Hot pixel correction works really well

[Didier]

I was quite afraid when I noticed several fat hot pixels on my first R-D1 pictures, some of them could even be seen on ISO 200 daylight shots. I run the hot pixel function a few times and there are absolutely NO hotpixel left, even after a hundred of thest shots with ISO 1600 in the dark. I must agree this little feature alone is worth the firmware upgrade.

Didier

 

[Bob Parsons]

That's been my experience as well. I had a cluster of bright red pixels at ISO 200 in daylight that was particularly noticeable on green grass etc. I almost returned the camera but waited for the fimware upgrade. The firmware completely mapped them out 🙂


Bob.

 

[Stephan]

What does it actually do ? It sounds like the dead pixels on the sensor are replaced with an interpolated pixel, or does the camera actually do something to unblock the dead pixels ?

 

[Bob Parsons]

AFAIK it uses a form of interpolation. If you know exactly where to look you can just about see it on some subjects. Previous to the firmware upgrade I made a hot pixel mask in photoshop and used that with the dust and scratches filter, see: http://www.rangefinderforum.com/forums/showthread.php?t=5854

If I overlay that mask on pictures taken after the firmware upgrade on subjects with detail that's fine and regular you can sometimes make out where the interpolation has been done. Without the mask for guidance and pixel peeping you'd not be able to find it.

Also, most hot pixel problems only appear on jpegs, many RAW converters map them out automatically. Unfortunately Epson's does not 🙁

Bob.

 

[Didier]

I absolutely don't know how it works. I believed HOT pixel and DEAD Pixel are not the same? Dead Pixels are on LCD screens (black spots - dead transistor cells), while hot pixels are on sensors and going mad (sending to much informations). Really don't know maybe other members have more to tell about it.

What I can show is how the correction worked on my R-D1:

I had the same picture as the left one corrected, too, which was just smoothly black, but I have chosen a lighter corrected picture to look if one can see any interpolation. Difficult to say. What I am concerned, I'm quite satisfied with the correction however it works.

Didier

 

[Stephan]

Ok, it looks like a photosite is too sensitive and is spilling over onto the neighbouring ones. I don't know if that can make sense physically though 😛 Either way, looks like the correction works.

 

[Peter Klein]

I believe that a hot pixel in RAW is just a single pixel, easy to miss on the scren or a small print. In JPEG, the compression can cause a cross pattern with a small halo around it, as Didier's picture shows.

--Peter

 

[pfogle]

I've heard the term 'stuck pixel' used... I think that covers both 'hot' and 'dead' pixels. AFAIK, the transistor that drives that photosite is stuck outputting a fixed voltage - if it's 0 then it's dead, and if it's stuck on high, then it's hot. The color will depend on which element of the color mosaic filter it's under.

I suspect they're inevitable with current technology... you can even see them on the Hubble pictures!

 

[edlaurpic]

Confirmation regarding hot pixels

Confirmation regarding hot pixels

Regarding hot pixels, after you run the feature, is that it? You don't have to run it again? In other words, if you reformat your card and go out and take another bunch of shots, the new shots will not have any dead pixels?

 

[Bob Parsons]

Regarding hot pixels, after you run the feature, is that it? You don't have to run it again? In other words, if you reformat your card and go out and take another bunch of shots, the new shots will not have any dead pixels?

Yes, formating does not cause the pixel mapping information to be lost. However in the instructions for the R-D1s Epson do recommend you repeat the mapping proceedure at infrequent intervals - say every few months. That's because new bad pixels can appear and existing ones can change.

I would suspect if you left the battery out for a long period then you'd lose the hot pixel information.

Bob.