WO1991002432A1 - Appareil d'evaluation de la qualite de cameras de television - Google Patents

Appareil d'evaluation de la qualite de cameras de television Download PDF

Info

Publication number
WO1991002432A1
WO1991002432A1 PCT/GB1990/001191 GB9001191W WO9102432A1 WO 1991002432 A1 WO1991002432 A1 WO 1991002432A1 GB 9001191 W GB9001191 W GB 9001191W WO 9102432 A1 WO9102432 A1 WO 9102432A1
Authority
WO
WIPO (PCT)
Prior art keywords
chart
markings
light
cylindrical
diffuser
Prior art date
Application number
PCT/GB1990/001191
Other languages
English (en)
Inventor
Alan Keith Sefton
Original Assignee
Pearpoint Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Pearpoint Limited filed Critical Pearpoint Limited
Publication of WO1991002432A1 publication Critical patent/WO1991002432A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N17/00—Diagnosis, testing or measuring for television systems or their details
    • H04N17/002—Diagnosis, testing or measuring for television systems or their details for television cameras

Definitions

  • This invention relates to assessment or testing apparatus for T.V. inspection cameras.
  • test charts carry markings which enable several parameters of a T.V. camera to be assessed, and simple forms of test chart appear regularly on domestic T.V. receivers.
  • the charts are printed on flat cards or may be in the form of flat transparencies, and are usually positioned suffic- intly far from the camera to avoid significant differ ⁇ ential focus effects between the centre and periphery of the card. This is usually perfectly satisfactory, as most T.V. lenses are designed for flat-field operation.
  • T.V. inspection cameras are often preferred to have lenses with significant field curvatures and, for conduit inspection, the ideal 'constant focus 1 surface may be cylindrical.
  • Advanced-technology cameras can view conduit walls by moving the field of view off the central axis of the conduit, and this can be achieved by pivoting the lens or sensor or, better, by shifting the sensor as described in our British Patent Application No. 2210530A or No. 215941A.
  • an apparatus for use in assessing T.V. inspection cameras comprising, essentially, a generally-cylindrical chart presenting test markings on its inner face.
  • the said test chart is mounted within a casing having an end opening for the camera to be assessed, and having lamps arranged around the cylindrical chart for controlled illumination of the markings.
  • the chart may comprise a transparency carried in a light- diffuser.
  • Figure 1 is a perspective view, partly broken away, showing an apparatus according to the invention for use in assessing T.V. inspection cameras;
  • Figure 2 is a composite illustration of a test chart for .use in the apparatus of Fig. 1, and including 'developed' sections of the chart markings; and,
  • Figures 3A to 3G are reproductions of images dis ⁇ played during tests.
  • the apparatus com ⁇ prises a closed metal casing 10 in which a cylindrical test-chart transparency 11 is positioned.
  • the trans ⁇ parency is carried in an inner cylindrical diffuser 12 which is surrounded by an outer cylindrical diffuser 13.
  • the diffusers are mounted in- the principal compart ⁇ ment 14 of the casing, which has white inner walls to reflect diffused light.
  • Each lamp pair has an ends/side shield 16, and the chart is illuminated by light reflected from the white inner walls of the compartment and diffused by the two diffusers 12 and 13.
  • a T.V. inspection camera 17 to be tested is mounted in a power supply compartment 18 of the casing, so that the camera lens (not shown) is ⁇ directed into the cylin ⁇ drical chart.
  • the camera has a connector socket 19.
  • the camera In use of the apparatus, with a test chart transparency installed, the camera is inserted into the compartment 18 and the chart is illuminated by the lamps 15.
  • the markings on the chart 11, in the present embodiment, include Depth of Field 20, Luminance Resolution 21, Chrominance Resolution 22, Angle of View 23 including Top Angle of View 23A, Side Angle of View 23B, Side View Resolution 23C, and Side Angle of View 23D, Colour - Bars 24 and Grey Scale 25, and by imaging the viewed chart on an inspection screen such as a VDU monitor the follow ⁇ ing parameters of the camera can be tested:
  • Luminance resolution can be measured
  • Chrominance resolution forwards and sideways
  • Angle of radial view head articulation can be measured
  • Phase errors can be detected
  • Angle of view can be measured.
  • Iris control can be checked by varying strength of illumination; the on/off switching of selected lamps allows the colour temperature to be maintained at 3000k. Also, the minimum depth of field can be measured.
  • the focus range can be checked; by ensuring that the iris is fully open before the test commences, the minimum focus position can be measured
  • the contents, as opposed to the presentation, of the markings are more or less conventional and, for simplicity, the several bands or strips of 22, and also 24 and 25, are uniformly shaded. In practice, however, those bands are of different densities. Also, in Figures 3A to 3G the images are shown as clear images whereas, in reality, the areas around the centre may be slightly shadowed.

Landscapes

  • Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Biomedical Technology (AREA)
  • General Health & Medical Sciences (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Testing, Inspecting, Measuring Of Stereoscopic Televisions And Televisions (AREA)

Abstract

L'appareil destiné à être utilisé pour évaluer la qualité de caméras TV d'inspection (17) comprend un diagramme cylindrique (11) présentant des marques de test (20 à 25) sur sa face intérieure. Le diagramme de test est monté à l'intérieur d'une structure (10) comportant un orifice terminal (19) destiné à la caméra (17) dont la qualité est à évaluer, et comportant des lampes (15) agencées autour du diagramme cylindrique (11) assurant l'éclairage commandé des marques, lesquelles sont affichées sur un moniteur à écran de visualisation afin de procéder à l'évaluation de la qualité. Ledit diagramme (11) dans une de ses formes comprend un élément transparent porté dans un diffuseur de lumière (12, 13).
PCT/GB1990/001191 1989-08-01 1990-07-31 Appareil d'evaluation de la qualite de cameras de television WO1991002432A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8917552.5 1989-08-01
GB898917552A GB8917552D0 (en) 1989-08-01 1989-08-01 Apparatus for assessing t.v.cameras

Publications (1)

Publication Number Publication Date
WO1991002432A1 true WO1991002432A1 (fr) 1991-02-21

Family

ID=10660968

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1990/001191 WO1991002432A1 (fr) 1989-08-01 1990-07-31 Appareil d'evaluation de la qualite de cameras de television

Country Status (3)

Country Link
AU (1) AU6045690A (fr)
GB (1) GB8917552D0 (fr)
WO (1) WO1991002432A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0819927A2 (fr) * 1996-06-21 1998-01-21 dSam Limited Appareil de test optique pour un système optique

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Internationale Elektronische Rundschau, Volume 19, No. 9, September 1965, W. HOPMANN: "Prufprojektor fur Fernsehkamera", page 493 see the whole article *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0819927A2 (fr) * 1996-06-21 1998-01-21 dSam Limited Appareil de test optique pour un système optique
EP0819927A3 (fr) * 1996-06-21 1998-12-23 dSam Limited Appareil de test optique pour un système optique

Also Published As

Publication number Publication date
AU6045690A (en) 1991-03-11
GB8917552D0 (en) 1989-09-13

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