Measuring and testing – Inspecting
Patent
1993-03-24
1995-03-28
Noland, Tom
Measuring and testing
Inspecting
283 70, 356243, 382 1, G01N 2184, G01N 2188
Patent
active
054006678
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a means for subjective, graphical measurement of picture sharpness/picture quality of photographical, optical, electro-optical and electronical display media, such as computer screens, photographic prints and other types of pictures, print-outs etc. The invention provides a set of test gauges for obtaining measurement of the picture quality in a simple and reliable way. Using the test gauges the measurement can be performed for instance in an office environment and by a person who neither has knowledge about or access to conventional electro-optical measuring equipment.
STATE OF THE ART
Measuring and assessing picture quality has so far been a time-consuming chore for laboratory engineers having access to expensive and complicated electro-optical measuring equipments. There are measuring rods for measuring and judging colour saturation, chrominance and density. There are also research results relating to the objective measure and subjective judgement scale of picture quality and the connection between these. Despite this nobody has so far been able to use the theories of picture quality research to meet the users' desires to measure and judge their picture material, such as computer screens, photographs and other types of pictures and print-outs with respect to picture sharpness and picture quality in a simple and reliable way.
According to the invention the problem is solved by providing a set of test gauges enabling direct reading of physical measurement results as well as the corresponding subjective expressions.
SUMMARY OF THE INVENTION
Thus, the present invention provides a means for measuring picture quality of display media. According to the invention a set of test gauges is provided containing pictures/text with varying and physically well-defined picture qualities to read directly the physical measurement results as well as corresponding subjective expressions of a picture or text with respect to picture quality. The invention is defined in the accompanying claims.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described hereafter with reference to the accompanying drawings, in which
FIG. 1 is a diagram of the relationship between subjective and objective picture quality Of photographic prints,
FIG. 2 is the corresponding diagram of computer screen images,
FIG. 3 is a diagram derived from FIGS. 1 and 2 of the relationship between photoprints and screen images, and
FIG. 4 shows an example of a selection of test gauges.
DETAILED DESCRIPTION OF THE INVENTION
The present invention enbables measurement and assessment of picture quality of for instance screen images, television sets, photographic prints, telecopier print-outs and newspaper pictures etc. using a set of test gauges, for example in the form of measuring rods, in a simple and reliable way. Using the test gauges the measurement can be performed for example in an office environment and by a person who neither has knowledge about or access to conventional electro-optical measuring equipment.
The test gauges, precision-made in laboratory environment, consist of a series of images of one and the same subject, for example a picture or a text, with varying picture quality. Each test gauge in the series is characterized firstly of an objective picture quality measure, for instance MTFA (Modulation Transfer Function Area), and secondly a subjective measure expressed as quality judgements such as "excellent", "good", "acceptable", "poor" or "very poor". Using the series of such test gauges an unknown object, for instance a computer screen image, can be graduated with respect to objective as well as subjective picture quality.
In the present description MTFA has been chosen as an example of an objective picture quality measure (see for instance "American National Standard for Human Factors Engineering of Visual Display Terminal Workstations", ANSI/HFS Standard No. 100-1988, Santa Monica, Calif.: Human Factors Society, 1988). It is defined as the area between the CSF (Contras
REFERENCES:
patent: 3505861 (1970-04-01), Schoeffer et al.
patent: 4447154 (1984-05-01), Fukui
patent: 4730213 (1988-03-01), Kelly, 3rd et al.
Feng Yingduo
stberg Olov
Noland Tom
Televerket
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