Johnson's criteria, or the Johnson criteria, created by John Johnson, describe both spatial domain and

frequency domain In physics, electronics, control systems engineering, and statistics, the frequency domain refers to the analysis of mathematical functions or signals with respect to frequency, rather than time. Put simply, a time-domain graph shows how a s ...

approaches to analyze the ability of observers to perform visual tasks using image intensifier technology. It was an important breakthrough in evaluating the performance of visual devices and guided the development of future systems. Using Johnson's criteria, many predictive models for sensor technology have been developed that predict the performance of sensor systems under different environmental and

operational An operational definition specifies concrete, replicable procedures designed to represent a construct. In the words of American psychologist S.S. Stevens (1935), "An operation is the performance which we execute in order to make known a concept." F ...

conditions.

History

Night vision systems enabled the measurement of visual thresholds following

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposing ...

. The 1950s also marked a time of notable development in the performance modeling of night vision imaging systems. From 1957 to 1958, Johnson, a United States Army Night Vision & Electronic Sensors Directorate (NVESD) scientist, was working to develop methods of predicting target detection, orientation, recognition, and identification. Working with volunteer observers, Johnson used image intensifier equipment to measure the volunteer observer's ability to identify scale model targets under various conditions. His experiments produced the first empirical data on perceptual thresholds that was expressed in terms of line pairs. In the first Night Vision Image Intensifier Symposium in October 1958, Johnson presented his findings in a paper entitled "Analysis of Image Forming Systems", which contained the list that would later be known as Johnson's criteria.

Criteria

The minimum required resolution according to Johnson's criteria are expressed in terms of line pairs of

image resolution Image resolution is the detail an image holds. The term applies to digital images, film images, and other types of images. "Higher resolution" means more image detail. Image resolution can be measured in various ways. Resolution quantifies how ...

across a target, in terms of several tasks: * Detection, an object is present (1.0 +/− 0.25 line pairs) * Orientation, symmetrical, asymmetric, horizontal, or vertical (1.4 +/− 0.35 line pairs) * Recognition, the type object can be discerned, a person versus a car (4 +/− 0.8 line pairs) * Identification, a specific object can be discerned, a woman versus a man, the specific car (6.4 +/− 1.5 line pairs) These amounts of resolution give a 50 percent

probability Probability is the branch of mathematics concerning numerical descriptions of how likely an event is to occur, or how likely it is that a proposition is true. The probability of an event is a number between 0 and 1, where, roughly speakin ...

of an observer discriminating an object to the specified level. Additionally, the line pairs refer to lines being displayed on an

interlaced Interlaced video (also known as interlaced scan) is a technique for doubling the perceived frame rate of a video display without consuming extra bandwidth. The interlaced signal contains two fields of a video frame captured consecutively. This ...

CRT monitor. Each line pair corresponds to 2 pixels of a film image, or an image displayed on an LCD monitor.

History

Criteria

References

Further reading

Papers

Books