Brightness Controls Research Articles

Subjective and objective evaluation of the impact of a quality assurance program on computer displays

Objective To examine impact of a quality assurance (QA) program for computer displays. Study design Five commercial off-the-shelf (COTS) displays (Dell Ultrasharp, 32-inch) were used in this study. The SMPTE test pattern was displayed on each monitor and three observers scored its pattern visibility. Screen luminance from select areas on the test pattern were measured with a Gossen light meter (MAVOLUX 5032B) to record maximum (Lmax), minimum (Lmin) and at 30%, 50% and 60% luminance. Next, display brightness and contrast were adjusted to enhance subjective perception of the SMPTE pattern. Screen luminance was measured as described above. Ambient illuminance was recorded at the center of the display. Results The ambient luminance was 0.05 cd/m2. The SMPTE pattern was adequately visualized on only 1 of the 5 displays. Overall, there was minimal variation in Lmin (0 to 0.3 cd/m2) and wide range in Lmax (59 to 339 cd/m2). The ambience ratio was 0.25 to 0.5 (recommended = 0.25). Display adjustment to optimally visualize the SMPTE contrast regions resulted in a decrease in the Lmax range (59 to 178 cd/m2, recommended maximum 250 cd/m2). Notably, brightness-contrast settings had to be customized for each display to optimally view the test pattern. Conclusions This study of high-end COTS displays used for radiologic diagnosis found that most displays required adjustment to optimally view the SMPTE test pattern. This underscores the need to establish a display QA program, as recommended by ADA/ANSI Standard 1094 and AAPM Report 270. Optimal visualization of the SMPTE test pattern required individualized display brightness and contrast controls that could not be simply applied to all monitors, emphasizing the need for periodic monitoring of individual displays. In ongoing studies, we are expanding our analyses to different display models and to ambient lighting settings that are more typical of chair-side settings. Statement of Ethical Review Ethical Review or exemption was not warranted for this study To examine impact of a quality assurance (QA) program for computer displays. Five commercial off-the-shelf (COTS) displays (Dell Ultrasharp, 32-inch) were used in this study. The SMPTE test pattern was displayed on each monitor and three observers scored its pattern visibility. Screen luminance from select areas on the test pattern were measured with a Gossen light meter (MAVOLUX 5032B) to record maximum (Lmax), minimum (Lmin) and at 30%, 50% and 60% luminance. Next, display brightness and contrast were adjusted to enhance subjective perception of the SMPTE pattern. Screen luminance was measured as described above. Ambient illuminance was recorded at the center of the display. The ambient luminance was 0.05 cd/m2. The SMPTE pattern was adequately visualized on only 1 of the 5 displays. Overall, there was minimal variation in Lmin (0 to 0.3 cd/m2) and wide range in Lmax (59 to 339 cd/m2). The ambience ratio was 0.25 to 0.5 (recommended = 0.25). Display adjustment to optimally visualize the SMPTE contrast regions resulted in a decrease in the Lmax range (59 to 178 cd/m2, recommended maximum 250 cd/m2). Notably, brightness-contrast settings had to be customized for each display to optimally view the test pattern. This study of high-end COTS displays used for radiologic diagnosis found that most displays required adjustment to optimally view the SMPTE test pattern. This underscores the need to establish a display QA program, as recommended by ADA/ANSI Standard 1094 and AAPM Report 270. Optimal visualization of the SMPTE test pattern required individualized display brightness and contrast controls that could not be simply applied to all monitors, emphasizing the need for periodic monitoring of individual displays. In ongoing studies, we are expanding our analyses to different display models and to ambient lighting settings that are more typical of chair-side settings.

Patterns in hammertone paints

Purpose The purpose of this study is to determine required paint and silicone proportions, their mixing rate and duration to eliminate the pattern problems caused by the misuse of silicone polymers in hammertone paints. Results of the findings aim at preventing raw material, manufacturing time and labour losses in hammertone paint production. Design/methodology/approach A paint formulation produced commercially was used. The effects of silicone proportion and mixing rate and paint and pigment density on the pattern formation within the paints, to which the spray painting method was applied, were investigated. Brightness controls of the produced paints were done, and the effect of the additive polymer on brightness was investigated. Photographs of paints for each practice were taken. Findings The most suitable silicone proportion and mixing conditions for the silver grey paints, in which Al non-leafing pigments were used, were calculated as 0.034-0.036 g/kg-paint and 15 s at 200 rpm, respectively. It was observed that the increase in pigment density increased required silicone proportion for the desired pattern. It was determined that mixing rate and duration were very significant in pattern formation, and that silicone decomposed and the pattern was disrupted in long-continued mixings. In addition, excess silicone use disrupted the pattern and decreased the paint brightness. Research limitations/implications This research was conducted for hammertone paints, which are industrial and self-patterned aluminium silvered decorative paints. The results can be used for hammertone paint production. Practical implications The results will enable manufacturers to produce hammertone paints more economically. Results can be used in the paint industry to produce such paint. Originality/value It is crucial to produce high-quality products using less raw materials in today’s industry, where the amount of raw materials is decreasing, and economical and reliable production is becoming increasingly important. When environmental impacts in the solvent-based paint industry are taken into consideration, paint production in shorter times is important for both workers’ and environmental health. As a result of this study, hammertone paints will be produced more economically by appropriate production conditions yet without any energy, raw material and time loss.

What Radiologists Want to See: Stack Mode Display in PowerPoint

The purpose of this article is to describe a stack mode viewer that is fully embeddable in PowerPoint and does not require external files. We developed a Web-based service named "RadViewer" that creates a Flash-based stack mode viewer and that is automatically embedded into PowerPoint. Features include mouse wheel and keyboard scrolling, zoom, cine loop, and brightness and contrast controls similar to those of a PACS workstation. Stack mode viewer created by RadViewer can be used in most radiology society meetings and conferences that use PowerPoint.

Data Preprocessing Circuit Designs and Analyses for Subsonic Cruise Missile Infrared Image Seeker

In this literature, a data pre-processing circuit designs and analyses for an infrared image seeker of a subsonic cruise missile are proposed. The flight speed of the missile is 250m/s. Therefore, automatic contrast control and automatic brightness control are usually needed to keep wanted contrast and brightness for best image properties in target recogni- tion and tracking; especially for the missile at the terminal approaching phase to prevent signal saturation. Signal satura- tion implies target lost. The major parameters of imaging systems for contrast and brightness controls include average, maximum and minimum of gray level of the whole picture in the sampling interval. Therefore, the overall system is a compli- cated nonlinear sampled-data control system. It is difficult to describe, analyze and design the system. In this literature, the over- all system is first decomposed into two linearized sampled-data control systems to get needed loop compensations, and verified by a special range-dependent testing signal to the overall system secondly. The controlled system is further verified by a thermal plate and real flight testing. Testing results give the proposed method can provide effective way to analyze and design the consid- ered system. INTRODUCTIONS Multiple sensors for ECCM are generally expected for missile homing systems. The first dual seeker application of the world for subsonic antiship missile is the HF-2 devel- oped in Taiwan. It includes a Radar seeker and an IR image seeker with data fusing algorithm. This application prompts the capability for ECCM from chaff jamming to RF seeker and thermal jamming to IR Image seeker. The problem for IR image seeker for the missile application is the thermal energy to the charge-coupled device (CCD) (1-3) is the fourth power of the reciprocal the distance between image seeker and thermal source; i.e.; missile and target. It needs faster automatic gain control (AGC) for contrast and auto- matic pedestal control (APC) for brightness (4-7) to keep best imaging properties for target recognition and tracking; especially for the missile at terminal approaching phase. Slower response for coping with thermal energy increasing will make the signal output be saturated; i.e., all white of full frame and will lost tracking centre point for missile guidance. It this literature, models for contrast, brightness and dy- namic signals are proposed to analyses and designs of the AGC and APC circuit loops. The AGC and APC are the pre- processing systems of the video signal. The block diagram considered is shown in Fig. (1). It includes thermal sensors, analog circuits, and microprocessor. The output of the proc- essed signal satisfies RS-170 video standard. The sensor elements for thermal imaging is 256�256 focal plane CCD(1-3), the gray level of each element is digitalized to be 256 states with 8bit A/D converter. Fig. (2) shows typical minimal and maximal gray level of a thermal picture. Analog circuit gives faster signal amplification in forward-loop. It needs 256� 256� 60�10Hz at least for 60Hz picture

Comparison between RVG UI sensor and Kodak InSight film for detection of incipient proximal caries

The purpose of this study was to compare the efficacy of the four combination modes of Trophy RadioVisioGraphy UI sensor (Trex-Trophy Radiology Inc., Marne-la-Valee, France) and Kodak InSight film (Eastman Kodak Co., Rochester, NY) for detecting proximal dental caries. Thirty extracted human upper premolars were selected. Of 60 surfaces, 25 had carious lesions in the form of small cavities, and the rest showed no evidence of caries as verified by a micro computed tomogram (micro CT; XCT Research SA+, Stratec Medizintechnik GmbH, Pforzheim, Germany). All teeth were radiographed with the paralleling technique (60kV, 40 cm focus-to-sensor distance). Four combination modes (high-resolution caries mode—HRC; high-sensitivity caries mode—HSC; high-resolution periodontal mode—HRP; and high-resolution endo mode—HRE) were used. Exposure was set at 0.12 sec for HRC, 0.08 sec for HSC, 0.16 sec for HRP, 0.12 sec for HRE, and 0.16 sec for the Kodak InSight film. The resulting images were evaluated by three oral radiologists. The same three observers evaluated the digital images, and were allowed to use the contrast and brightness controls in doing so. Possible differences in ROC curve areas among image modalities were assessed by the Friedman test. The mean ROC curve areas were 0.66±0.11 for HRC, 0.78±0.02 for HSC, 0.76±0.04 for HRE, 0.77±0.04 for HRP, and 0.71±0.09 for the Kodak InSight film. There were no statistically significant differences between HRC, HSC, HRE, HRP and the Kodak InSight film in terms of proximal caries detection. The four modes of RVG UI system are each a viable alternative to intraoral film for the detection of incipient dental caries.

Characterisation of a desktop LCD projector

A typical desktop LCD projector was characterised. Having determined the optimum settings of the brightness and contrast controls, measurements were made with a spectroradiometer to establish the additivity of the primaries, inter-channel dependence, colour gamut, tone scale, contrast, spatial non-uniformity, temporal stability and viewing angle variation. Four mathematical models were compared for their accuracy in predicting the colours generated by the display for arbitrary signal inputs. A new model was developed for the S-shaped electro-optical transfer function of the LCD device, and was extended to predict the anomalous colour tracking of the primaries.

Optimizing the constant-channel chromaticity and color gamut of CRT color displays by control of brightness and contrast levels

Before a CRT color display is calibrated, the levels of the brightness and contrast controls should be considered. These levels have different effects on the relationship between the chromaticity coordinates of the red-green-blue (RGB) channels and the voltage applied to the gun as well as on the color gamut. Using three different CRT color displays, we measured both these relationships as well as the color gamut for different combinations of brightness and contrast levels. With respect to the luminance range of the white point provided by each display, the results show that the assumption of constant-channel chromaticity of the RGB channels is more valid at medium- to low-brightness levels in combination with high-contrast levels. In addition, this assumption holds at high contrast and medium- to low-brightness levels, the color gamut being optimized at these combinations of levels, with regard to the size of the triangle of primaries-the maximum luminance of the display white point.

Hardware and Human Factors Issues for Military Automatic Brightness Controls

Electronic displays have replaced many mechanical displays in aircraft. The “glass” cockpit continues to advance. Electronic displays required adjustment of luminance (often referred to as brightness) and contrast as the ambient environment changes. Requiring pilots to manually control brightness creates additional pilot workload. Instead, automatic brightness controls (ABCs) have been suggested. The purpose of this paper is to summarize a research plan for the development of an ABC for military aircraft.

Exposure rates during special procedures with C-arm type fluoroscopic systems.

To test for regulatory compliance of free-in-air entrance air kerma rates (EAKR) in C-arm type fluoroscopic equipment, measurements are frequently made under minimum source-to-image receptor distance (SID) and at 300 mm from the image intensifier. However, this is not representative of normal patient geometry, and the automatic brightness controls on these units frequently increase tube output as SID increases. This study investigated effects of these circumstances on actual EAKRs. Typical patient geometries were observed and recorded for 23 consecutive body vascular procedures. EAKRs were measured under compliance and normal patient geometries with use of five modern C-arm type systems for special procedures. SIDs of 1 m were typical when rapid film changers were employed and the patient's entrance skin surface was typically 500 mm from the image receptor. Actual EAKRs were found to be up to 2.5 times those measured under compliance geometry. Actual patient geometries should be used to ensure correct estimates of EAKRs.

Multimode high definition and personal computer monitor chip set

A new family of devices to simplify the design of multimode computer displays has been developed. This cost-effective and highly integrated system has been developed for personal computer and high-definition CRT displays. The range of signals with which the chip set can operate includes TTL (transistor transistor logic) and/or analog video, and composite or separate H and V TTL level sync. The horizontal timebase has frequency agility, enabling it to lock over a range of 15.5 kHz to 50 kHz automatically. The analog video bandwidth is in excess of 50 MHz. Four integrated circuits are included in the family: one is used exclusively for TTL-to-analog video conversion, the other three are variants of the timebase/video circuit. The main system functions are TTL-to-analog conversion, DC video contrast and brightness controls, video cascode drivers for video output stages, automatic sync source and polarity control, a vertical oscillator and ramp generator, a frequency agile horizontal timebase, and programmable drivers for horizontal frequency-dependent power MOSFET switching.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Grey level linearising circuit for computer-interfaced display devices

An earlier paper by the authors on the linearisation of computer-interfaced display devices has described a radiometric procedure for quantifying device non-linearity and a software technique for using the data to linearise screen luminance with respect to display grey level. As the display non-linearity varies with the particular settings of the brightness and contrast controls, any change in these settings requires that the data used with the software also be modified. While it is possible to store data for a number of selected control settings, it would be more convenient if linearisation could be performed using hardware for all relevant settings of these controls. The electronic circuit described makes use of the same non-linearity data to achieve device linearity with the added advantage of increased flexibility of use. The circuit is suitable for connection immediately following the digital-to-analogue converter or video processor and provides two useful new controls. One of these determines the amount of non-linearity correction to be applied to the video signal, while the second enables screen contrast to be varied without affecting the linearity achieved. The standard brightness and contrast controls of the display device are left as initially preset and require no subsequent adjustment.

Gastrointestinal fluoroscopy: patient dose and methods for its reduction.

The aim of this study was to demonstrate a method which could be used to identify factors which contribute to the radiation exposure to patients from fluoroscopy during contrast examinations of the gastro-intestinal tract. Measurements of exposure made at the level of the X-ray tube collimator were extrapolated to obtain entrance exposure at the centre of the field and used as an index of the integral dose to the patient. Such data have heretofore been unavailable. The population studied included 65 patients ranging in age from 1 month to 21 years. In an initial study, median entrance exposure at the field centre for barium swallow examinations ranged from 0.98 to 1.7 mC/kg (3.8 to 6.6 R); barium meal: 1.9-5.7 mC/kg (7.4-22 R); barium meal with small bowel: 1.4-7.7 mC/kg (5.3-30 R); barium enema: 0.93-7.7 mC/kg (3.6-41 R). Gonadal dose, measured in males, ranged from undetectable to 0.71 mGy (71 mrad). The presence of contrast medium in the fluoroscopic field increased the exposure from a single 100 mm spot film, taken with automatic exposure control, by a factor of up to 16, and fluoroscopic exposure rate, using automatic brightness control, by a factor of 2 or more. We recommend modifications in the operation and design of fluoroscopic equipment, especially when fitted with brightness and exposure controls, for the reduction of patient exposure. Implementation of two modifications, a high/low dose switch, and a variable aperture iris diaphragm, reduced patient exposure from 1.4 to 3.4 times.

Terrain analysis from landsat using a color TV enhancement system

Visual interpretation of Landsat false-color composite imagery was employed to map terrain types on the Navajo Indian Reservation in northeastern Arizona and northwestern New Mexico. Three main difficulties were encountered in the visual analysis:(1) determination of the exact boundary positions; (2) repeatability of the boundary decisions over an area; and (3) discrimination among subtle tone differences associated with certain terrain type groupings. A simple image enhancement technique, based on a color television system was developed to make the visual analysis more accurate. A color TV camera was used to view the image and a color monitor used for the display. Image enhancement was achieved by use of the chroma, hue, contrast, and brightness controls on the monitor. The use of a zoom lens on the camera allowed rapid scale change and facilitated study of small areas of the image. By working directly from a color image, the technique obviated the need for separation positives with their attendant registration problems.

White-adapted photopic spectral sensitivity in human infants

Two human infants, 2–3 months of age, were tested by a forced-choice preferential looking technique, for the detection of chromatic and white stimuli superimposed on a white adapting field. Three adults were also tested by the method of adjustment in the same apparatus. Both adult and infant curves were relatively flat, as expected under white-adapted conditions. The adults were about 1 Lu. more sensitive than the infants in absolute terms, but the relative spectral sensitivity curves were similar. The results help to justify the use of adult spectral sensitivity curves as a first approximation to infant values, but do not eliminate the need for careful brightness controls in studies of infant color vision.

Responses of Neonates to Colored Stimuli

More recent investigations of infant color vision (Fagan 1974; Spears 1964) have used Munsell color papers which allow hue, saturation, and brightness levels to be specified. The major drawback of the Munsell colors for use in infant research is that the brightness controls are based on adult spectral sensitivity and there is evidence (Dobson 1976; Teller & Peeples, Note 1) that the spectral sensitivity of infants is different from that of adults. Specifically, Dobson (1976) has found that, compared with adults, infants show elevated sensitivity to stimuli in the short-wavelength end of the spectrum, but show similar sensitivity for long-wavelength stimuli. Thus, infant color research that includes Munsell colors from both

Photographic aspects of scanning electron microscopy.

Factors governing photographic image quality in the scanning electron microscope are discussed with particular reference to the commonly used EXA camera on the Cambridge Stereoscan IIa. It is shown that the small image on the medium speed film suffers considerable loss of information due to the turbid nature of the photographic emulsion. Inexpensive modifications to the oscilloscope camera supplied with the Stereoscan are described which enable the superior quality of a larger format to be utilized. Appropriate settings of the brightness and contrast controls of the image tube with respect to the photographic system is discussed and the results illustrated in a series of micrographs.

One Knob Picture Control

Since the beginning of color television, a main concern has been over the complexity of customer controls. It is difficult for the average layman and even for most engineers to properly set the contrast, brightness and chroma controls for optimum picture quality. Attempts have been made to solve this problem but costs were high and the solution left much to be desired. With the advent of integrated circuits, the solution is in hand. This paper describes a monolithic integrated circuit wherein a single adjustment controls the contrast, chroma amplitude, and brightness level of the TV receiver. This control adjusts both luminance and chrominance amplitude simultaneously. DC restoration of the video signal to black level eliminates need to readjust the brightness control. The unique DC restoration function is performed in the I.C.

A Two IC Pal Chrominance/Luminance System

The devices to be described perform in two 14 pin packages the necessary chrominance and luminance functions for the PAL system prior to chrominance demodulation. One device provides the necessary chrominance processing functions, while the other device combines luminance functions with manual chrominance control. Specifically, the chrominance IC contains the functions of sub-carrier regeneration, automatic chrominance control, H/ 2 generation and identification, color killer, and burst gating. The luminance IC provides DC operation of the contrast, saturation, and brightness controls, and the functions of beam current limiting and black level clamp.

Simplification of Viewer Brightness and Contrast Controls on Color TV Receivers

Simplification of Viewer Brightness and Contrast Controls on Color TV Receivers