Nokia NHL-2NA Series, Инструкции по устранению неисправностей

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CCS Technical Documentation
NHL-2NA
Issue 1 06/02 ¤ Nokia Corporation Page 11
ratory environment. Thus subjective analysis should be used.
If no visible defects (items 1-4) can be found, a couple of test images should be taken
and checked. Generally, a well illuminated typical indoor office scene, such as the one in
A good picture taken indoors, can be used as a target. The main considerations are:
• The back window has to be clean
• Amount of light: 300 – 600 lux (bright office lighting) is sufficient
• The scene should contain e.g. small objects for checking sharpness and distance
to them should be in order of 1 – 2 meters
• If possible, compare the image to another image of the same scene, taken by dif-
ferent device
The taken images should be analyzed on PC screen at 100% scaling simultaneously with
reference image. Pay attention to the computer display settings; at least 65000 colors
(16 bit) have to be used. 256 (8-bit) color setting is not sufficient, and true color (24 bit,
16 million colors) or 32 bit (full color) setting is recommended.
If there appears to be a clearly noticeable difference between the reference image and
the test images, the module might have misfocused lens. In this case, the module should
be changed. Always re-check the resolution after changing the camera. If a different
module produces the same result, the fault is probably in camera window. Check the
window by seeing through it when replacing the module.
Effects of dirty or defective back window
The following series of images demonstrates the effects of fingerprints on the camera
back window.
It should be noted that the effects of any dirt in images can vary very much; it may be
difficult to judge if the window has been dirty when some image has been taken or that
has something else been wrong. That is why the cleanness of the back window should
always be checked and the window should be wiped clean with a suitable cloth.