing image processing, should be powerful and well designed. Image processing can be a difficult task, so the tools should be constructed to make the work easier. It is also important that the person executing the task is highly skilled.

Image processing involves the altering and/or the unifying of images. In image processing, graphic material, usually frames, can be inserted. To aid the worker in this task, he/she has a list of instructions or a description of the desired image, in either sketch, writing, or in oral form.

The result of each operation may be immediately evaluated ...
In traditional copy preparation the worker works directly with the images. However, he/she cannot always immediately see the results of his/her work. The new technology means that image processing is carried out with computers, and that each alteration of the image can be displayed directly on the screen. Hence computer based image processing both offers the sensation of working directly with the material, and the possibility of seeing the resulting image after each operation. If the result falls short of expectations, it should be easy for the worker to reconstruct the original image, i.e. undo an operation.
... and possibly undone
The work organization should be structured to support cooperation between journalists, who deal with the message and the news value, and graphic workers, who deal with the quality of the image and the graphic form.

Computer based image processing should offer a set of computer based tools to support the skilled graphic worker in his/her job to produce images of good quality.

To meet these requirements we propose a workstation where there is:

  • a scanner
  • an image processing station
  • equipment for proof production.

The Scanner
There should be scanners for prints as well as for transparencies at the workstation. To avoid the image taking up an unreasonably large amount of room in the computer's memory, certain adaptations of size, screen density, and contrast are carried out during the scanning.

Proofs
Proofs are necessary in the discussions between graphic workers, journalists, and customers on, for instance, cropping and composition. In many instances laser printer will often offer sufficient image quality.

The work station
Workstations for image processing and page makeup should be identical. It should be easy to switch between tasks. The workstation contains a worktable with room for paper, a keyboard, and a pointing device, e.g. a tablet with puck, and a display. All this should be easily adjustable for different people and for sitting as well as standing working position.

The image model
The images should be visible during image processing. These images may come directly from the scanner, or they may be fetched from a computer based archive, but they are often intermediate results between one or more original images and the final image. A menu of available operations and information on the state of the system should also be visible.

We recommend that the images to be processed should be placed on a desk together with the tools to place, process, and remove the images.

A mathematical formulation
This can be formulated in mathematical form. Let B be the intensity of some background. The image table has intensity 1 but the background can consist of a pile of images on the image table. Let I and T be the intensity and transparency of an image. Both usually varies with position in the image. The intensity, I1, of the image on the background is given by  I1 = T * B + (1 - T) * I. This model captures both transparent images (film) and opaque images (prints).

Conventional copy processing handles both prints and transparencies. The image model also contains a combination of these. Each image has a transparency layer indicating how much of the underlying surface is visible through the image (illuminating table or images lying underneath). A paper image is visible because different sections reflect light from the surrounding differently. In the image model this corresponds to the intensity layer indicating how much light various sections of the image emit. Several images may be placed on top of each other, resulting in a new image which looks like "the sum" of the layers of images.

The viewport concept
Both ends of the viewport are movable
We also propose that different sections of the desk are capable of being displayed in different windows on the display screen. Each window shows what can be seen through an imagined objective lens placed above the table. Thus it is possible to:
  • move the lens and alter its power;
  • move the window on the display and alter its size.


Tools for Image Processing
Traditionally, the worker's first step is to select the image he/she, will work with. It would therefore also be natural to choose the object before the operation in computer based image processing. There is always one current image. Most image operations affect the current image. An important tool is the box-a rectangle on the display; the form, size, and position of which can be easily changed. The box is used in many operations. The operation crop, for instance, removes those parts of the image which are outside the box.

It is especially important that the usual image processing operations such as cropping, scaling, tone correction, and rotation are well designed. The new technology opens up the possibility for innovative operations which are difficult to execute with conventional technology, for instance alterations in sharpness, screen removal, outlining, and retouching.


Problems
Reduction of turn-around time, cost and environmental problems
The major financial advantages of computer based image processing are that the costly intermediate results in the form of photographic silver images and the often time consuming and health hazardous photo chemistry can be removed. It thus entails a reduction of the period between the deadline and printing, as well as the reduction of the production time for advertisements.

Even though the new technology creates the basis for improved quality of work and product, the new potentials can, if they are not used correctly, give rise to new problems such as eye strain due to concentrated work with the display screen, and controversies in connection with copy right and confidence in the images.


Selected Requirements
In the following the original wording is used. Most of it have counterpart in contemporary applications such as Photoshop but with slightly deviating terminology.
  • Work procedures: Selected image(s) are shown in a life-like manner on the display, as are successive results of the operations.
  • The display screen: Must have a grey scale of at least 50 levels. Windows containing images, menu (operations), list of material, status information. Large enough to contain natural size images.
  • Human-Computer interaction devices: Keyboard and at least one pointing device with which to move the cursor about on the display. Undo, back-up, log and display the log, alter personal adjustment, adjourn and resume assignment.
  • Scanner: Electronic adjustment of corrections concerning size, tone, and mirroring must be possible during scanning. Resolution for magnifying slide-originals must be at minimum 10-fold.
  • Operations: The basic principle is that first the material is chosen and then it is decided what to do with it (operand before operation).
    • General tools: box, haircross, ruler, magnifying glass, reference pointing, histogram, densitometer.
    • Viewport: Create and remove, move on display, and across table, alter size and magnifying/deminishing factor.
    • Geometrical alternations: cropping, rotating, mirroring, scaling with the same or different scale factor horizontally and vertically.
    • Changes in tone: darker/lighter, grey tones, contrast, accentuating contours, softening, negative, drop out, density, medium tone alterations, tone alteration curve, tone line, screen removal.
    • Retouch: Follow contours, follow density, outline, choose pen, choose ink, retouch.
    • Allocation: move, move under, align with.
    • Composition: combine, add, copy.
    • Graphic material: lines, corners, frames, geometrical figures, free hand drawings.
    • Paper copies: proof printing (on printers), phototypesetting.
    • Image administration: retrieve, list, store, finish, up-date, re-start, dispatch for page make-up, terminate.
Work organization
The basic principles are: improve rather than depreciate skills and quality of product; integrated planning and execution; cooperation between the professional groups involved, work rotation; and decentralized decision making. The technology does not determine, but rather places limits on the content and work organization. That is why the following should be considered when evaluating a system:
  • Influence: on production volume, quality of product, work procedures, work load. working hours.
  • Control: possibility for contact betweeen colleagues, autonomous working groupps
  • Changes: in content, division and organization of page make-up, editing, advertisement layout, reproduction, service and maintenance etc.
Work environment
  • Workstations , keyboards, pointing devices, workchair, and worktable should be flexible and ergonomically designed.
  • Visual strain at the display: text is only displayed with at least 18 pixels between baselines, otherwise with grey lines corresponding to the words, sufficient contrast, sharp and square pixels, no flicker, reflexion, aberrations, or "ghost shadows".
Human-Computer interaction
The skilled graphic worker's control of the computer based on:
  • A natural and well-planned conceptual model of the system (a user model).
  • Command issuing via menus, forms, questions-answers, and with direct feedback.
  • Careful choice of cursors and colours.
  • Help and status information, including "logging" (history).
  • Updating and restarting without loss of information.
  • Possibility to create new tools (operations).
Training
  • Plans concerning the introduction of new tools must include training.
  • Training in the tools' functions must include "graphic datalogy", and supplier relates topics.
  • Must be based on a good user model which relates the new technology to the traditional skills.
  • Must include development and maintenance of system, work organization, work environment.
  • Teaching and material must be presented in the users' terminology and native language.



Latest update by Axel Henriksson 96-04-16