If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
#1
|
|||
|
|||
Olympus C5050 pixel remapping failure
My Olympus C5050 seems to have developed a hot pixel - a white spot that shows up fairly clearly. Unfortunately, when I try the pixel remapping function of the camera, the spot remains. It appears that this spot is a square of four pixels, appearing all white. This is surrounded by a 1 pixel wide border that is darker than the area around it. So, I have a 4 x 4 pixel bad spot, though I wonder if the dark area may be a result of the bright 2 x 2 area in the center. Looking back at old pictures, it apparently appeared while the camera was still under warranty, had I discovered it then. Unless someone can tell me of tricks to get the remapping to work better, I guess it is off to pay Olympus a huge amount of money. Sigh. (No, I am not ready to replace it. When I spent that much money, I expect it to last a bit longer than this.) Alan |
#2
|
|||
|
|||
"Alan" wrote
My Olympus C5050 seems to have developed a hot pixel - a white spot that shows up fairly clearly. Unfortunately, when I try the pixel remapping function of the camera, the spot remains. It appears that this spot is a square of four pixels, appearing all white. This is surrounded by a 1 pixel wide border that is darker than the area around it. So, I have a 4 x 4 pixel bad spot, though I wonder if the dark area may be a result of the bright 2 x 2 area in the center. It's not 4 bad pixels, it's only 1 bad pixel. The way the Bayer sensor works is to interpolate color values from neighboring pixels. 1 hot pixel will always show up as at least 4 hot pixels by the time the image is convtered to a RGB format. Regardless, the whole point of pixel mapping is to get rid of those problems. I'm surprised it doesn't work. I'd give Olympus hell for selling you a broken feature. |
#4
|
|||
|
|||
"Alfred Molon" wrote
Obviously it's not only one pixel, otherwise pixel mapping would take care of it, wouldn't you agree ? Pixel mapping maps out bad pixels by using the neighbouring pixels. But the symptoms he describes are exactly what one would expect to see from a single hot sensor. That creates a block of 4 hot pixels, bue to Bayer processing of the image. Add some jpeg artifacts to it, and you've got a ring around that block. It sounds more like pixel mapping isn't working on his camera, or at least isn't working on that specific hot pixel. It's more likely that behind those four damaged pixels there is a huge block of broken pixels, so huge that even pixel mapping is overwhelmed. Possibly, although that's not what he describes. In any case this doesn't help the original poster. The only thing he might try is to leave the camera without batteries for 24 hours, so that it fully resets to the factory default. Then try again the pixel mapping and if that still doesn't help send it to Olympus. Could work. Maybe the buffer that holds the hot pixel information is full. I'm not sure if a reset would clear that, or not. |
#5
|
|||
|
|||
"Alfred Molon" wrote
Obviously it's not only one pixel, otherwise pixel mapping would take care of it, wouldn't you agree ? Pixel mapping maps out bad pixels by using the neighbouring pixels. But the symptoms he describes are exactly what one would expect to see from a single hot sensor. That creates a block of 4 hot pixels, bue to Bayer processing of the image. Add some jpeg artifacts to it, and you've got a ring around that block. It sounds more like pixel mapping isn't working on his camera, or at least isn't working on that specific hot pixel. It's more likely that behind those four damaged pixels there is a huge block of broken pixels, so huge that even pixel mapping is overwhelmed. Possibly, although that's not what he describes. In any case this doesn't help the original poster. The only thing he might try is to leave the camera without batteries for 24 hours, so that it fully resets to the factory default. Then try again the pixel mapping and if that still doesn't help send it to Olympus. Could work. Maybe the buffer that holds the hot pixel information is full. I'm not sure if a reset would clear that, or not. |
#6
|
|||
|
|||
In article ,
says... "Alfred Molon" wrote Obviously it's not only one pixel, otherwise pixel mapping would take care of it, wouldn't you agree ? Pixel mapping maps out bad pixels by using the neighbouring pixels. But the symptoms he describes are exactly what one would expect to see from a single hot sensor. That creates a block of 4 hot pixels, bue to Bayer processing of the image. Add some jpeg artifacts to it, and you've got a ring around that block. Actually Bayer colour interpolation is a bit more complex than that. It uses more than just four adiacent pixels. See for instance this R1 G1 R2 G2 R3 G3 G1 B1 G2 B2 G3 B3 R4 G4 R5 G5 R6 G6 G4 B4 G5 B5 G6 B6 R7 G7 R8 G8 R9 G9 G7 B7 G8 B8 G9 B9 To calculate the RGB values of the pixel at R5 you need to use the R values at R2, R6, R8 and R4 - and it also wouldn't hurt to use the remaining R values (R1, R3, R7 and R9). In addition, without knowing how exactly the colour interpolation algorithm is implemented, I suspect that also the neighbouring G and B values are used to calculate the RGB value of the pixel at R5. In any case there are more than just four pixels involved. -- Alfred Molon ------------------------------ http://groups.yahoo.com/group/Olympus_405080/ Olympus 5060 resource - http://myolympus.org/5060/ Olympus 8080 resource - http://myolympus.org/8080/ |
#7
|
|||
|
|||
In article ,
says... "Alfred Molon" wrote Obviously it's not only one pixel, otherwise pixel mapping would take care of it, wouldn't you agree ? Pixel mapping maps out bad pixels by using the neighbouring pixels. But the symptoms he describes are exactly what one would expect to see from a single hot sensor. That creates a block of 4 hot pixels, bue to Bayer processing of the image. Add some jpeg artifacts to it, and you've got a ring around that block. Actually Bayer colour interpolation is a bit more complex than that. It uses more than just four adiacent pixels. See for instance this R1 G1 R2 G2 R3 G3 G1 B1 G2 B2 G3 B3 R4 G4 R5 G5 R6 G6 G4 B4 G5 B5 G6 B6 R7 G7 R8 G8 R9 G9 G7 B7 G8 B8 G9 B9 To calculate the RGB values of the pixel at R5 you need to use the R values at R2, R6, R8 and R4 - and it also wouldn't hurt to use the remaining R values (R1, R3, R7 and R9). In addition, without knowing how exactly the colour interpolation algorithm is implemented, I suspect that also the neighbouring G and B values are used to calculate the RGB value of the pixel at R5. In any case there are more than just four pixels involved. -- Alfred Molon ------------------------------ http://groups.yahoo.com/group/Olympus_405080/ Olympus 5060 resource - http://myolympus.org/5060/ Olympus 8080 resource - http://myolympus.org/8080/ |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
C8080 by Olympus Pixel Mapping? White Spots ? Any one have this problem? | marv | Digital Photography | 0 | September 18th 04 10:12 PM |
How to open olympus c5050 | blub | Digital Photography | 1 | July 14th 04 04:09 PM |
Little review of the Olympus RC | Mike Henley | 35mm Photo Equipment | 5 | July 2nd 04 04:42 AM |