YE0178 BlankFilm White Balacing Test Target 4:3 Ratio 100% WHITE
TEST CHART Shading Measurement Chart
The test chart consists of a blank film between two glass panes.
The (reprographic) film is of the same material as the other ESSER
TEST CHARTS transparencies (D280, D240, D205).
The test chart is designed for shading measurement under the same
lightning conditions as other transparency measurements.
It is possible to perform shading measurements on illuminator (LG2,
LE6) without any chart. But then lightning conditions are different
to other measurements with test transparencies. By using a test
transparency the light intensity of an illuminator changes. This is
caused by two superimposed factors
a) the filter effect of the film and glass (25% light absorption)
and
b) the light remission of the transparency ack in the illuminator
While factor a) is predominant with the LG2, the remission factor
b) is predominant with the lightning sphere LE6, i.e. the light
intensity rises significantly when a test chart is inserted. To
carry out shading measurement under the same lighting condition as
other measurements the use of the YE0178 is essential.
Definition of white shading or white level uniformity
Determination of maximum white level variations in various areas of
the picture, when the camera is directed at an evenly illuminated
test chart.
Measuring equipment
Oscilloscope; video amplitude meter
Measuring conditions
Gamma correction: ON
Iris aperture: F/4 2/3” CCD
Gain: 0dB
White balanced
The illumination of the test chart has to be adjusted so that the
R, G, B output signals are equal to 700mV/75ohms (nominal
amplitude). Lens initially focussed on the test chart (or an other
suitable test chart
e.g. YE0120) and then de-focussed.
Shading correctors: ON
Zoom: Positioned to minimize the effect of vignetting and shading
of the test chart.
Measuring procedures
Measurements are made on the R, G, B signals at the camera output
and then repeated for two picture zones defined as follows:
a) within a rectangular zone, the height and width of the picture
(zone A)
b) outside this rectangle (zone B)
On the basis of these measurements, the differences of level for
R-G, R-B and B-G are calculated and the maximum peak-to-peak
variantions recorded for each zone.
Presenting the results
The results, expressed in % of the nominal signal, are recorded in
a table:
Suzie Xia
International Sales Dept.
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Shenzhen ThreeNH Technology Co., Ltd
Add: 4/F, Building 8, Nangang Second Industry Zone, Xili, Nanshan
District, Shenzhen, 518055 China.
Tel: 0086-755-27198826 Ext: 601
Fax: 0086-755-27190609
Mobile: 0086-13510878132
Email: y@3nh.com
Skype: y@3nh.com
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Website: www.3nh.com/en
