The application of two dimensional compression schemes to computer graphic display systems

Various picture compression schemes are proposed which achieve a reduction in the capacity of refresh storage by exploiting the redundancy in computer graphic pictures. Many different types of compression scheme have previously been considered, particularly for facsimile transmission of black and white pictures. This paper studies a compression scheme which takes into account the two dimensional nature of computer graphic pictures and which are digitized into more than two grey levels. A practical implementation of the method is also proposed for a real time computer display system.     

On the simulation of dynamic systems and their graphic display by hybrid computer

Starting from recent computer display technique developments, the paper illustrates some examples of graphic representation of dynamic systems for cases where the model is partly simulated on a parallel computer and partly described in a digital program, in order to take full advantage of the range of a hybrid computation unit.     

Socio-technical aspects of display units

The tree figure illustrates the concepts of this book. It addresses systems with displays of extremely social existence as compared with visual display units in the past. Given this recognition, the first chapter gives a socio-technical commentary on such systems using worldwide statistics. According to world statistics, some characteristic of the increasing use of display systems can be summarized in four items: appearance of liquid crystal displays, popularization of personal computer, diversification of display usage such as cell phones, and ergonomic consideration for elderly users. An example of the ethnic differences is illustrated.     

Exertion interfaces for computer videogames using smartphones as input controllers

As mobile phones become smarter and include a wider and more powerful array of sensory components, the opportunity to leverage those capabilities in contexts other than telephony grows. We have in particular identified those sensory capabilities as key components for modern user interfaces that can detect movement, actions and intentions to enrich human-computer interaction in a natural way. In this work, we present research around using smartphones as input controllers in the context of exertion videogames. We propose a conceptual framework that identifies the core elements of such interfaces, regardless of the underlying technological platforms, and provides a design pattern for their integration into existing videogames without having to change the game’s source code. We present a proof of concept implementation for the framework, with two smartphone input controllers, which using a soft button and accelerometer data, interface to a target-shooting exertion game played while exercising on a stationary bicycle. We present findings from a user experience evaluation.     

MTFA as a measure for computer display screen image quality

Computer display screen image quality is known to vary widely. Attempts have been made the world over at defining objective scales to better assess image sharpness and clarity. The experiments reported here were stimulated by the recent US adoption of MTFA≥5 as a minimum quality criteria. A series of ten hard-copy photographs and seven retrievable display screens were developed for a monochrome, cathode ray tube terminal that differed only in objective image quality. This series of display screen images was presented to 22 office workers, who were asked to provide a subjective image quality judgement in the form of a numerical scale ranking. The subjects were instructed to match the display screen with photographs that they estimated to be most comparable in image quality. Finally, the subjects were asked to specify what they considered to be the minimum acceptable visual quality. It was found that the subjects could accurately rank low and minimum quality display images and that their subjective visual quality judgement corresponded well with the objective MTFA quality scale. The minimum acceptable display quality specified by the office worker group corresponded to MTFA≥7, which is substantially higher than the US criteria and would disquality 40% of the video display terminals currently marketed in Sweden.     

The analogue computer in digital form

The paper considers in detail the feasibility of constructing a digital analogue computer (or differential analyser) on the basis of full-word or total transfer, rather than the incremental transfer which has been preferred in the past. After an analysis of the errors inherent in the integrating routine, and the possibilities for electronic patching, values are proposed for word length and sampling period. The paper concludes by suggesting a possible architecture for such a computer and discusses briefly the advantages it has to offer and the problems that must be faced in marketing it.     

Reliability of computer graphic images for visual assessment

This paper analyzes the use of computer graphics images as an architectural assessment tool. The characteristics of such images as an architectural simulation tool are discussed and their reliability as an assessment tool is evaluated and compared with that of traditional hand-generated perspective drawings. A specimen application, architectural simulation of a city renewal plan, is presented.     

The association between visual discomfort and the use of visual display units

This paper reports the results of a two-year survey of the visual problems associated with the use of visual display units (VDUs). The survey examined both discomfort levels and visual function, and asked whether there were differences in these measures between subjects who used a VDU in the completion of their tasks and controls who did not. In total, 202 subjects were examined. The main study examined four groups of which two, Data Preparation and Word Processing (WP) used a VDU in the completion of their tasks, while the other two, General Clerical and Typing (TY), did not. Subjective measures of visual discomfort and objective measures of visual function were taken at both the beginning and end of the day.

Two analyses were performed on the data; the first considered all four groups together, and the second directly compared the WP and TY groups—these two groups being considered well matched. The first analysis showed that statistically significant differences existed between the groups at the end of the day. However, differences were also shown between the groups at the beginning of the day, and when the measure 'change over the day' was used, no significant differences attributable to the VDU were found. The second analysis found no significant differences between the TY and WP groups, nor were any trends apparent.

A further study was done on ten subjects who alternated on a daily basis between using a word processor and a typewriter. No significant differences were found between the days using one and those using the other, confirming the above finding.

Whilst both optometric measures of visual function and reported visual discomfort did change over the day, we conclude we have no evidence lo support the idea that the VDU is in itself a causal factor of these changes to any greater extent than is the paper in a typewriter.     

The performance of computer input devices in a vibration environment

This study investigates the performance of a touch screen, mouse and trackball in a motion environment. A Stewart motion platform was used to generate a six-degree-of-freedom motion environment. Participants were placed in an environment where vehicle vibration was simulated. Tasks were used according to Fitts' Law to obtain the movement time, error rate, index of performance and throughput of each input device. The results showed that during static conditions, the touch screen gave the best results. However, in the vibration environment, the mouse gave the best results. The trackball is the worst of the three. The error rate and end-point variation tends to increase for the touch screen in the vibration environment.

Statement of Relevance: This study investigates the performance of a pointing device in a vibration environment. The results showed that during static conditions, the touch screen gave the best results. However, in the vibration environment, the mouse gave the best results. The track ball is the worst of the three. This research achievement can help human–computer interaction design in various dynamic environments such as in sea and land vehicles.     

基于单片机的安全显示系统的设计

该系统采用GPs技术和GSM网络.当老人或孩子遇到麻烦时,他(她)可选择自动或手动方式发出求救信号,系统将立刻启动GSM呼叫系统与信息中心或亲友建立连接,并采用主动和被动两种方式,将经度、纬度、声音、温湿度等安全状态信息实时传送到信息中心或者设定的亲友手机上,并在导航地图上显示出他(她)当前所在的位置.该设计中采用了"黑匣子"功能,完成了启动报警时最近20s的音频信息和位置信息的实时存储.     

Human factors aspects of pointing as an input technique in interactive computer systems

The use of pointing devices to input to interactive computer systems is increasing. This paper considers the human factors aspects of the use of a range of these devices. A distinction is drawn between direct and indirect devices. A number of aspects of pointing responses are discussed with reference to the experimental evidence: that pointing is non-linguistic, serial, involves gross motor movement and relies on visual feedback. The overall speed and the extent to which it is a natural form of response are also discussed. The paper ends with some conclusions about the suitability of different devices for different tasks.     

Experimental studies of control problem-solving processes using a graphic mnemonic display

Experiments were conducted to examine different cognitive strategies in control problem-solving using a graphic mnemonic display typical for the control rooms of complex technological systems in power, chemical, and metallurgical industries. The law of plurality of human work strategies (Vehda 1985) was used as a fundamental assumption for this study. Detailed studies of the cognitive strategies' characteristics are especially important for design of the information display, and further development of the theory of transformation dynamics (Venda and Venda 1991,1992). During experiments at a Moscow power plant three different strategies were identified (S_sy,S_w and S_p). Detailed follow-up experiments were conducted in the laboratory using a mock-up of a section of the power plant mnemonic display. Subject performance was analysed using eye movement registration, EEG recording, self-reporting, questionnaires, larynx myography, and time and error analysis. The follow-up experiments found three distinct strategies (S_ι, S_y and S_w). Laboratory assessment of information displays was validated only for the strategies S_y and S_w which were common for the real operators and subjects.     

A method of rotating areas on a raster scan graphic display

The method presented here permits an area of a picture held in a frame store to be rotated in the plane without recourse to a data structure or other picture definition. It is therefore suitable for use with digitized images and hand-drawn ones. Four techniques based on interpolation are compared and some performance figures are given. In addition, the effect of the computation on the appearance of the picture is discussed, a specific example being included.     

Ergonomic procurement guidelines for visual display units as a tool for progressive change

The Swedish Telecommunications Administration (STA) has put to gether a set of requirement specifications for general purpose Visual Display Units (VDUs), and in particular for VDUs to be used in telephone directory services and similar computer supported customer services. For VDUs based on Cathode Ray Tube technology, a rationale is presented for ergonomic requirements such as dark characters on a light background, a minimum refresh rate of 70 Hz, limits for acceptable levels of electric and magnetic field strengths, and full tilt, swivel and height adjustability of the VDU. Standardized measurement methods for e.g. legibility and resolution are needed in further developing the ergonomic procure ment process.     

MultiPoint: Comparing laser and manual pointing as remote input in large display interactions

We present MultiPoint, a set of perspective-based remote pointing techniques that allows users to perform bimanual and multi-finger remote manipulation of graphical objects on large displays. We conducted two empirical studies that compared remote pointing techniques performed using fingers and laser pointers, in single and multi-finger pointing interactions. We explored three types of manual selection gestures: squeeze, breach and trigger. The fastest and most preferred technique was the trigger gesture in the single point experiment and the unimanual breach gesture in the multi-finger pointing study. The laser pointer obtained mixed results: it is fast, but inaccurate in single point, and it obtained the lowest ranking and performance in the multipoint experiment. Our results suggest MultiPoint interaction techniques are superior in performance and accuracy to traditional laser pointers for interacting with graphical objects on a large display from a distance.     

Visual effects of the luminance surrounding a computer display

The luminance surrounding a computer display can potentially reduce visibility of the display (disability glare), result in sensations of discomfort (discomfort glare) and result in transient adaptation effects from fixating back and forth between the two luminance levels. The study objective was to measure the effects of surround luminance levels upon these functions in younger and older adults to determine recommended surround luminance levels. The younger age group comprised 20 subjects (mean age 27.9 years, range 23 – 39) and the older group 17 subjects (mean age 55.5 years, range 47 – 63). The central task was presented with luminance of 91 cd/M², tested surround luminance levels were 1.4, 2.4, 8.9, 25.5, 50, 91, 175, 317, and 600 cd/M². Disability glare was tested with low contrast (20%) visual acuity charts, transient adaptation was tested with a task that required regular fixation between the two luminance levels, discomfort was measured with a questionnaire after reading stories with different surround luminance levels, and preferred luminance was measured by method of adjustment. The surround luminance significantly affected transient adaptation (p < 0.0001), optimal performance occurred at 50 cd/M² and above for the young group and at 91 cd/M² and above for the older group. Neither low contrast acuity (disability glare) nor symptoms when reading were significantly affected by surround luminance. There was wide variation in preferred surround luminance; however, average preferred surround luminance was 86.9 cd/M² for the young group and 62.2 cd/M² for the older group, slightly below the central luminance of 91 cd/M². The effects of the surround luminance within the tested range are not large; however, the data show that the lowest surround luminance levels should be avoided and that surround luminance levels at or slightly below that of the central task are preferred.