Faulty Pixels In Images - Nokia RM-42 Service Manual

RM-42
Nokia Customer Care Camera Module Troubleshooting
Figure 93 Bit errors caused by JPEG compression
One type of bit error is a lack of bit depth. In this case, the image is almost totally black under normal conditions,
and only senses something in very highly illuminated environments. Typically this is a contact problem between
the camera module and the phone main PWB. You should check the camera assembly and connector contacts.
If the fault is in the camera module, bit errors are typically visible only when using some specific image
resolution. For example, in case of a viewfinder fault, the error might exist but is not visible in a full size image.

Faulty pixels in images

Faulty pixels are pixels that do not respond to light in the same way as the pixels around them. There are three
main types of faulty pixels, dead, stuck and hot pixels.
Dead pixels are always black or significantly darker than their surrounding. Dead pixels appear as black spots
in all lightning conditions. Camera modules producing images with dead pixels that are clearly noticeable should
be replaced.
If the pixel remains always saturated to its maximum value it is stuck. Stuck pixels may appear as red, green,
blue or white spots in all lightning conditions. Camera modules producing images with one or more stuck pixels
should be replaced.
Hot pixels are pixels that easily saturate in dim light conditions. It is normal to get a lot of noise and hot pixels
in night conditions or otherwise dark conditions. The hot pixels should disappear when the ambient light is
increased, but may still appear in darker areas of an otherwise well illuminated scene.
When examining an image for defect pixels test images should be viewed as 100% enlargements on a PC
monitor.
Page 8–16 Company Confidential 9241872 (Issue 1)
Copyright ©2005 Nokia. All Rights Reserved.