Camera sensors - hot / dead pixels - pixel remapping

[MFloyd]

I have a question for Nikon owners: hot / faulty pixels are generally eliminated by "pixel remapping" i.e.by wiring the faulty pixel to the surrounding pixels, and by this way averaging out the error. Apparently it would be possible to initiate this pixel remapping through a hidden, undocumented function: this would comprise pushing the function "sensor cleaning" twice with a given interval, as well as precise exposure and ISO settings. Can somebody highlight me, and confirm the aforementioned ? Thanks 

[Bjørn Rørslett]

The Nikon repair facility does this by running the camera through a test procedure in which each pixel above a certain threshold is put on a "remapping" list later dealt with by camera firmware. There is no physical rewiring. If a pixel is "stuck" it sometimes can become unstuck by repeated sensor remapping, a feature provided by some camera models.

Watching the output from such tests can be a little unsettling, I'll admit that after observing the process a few times. However, the relief is in the sheer numbers of functional vs bad pixels.

[MFloyd]

Thank you Bjørn, for the timely answer 👍🏻  If my understanding is correct, you seem to confirm that a procedure exists to do this at home. Have you an idea in (1) what consists the precise procedure; and (2) to which camera bodies this applies ? Thanks 😊

[Bjørn Rørslett]

My AW1 has it. Probably lots more models, but I prefer letting the repair facility do the remapping in connection with the yearly maintenance service so really haven't looked after the feature.

The procedure used by Nikon techs involves a special rig, measuring instruments,  and bespoke computer software. Not something for home use.

[MFloyd]

👌🏻

[Frode]

My AW1 has it. Probably lots more models, but I prefer letting the repair facility do the remapping in connection with the yearly maintenance service so really haven't looked after the feature.

The procedure used by Nikon techs involves a special rig, measuring instruments,  and bespoke computer software. Not something for home use.

Bjørn, may I ask where you deliver your gear for the yearly maintenance service? Also, are you specific in what kind of service you want?

Might be a good idea to have such a yearly service....🙂

[Bjørn Rørslett]

FotoCare (Oslo) and my friend Vegard Kvamme (head tech) are the main ingredients. Usually the maintenance for cameras is cleaning, checking focus and mount alignment, and sundry other minor issues (for example, replacing covers, remapping dead or hot pixels). Lenses (other than those Erik fixes for me) can get a relubrication once in a while. Over the years, I have had AF motors or VR units replaced as well, but that is not very common. Only had to do this with 200/2 AFS and 300/2.8 AFS if memory serves.

[Bernard Delley]

I tried to fill in that missing information at this dpreview thread:    https://www.dpreview.com/forums/post/51996082

it appears that recent camera models do the remapping when you activate the "clean sensor now" once.

several years ago I wrote a set  of Linux programs to analyze RAW files  for such and other properties. Here is the cryptic output for a D500 black frame NEF with hot pixels:

160927_1742_DSC_3947_5.NEF
Camera Model Name               : NIKON D500
ISO                             : 1600
Exposure Time                   : 1/5
Black Level                     : 400 400 400 400
iblack=  400  ierr    0     >>rggb<<
ck_wh  5599  3728 65535 17000 
ck_thr          211         189         178         196         211           
hot pixel record thr=   211
  2433   213     0   # b4    320
  3255  1177     0   # b4   3594
  1418  1304     0   # r1  13161
  4412  1669     0   # g3    488
  5348  2283     0   # g3    219
  3303  2534     0   # g2   6030
  1220  2553     0   # g3    393
  3496  3138     0   # r1    509
  3485  3320     0   # g2    365
  5539  3369     0   # b4    245
  5539  3370     0   # g2  15983
  2231  3621     0   # b4   4434
number of hot pix       12