Showing papers on "Image quality published in 1978"

Optical image quality in the peripheral retina.

Abstract: A double-pass, photoelectric, ophthalmoscopic method was used for objective study of the variation in image quality across the retina in terms of the reflected image of a fine line, the line-spread function. Radial and tangential line-spread functions have been studied with active and paraly

A Study of High-Definition TV System in the Future

Abstract: The results of our studies of high-definition television system are described concerning picture quality, signal standard and transmission system.

Evaluating the efficient of imaging processes

Abstract: This review describes the techniques which are used to evaluate the properties of the recorded image. These techniques are described from the viewpoints of Fourier analysis, quantum efficiency, and information theory. An analysis is made of the mechanisms of conventional silver halide processes which control their imaging efficiency and image quality. Some examples of the methods of image evaluation are given for practical problems involving X-ray images, electronographic cameras and image intensifiers in astronomy, and for the electrophotographic process.

Halftone images: Spatial resolution and tone reproduction*

Abstract: The halftone technique, which converts a continuous-tone picture into a binary image, is examined. A halftone screen function is used to specify configurations of binary image elements; their area determines the local average image irradiance and information about the spatial image irradiance variations is relfected in their boundaries. A halftone ring geometry is suggested to improve spatial image resolution. Experiments are reported to verify this prediction.

Comparison of image restoration methods.

Abstract: Three image restoration methods are compared in a variety of blur and noise conditions. Both numerical and subjective data are evaluated. It is demonstrated that, in certain conditions, one restoration method is preferable to others.

An evaluation and comparison of several measures of image quality for television display

Abstract: : Television display systems are currently widely used for many image transmission applications other than home entertainment. For many military and commercial uses the quality of the displayed imagery is critical with respect to its effect on observer performance. This dissertation investigates 19 figures of merit (FOM's) that have been proposed as measures of television image quality. Target detection and target recognition study was implemented to determine which of the 19 FOM's correlated highest with performance. The study employed a 525 line, 60 Hz field rate television display system with 2:1 interlace of fields. Nine different display quality conditions were investigated using all combinations of three contrast ratios (50:1, 50:5 and 50:15) and three video bandwidths (6.0 MHz, 1.0 MHz, and 0.4 MHz). Noise was not varied. Three FOM's stood out as promising indicators of display quality and observer performance. The highest correlating FOM was the log band-limited modulation transfer function area (log BLMTFA) closely followed by the just-noticeable difference area-log (JNDA-log), 1/2 cpd and the JNDA-log, 2 cpd.

Dynamic reference for an image quality control system

Abstract: A system for checking copy quality variables within the image area of an electrophotographic machine. During a test cycle, quality is checked by producing sample test areas within the photoconductor image area ordinarily used for producing copies. Reflectance measurements are made on the sample test areas and compared to a dynamically floating reference achieved by a reflectance measurement from a cleaned portion of the photoconductor within the image area. The testing circuit is balanced so that the same reflectance voltage should be generated whether the single reflectivity-sensing device is viewing a sample test area or a cleaned reference area. The system checks for quality variables such as toner concentration, image voltage and an abnormally low reflectance photoconductor and provides a partial check on its own fault-free condition during periods when it is not in use.

The PROM - A Status Report

Abstract: The PROM is a solid-state, rapidly recyclable, image storage device having a number of applications in image and signal processing. Some of its important characteristics include 1/10-wave optical surface quality, 100-1p/mm three-bar resolution, 10 ergs/cm2 light sensitivity, and image plane contrast of 10 4 :1. One of the unique features of the PROM is that the bias level of stored patterns can be adjusted through application of an external voltage, resulting in image contrast inversion or enhancement. This same operation (baseline subtraction) is used to null the zero order in an optical Fourier transform, achieving a Fourier plane signal-to-noise ratio approaching 106:1. This paper reports on the current status of this device and a number of applications for which it has been tested in several areas of image and signal processing. Results are shown for coherent optical processing by computer-controlled Fourier plane filtering and real-time image correlation, and signal processing systems are described which couple the PROM with an acousto-optic raster recorder to perform spectrum analysis and correlation on radio frequency signals.

Image Noise And Smoothing In Computed Tomography (CT) Scanners

Abstract: The question of what spatial frequency response gives optimum image quality in computed tomography (CT) images is studied. We have developed a technique for smoothing these images by using a modified back projection filter with attenuated high frequency response. The results are images with a blurred appearance but dramatically reduced image noise. On processing raw data from the EMI head scanner in this way, grey and white matter distributions are clearly visualized with no increase in radiation dose. These results are analyzed in terms of the Weiner spectrum and correlation properties of CT noise. In particular, a "noise equivalent aperture" is defined in a way analogous to that of Schade. It is shown that the prediction of the simple Rose model of noise sampling cannot explain the improvement produced by smoothing, even when the correlated character of the noise is taken into account.

A multiple frequency array for improved diagnostic imaging

Abstract: Cost and complexity of phased array diagnostic ultrasound imaging systems is related to the number of parallel channels during both transmit and receive. If the total numberofa ctive elements within a given aperture is reduced so that fewer parallel channels are required, grating lobes may result if the spacing of elements within the array is greater than one-half wavelength. These grating lobes may produce image ambiguities in the form of multiple images and reduced dynamic range. These grating lobes can, however, be reduced if transducers of large bandwidth are utilized. A novel broadband array is described which consists of two transducer arrays of different frequencies (one at 1.5 MHz, the other at 2.5 MHz) mounted one above the other. This method of construction avoids the usual compromise between sensitivity and bandwidth. Experiments indicate a reduction of 5 dB in the off-axis response in the transmit operation when compared to a single frequency array (2.5 MHz) with similar dimensions (16 elements within a 19.7-mm aperture). The routine diagnostic utilization of this array resulted in improved image quality in terms of reduced image artifacts and improved contrast as well as better target acquisition.

Ultrasonic diagnosing device

Abstract: PROBLEM TO BE SOLVED: To draw a clear image by reducing an image quality deterioration at the deep section of a subject SOLUTION: Ultrasonic wave are transmitted in the same direction by driving an ultrasonic wave transducer 21 which transmits/receives ultrasonic waves by driving pulses of different voltages by a transmitting section 1 Then, the fundamental wave of the reflected signal is received by a fundamental wave- receiving section 3, and at least one of the received signals of the fundamental waves based on the driving pulses of the different voltages is coefficient- multiplied by coefficient circuits 41 and 42 Then, a difference between both signals is obtained by a difference circuit 43 By this constitution, the influence of a side lobe is eliminated, and the image quality at the deep section of the subject is greatly improved, and a clear image can be drawn

Picture processing system

Abstract: PURPOSE: To improve a picture quality and a transmission efficiency by reading data suitably for original patterns. CONSTITUTION: Data read in by scanner 1 is stored in analogue memory 2, and simultaneously, this data is subjected to sampling by sampling gate 3 and is converted to quarternaries by A/D converter 4; and if data is discriminated as the intermediate level by level decoder 5, it is counted by counter 6. After the completion of the scan of one-line components, the output is decoded by count decoder 7, and an analogue image is discriminated if data is over a prescribed value. Then, data stored in analogue memory 2 is outputted to plotter 10 by multiplexer 9. If data is discriminated as a digital picture, data in analogue memory 2 is inputted to plotter 10 through multiplexer 9. COPYRIGHT: (C)1979,JPO&Japio

Power-Law Stimulus-Response Models for Measures of Image Quality in Nonperformance Environments

Abstract: A new method for relating subjective and objective image data measures is proposed in power-law stimulus-response models, which have been successfully employed in other problems in experimental psychology but not in image quality models. The results of a viewing experiment to explore this model are presented.

Suspect identification following exposure to sketches and Identi-Kit composites

Abstract: A facial recognition study explored the utility of two common image generation techniques--sketches and Identi-kit composites. Subjects saw an image (sketch or composite) and then attempted to select the target face in a series of photographs. The effect of image quality (goodness-of-fit of the image with the target person) was a second variable. Better images led to better recognition performance. Image type was marginally significant--sketches were better than composites. The results have implications for criminal identification systems. Language: en

Image information recording and reproducing apparatus

Abstract: PURPOSE: To make it possible to supply a reproducer directly with an image, to elongate the lifetime of a storage device, to reduce the price of the device and to obtain an excellent image quality by combining a camera unit which is equipped with a recording medium and the memory device which has its output rate varialbe. CONSTITUTION: A camera unit 10, which is equipped stationarily with a photoelectric converter 43 for generating a number of elesctronic signals in response to an optical image so that the signals can be sequentially fed to an outside circuit as image information signals, a memory device 45 for recording the signals from the converter 43, and with an electric signal feeder 49, is combined with an outside memory device 11 which is equipped with a signal receiving unit adapted to be electrically connected for receiving the image information signals from the device 45 and with a semiconductor storage element having its output rate easily variable. The output of a system 12 is fed directly to a TV receiver thereby to effect the image reproduction. COPYRIGHT: (C)1979,JPO&Japio

Evaluation of Radiographic Images by Entropy: Application to Development Process

Abstract: A method for the quality evaluation of radiographic images in terms of entropy is presented By this method, the image quality can be synthetically evaluated by a single number The method presented is used to calculate the amount of information contributed by the image of a uniform lucite step-wedge object The new method is also applied to the evaluation of development processes The calculated results show that the information quantities conveyed by tank developed and automatic processor developed images are 176 and 151 bits per image on the average (the maximum of information quantity can be equally transmitted with 232 bits per image) The performance of tank development is found to be superior to that of automatic processor development

Image quality in cranial computed tomography.

Abstract: Image quality in cranial computed tomography (CT) was evaluated with phantom and patient studies on both a first (single beam) and a second (multiple beam) generation scanner. When comparable radiation doses were used, there were only minor differences in resolution, low contrast detectability, and noise level. The pattern of noise relative to the size of the area in which it was measured was somewhat different. On patient studies, no differences were found when contrast-material-filled vessel visibility and gray--white matter distinction were analyzed. A lesion was obscured by streak artifacts in one scanner in one of 22 patients scanned on both machines. The major factor in image quality as seen in the two scanners seemed to be in the production of artifacts. This was apparent in artifacts from motion, high contrast discontinuities, beam hardening, and edge enhancement. Multiple factors must be considered in assessing CT image quality. In particular, further studies to quantitatively evaluate noise quality and artifact production are needed.

Improvement of scanner performance by subtraction of Compton scattering using multiple energy windows.

Abstract: In many radiological imaging situations photon scattering leads to degradation of image quality. Energy discrimination can substantially reduce the effects of scatter in radiosotope imaging. However, with low energy isotopes such as 99TCm the limited energy resolution of scintillators allows only imperfect discrimination against scattered photons. With only a single energy channel available in a rectilinear scanner or gamma camera, a choice must be made between (a) the use of a high base-line energy, resulting in reduced sensitivity because of rejection of unscattered photons, or (b) a low base-line settng to maximize the countrate at the expense of image contrast and resolution. Sanders et al. (1969), and Beck and Harper (1966), have examined the effects of energy selection to establish the optimum window setting for 99Tcm brain scanning. Rollo and Schulz (1971), and Sanders et al. (1972), extended this work to include an assessment of the detectability of lesions by observe-performance measurements. The...

Subjective Assessment of Interline Flicker in Television Displays—A First Approach

Abstract: Interline flicker is generally most noticeable in small high luminance areas and at high contrast transitions occurring across the television line structure. A subjective experiment was conducted to determine the impairment arising from interline flicker for simple counterphase rectangular patterns whose width and height was varied. A rapid dimunition in picture quality was found to occur as soon as the counterphase format of the pattern (corresponding to the line structure) became readily discernible. Possible methods of reducing the visibility of interline flicker are discussed.

Comparison of Image Quality and Information Capacity for Different Model Imaging Systems

Abstract: The paper presents the results of reproducing a continuous-tone picture by a set of different model imaging systems. Systems with equal information capacity may nevertheless produce continuous-tone reproductions which differ remarkably in “image quality". For this reason, information capacity cannot be accepted as a general measure of image quality when different imaging systems are to be compared.

Laser beam recorder

Abstract: PURPOSE:To obtain image quality, stability of image and high speedness equivalent to those of ordinary laser beam recorders by the combination of a galvanometric vibrating mirror and a reflecting mirror and a photoelectro transducer without requiring any high speed rotary polyhedral mirror and special devices such as F-theta lens, etc.

The Spin Scan Camera System: Geostationary Meteorological Satellite Workhorse for a Decade

Abstract: The spin scan camera was first flown on ATS-1 from 1966 to 1973 to continuously monitor the global atmospheric circulation. Later, modified versions with improved sensor capabilities were flown on ATS-3 and SMS. Today, the GOES series of spin scan cameras is in regular operational use. The value of the spin scan camera as a dependable meteorological workhorse requires proper functioning of the entire camera system, composed of four main elements: a) a spinning spacecraft whose highly stable and predictable motions generate a time divisible precision scan and therefore a metric image; b) a telescope having both on-axis image quality and a wide field of view; c) a data chain which in-corporates duty cycle improvement and uses the spacecraft as a communication link to distribute the image data to users; and d) image display and analysis techniques which permit organizing a large number of images in the time domain and efficiently selecting and measuring data of greatest importance.

Effect of spatial sampling on an acoustical image reconstruction

Abstract: It is often difficult and unpractical, in the acoustic imaging area, to insert a focusing lens between the observed object and the ultrasonic receiver. Furthermore, the focal length must, in the B scan mode, be varied very fast in order to keep the line sources lying at different depths well focused. A spatial‐sampling scheme may be used for circumventing these problems by taking off the possibly complex processing unit from the element contacting the observed object, without additional complexity or degradation in the flexibility and usefulness of the apparatus. The sampling is done using a receiving transducer array to convert the acoustic signals into electrical ones, which may be amplified before being applied to another reemitting transducer array: an acoustical field identical to the original one is so reconstructed. The sampling operation will, however, alter the image quality by introducing parasitic images. The dependence of the perturbations upon the system parameters is studied in this paper and criteria are derived for limiting them.

Twoocolor image developing process

Abstract: PURPOSE:To eliminate color blurring with a simplified process, and to improve image quality and color tone, by using developing means utilizing intense electrostatic force and aerosol in an electrophotographic developing process copying 2-color original images.

Surface plate for color pick up tube

Abstract: PURPOSE:To prevent the lowering of picture quality due to the distortion of the color filter and duplication and to enable the color pick up tube surface plate having a good yield rate using metallic film, by changing the position of the oblique metallic electrode to the stripe shape color filter.

Tactical Photointerpreter Evaluations Of Hardcopy And Softcopy Imagery

Abstract: The experiment described in this paper was designed to evaluate, in a statistically valid manner, the relative image quality of nine digital images (algorithms) and two film images (laser print and duplicate positive). Three important (and basically different) modes of presenting imagery were compared: a duplicate positive film, a laser film print of a digital image, and a CRT display of the digital images. Imagery was selected in coordination with the Army to assure the tactical relevance of the questions and imagery chosen. Five operational interpreters, having from two to five years experience, took part in the experiment as image quality evaluators. For any particular image question, there were eleven (two film and nine digital) versions of the image on which to judge relative image quality. Each interpreter examined all eleven versions in a pairwise (i.e., two-at-a-time) fashion and specified both the version preferred and the strength of the preference. The interpreter was asked to evaluate the imagery relative to a particular question. For example, a question might be in which image could the interpreter most easily see the wheels on a vehicle. In addition to target-specific questions, there were also general questions on the overall interpretability of scenes.

Forming method of image

Abstract: PURPOSE:In the device for forming a secondary electrostatic latent image, to control the forming requirement of an image in order to enhance the image quality by measuring an electric current due to an ionic current with a predetermined detecting means.

Regenerative correction system for film picture

Abstract: PURPOSE:To obtain a regenerated picture of high quality, by regenerating a reference signal recorded in a vertical flyback interval between pictures on a film simultaneously to pictures, by correcting a regenerated picture on the film on the basis of this reference signal, and by removing the deterioratin of the picture quality due to an optical element system.

Enhancement of quality for record image

Abstract: PURPOSE:To emphasize the surroundings of an image and improve the image quality with the formation of color gradation on its surroundings by synthesizing a train of pulses of the reflecting light of a document via differential calculation circuit and averaging circuit in order to form a light beam for making an image by modulating the light from the light source with the pulse signal.