Image Quality Analysis; Testing For Dust In Camera Module - Nokia RM-392 Service Manual

RM-392; RM-393
Camera Module Troubleshooting
In Service software press "Read", and the Camera Configuration window shows available DCC data file name
and its version to upload. If the previous camera configuration was the same as installed, then Current
Configuration Version displays DCC data version currently in the terminal memory, otherwise it shows xxx.xxx.
Press "Upload" and then the DCC data settings are updated.
Figure 101 DCC data update

Image quality analysis

Testing for dust in camera module

Symptoms and diagnosis
For detecting these kinds of problems, take an image of a uniform white surface and analyse it in full
resolution. A good quality PC monitor is preferred for analysis. Search carefully, since finding these defects
is not always easy. Figure "Effects of dust on optical path" is an example image containing easily detectable
dust problems.
When taking a white image, use uniformly lightened white paper or white wall. One possibility is to use
uniform light but in this case make sure that the camera image is not flickering when taking the test image.
In case flickering happens, try to reduce illumination level. Use JPEG image format for analysing, and set the
image quality parameter to 'High Quality'.
Black spots in an image are caused by dirt particles trapped inside the optical system. Clearly visible and
sharp edged black dots in an image are typically dust particles on the image sensor. These spots are searched
for in the manufacturing phase, but it is possible that the camera body cavity contains a particle, which may
move onto the image sensor active surface, for example, when the phone is dropped. Thus it is also possible
that the problem will disappear before the phone is brought to service. The camera should be replaced if the
problem is present when the service technician analyses the phone.
If a dust particle is lying on the infrared filter surface on either side, they are hard to locate because they are
out of focus, and appear in the image as large, grayish and fading-edge 'blobs'. Sometimes they are invisible
to the eye, and thus the user probably does not notice them at all. However, it is possible that a larger particle
disturbs the user, causing need for service.
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