Olympus discusses 'Auto Pixel Mapping'!
By
Mike Tomkins
(Friday, August 17, 2001 - 18:38 EDT)
Firmware update will be offered to American E-10 owners to add functionality already present in the C-4040Z...
A common complaint amongst digital camera owners of all brands, particularly as their cameras get older, is that of pixels that are always on or off ('stuck' or 'dead'). The general trend is that, as camera resolutions get higher, the problem becomes more likely to manifest itself. Simply put, this is because you have more pixels at a higher density; more pixels means more chance of seeing one fail. Note that the 'hot' pixels you see on long exposures are unrelated - these are a factor of exposure time and temperature, and perform normally on most exposures. These 'dark current noise' pixels occur on basically all digital cameras to some degree, and are often reported as stuck pixels when they're not...
Owners of Olympus' Camedia E-10, the first 4 megapixel digital camera to be announced, have discussed this much on the net recently. A casual browsing of digital camera-related newsgroups and forums around the Internet might seem to suggest the camera suffers more than others from dead or stuck pixels, but this is probably not a fair assumption. The disparity could well in part be due to the fact that people only tend to speak out when they have problems. Certainly, the E10 is higher resolution than most cameras in the marketplace, and has been around for far longer than the 4 and 5 megapixel digicams that are now beginning to appear in numbers. That head start and higher number of pixels than most other cameras has probably had the effect of making the camera seem more problematic than it is.
Either way, we first heard a few days ago that Olympus Europe was releasing new firmware that promised to correct these problems for the E-10, by 'mapping out' problematic pixels so that they wouldn't affect the final picture. Pixel mapping is a process which is usually done with all new digital cameras at the factory, so they are essentially 'perfect' out of the box - even though the realities of life mean that the image sensors the cameras contain often do suffer a few problematic pixels from day one. Olympus' Camedia C-4040Zoom already includes an 'Automatic Pixel Mapping' algorithm in the firmware out-of-the-box, and it seems that this capability has been added to the latest firmware for the Camedia E-10 as well.
We spoke with Olympus America Inc. on the subject, and they've provided us with an excellent and informative document on the matter, describing the problems (and red herrings) in detail, and explaining how the new firmware corrects them. The company also told us that the firmware update for the E-10 will be available to US customers, regardless of whether they've seen problems yet or not. The company will remap dead or stuck pixels in its digital cameras free of charge as a warranty service, something not all manufacturers are willing to do... Olympus will also update the Camedia E-10's firmware for customers who've yet to see a problem, charging only a shipping and handling fee of $19.95.
Olympus' statement on pixel failure and Automatic Pixel Mapping is as follows:
Olympus C-4040 Zoom, APM and an E-10 Upgrade.
With today's higher end cameras, 3 megapixel and higher, there is some discussion about pixel issues. These include dead pixels, stuck pixels and hot pixels as well as noise. For most users this is not a problem and the condition will go unnoticed in their prints or on screen viewing. Digital cameras from all manufacturers can develop these CCD/CMOS errors over time, but very few will exhibit dead or stuck pixels when new. Also all CCD and CMOS sensors suffer from these conditions from the lowest to the highest pixel counts. To counter this Olympus puts all their digital cameras through several quality checks and maps the sensors before shipping and then re-checks for quality including pixel issues before shipping to their dealers. As a result we have a very low occurrence of the dead, or stuck pixel phenomena, well below 0.1%.
What are "Stuck Pixels", "Dead Pixels", "Hot Pixels" and "Noise"? How do you deal with these issues, and what additional solutions does Olympus offer?
- Dead Pixels: a pixel that reads zero or is always off on all exposures. This state produces a black pixel in the final image.
- Stuck Pixels: a pixel that always reads high or is always on to maximum on all exposures. This produces a white pixel in the final image.
- Hot Pixel: a pixel that reads high on longer exposures, and can produce white, red (orange) or green (yellow green) pixels in longer exposures. The longer the exposure the more visible the hot pixels.
- Noise: the state with fixed pattern and random patterns created as the CCD heats up, in extended use or longer exposures. If you have a long enough exposure you can find hot pixels and noise in any digital photo. Along with heat, higher equivalent ISO's result in increased noise in the digital photographs.
A common misrepresentation of dead and stuck pixels is to set the camera to a low ISO (such as ISO 100), and put the lens cap on the camera or cover the lens, resulting in a long exposure. When you look at the image you will see misrepresented pixels, some red or greenish in color, some white. This is a normal state and should not be confused with dead or stuck pixels. It is noise, and the red or greenish coloration is called Christmas tree artifacting in slang terms. The color is caused by the RGB and CMY colored filters of the CCD.
"Noise Reduction" technology found in the C-4040 Zoom will reduce this effect. A truly dead pixel is dead at all times and would not show up in this scenario, since it is black. To test for a dead pixel or stuck pixel, simply shoot a white and black card in normal light. If the pixel is dead it will show as black against the white, and if it is stuck it will show as white against the black.
To fix dead or stuck pixels the standard procedure is to send the camera in and have the CCD re-mapped by the factory service center. Some manufacturers will do this during the warranty time as a warranty service, others are charging for the service. Olympus America has chosen to re-map the CCDs with dead or stuck pixels as warranty service1. Over time all CCDs will produce stuck and dead pixels, meaning increased down time or retouching of the photographs. This is true of all CCD/CMOS cameras. To combat this the C-4040 Zoom includes a new algorithm to counter this phenomena, "Automatic Pixel Mapping" (APM). APM was developed to keep the camera operational over an extended period of time reducing the need to send the camera in for service by Olympus. APM is simple to use - all you have to do is go to the camera menu when the C-4040 Zoom is first turned on, and set the menu to pixel mapping, then go to start, and hit the OK button. The CCD re-mapping begins, taking about 10 seconds to complete. The APM only needs to be done about once a year. This functionality should bring years of easy extra use from the C-4040 Zoom. This feature cannot be added to previous C series cameras.
For the E-10, APM can be added as an upgrade when the camera is sent into the Olympus Service Center. The upgrade requires a physical re-mapping of the CCD and new firmware to be installed. After this upgrade, when the batteries are removed and replaced with new batteries the E-10 will automatically start the APM and re-map the CCD. This function takes 20 seconds or longer on the E-10. The E-10 will re-map the CCD each time the batteries are changed, when the pixel-mapping feature is turned on. For best results and longest life the B30-LBS grip system is recommended.
If a customer wants to have this function added and the camera has no problems (which will be the case with most E-10s), Olympus will do the re-mapping, checking the camera and add the new firmware for pixel mapping, charging only shipping and handling for this service. ($19.95 US2) Olympus will offer this additional function by the factory service center, but the E-10 must be sent in for this service. The addition of the APM function can only be done on [FCC labeled] Olympus America distributed E-10’s. Olympus does not repair or service gray market cameras.
1 Olympus Warranty is Limited to the area of intended distribution, which is for North and South America, and FCC approved units, and is one year in length form Olympus America Inc.
2 Shipping cost only, if additional repairs are required or requested the charge may vary, an estimate will be sent before any additional service is performed. |
Source:
Olympus America Inc.
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