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Author Topic: Hot/Dead pixel  (Read 7376 times)

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ShadySue

« on: September 20, 2012, 05:19 »
0
Slightly confused about whether this should be in photography, cameras/lenses or here.

I seem to have acquired a hot/dead pixel. It's bright neon orange. Having googled, I have to point out that it's not when using long exposures; I'm working on trying to capture small birds in flight (that way lies madness) and am using speeds upwards of 1/1250th.

It's dead obvious in these photos, because I have a defocussed green background, but in other pics I can't find it at all, presumably because it more nearly matches the background.

I'm guessing all I can do is make a layer with a target around the pixel, and save it out as a transparent png so that every time I import an image from RAW, I put the png over it so that I can see and eliminate the pixel.

Is there anything I can do to easily find it in RAW - sometimes I haven't found it after five minutes at 200%? Or is there another way I haven't found yet?

(Yeah, I know the obvious thing is to buy a new camera, but that's out of the question ATM, especially with sales almost non-existent.)


Wim

« Reply #1 on: September 20, 2012, 05:41 »
0
Slightly confused about whether this should be in photography, cameras/lenses or here.

I seem to have acquired a hot/dead pixel. It's bright neon orange. Having googled, I have to point out that it's not when using long exposures; I'm working on trying to capture small birds in flight (that way lies madness) and am using speeds upwards of 1/1250th.

It's dead obvious in these photos, because I have a defocussed green background, but in other pics I can't find it at all, presumably because it more nearly matches the background.

I'm guessing all I can do is make a layer with a target around the pixel, and save it out as a transparent png so that every time I import an image from RAW, I put the png over it so that I can see and eliminate the pixel.

Is there anything I can do to easily find it in RAW - sometimes I haven't found it after five minutes at 200%? Or is there another way I haven't found yet?

(Yeah, I know the obvious thing is to buy a new camera, but that's out of the question ATM, especially with sales almost non-existent.)

Sad to hear that Liz
Us stock peeps sure beat the crap out of our cams don't we ;)

Try shooting some different, very long exposures, might go away after a while.
It's not your screen is it? if so, slightly massage on and around the pixel with finger or other pointy object (I'm not kidding)

Do you use LR? you might get away by cleaning up the pixels and then use automation on your future imports, same with Photoshop actions (in app or batch)

Good luck and report back!

Wim

ShadySue

« Reply #2 on: September 20, 2012, 05:52 »
0
No, sadly definitely not the monitor. I had hoped for that!

Not LR. I wondered about doing an action in PS, then thought it probably wouldn't work, as the surrounding pixels will be vastly different colours in each photo. It's not difficult - a quick spot healing brush - once I've found the blasted thing!

Yeah, 'beat crap out of our cameras' is right. I worked out (from the file numbers) that I shot well over 1000 pics in five hours yesterday. Instantly deleted c800 (as I was going) as there was 'no bird in the image', and most of the rest are near-instant deletions. Raining today, apu, so the camera is getting a rest!

Wim

« Reply #3 on: September 20, 2012, 06:41 »
+2
To find the dead pixels fast use a new Levels adjustment layer and move the black slider all the way to the right.

Rainy Day Dream away- ( Jimi Hendrix)

ShadySue

« Reply #4 on: September 20, 2012, 06:45 »
0
Ah, thanks! That will do nicely!  :D

digitalexpressionimages

« Reply #5 on: September 20, 2012, 07:18 »
+2
Don't know what kind of camera you use but with mine I do a sensor cleaning with the lens cap on and the camera maps out the dead pixel then supplies that data with the raw file to ACR (LR does this too). Maybe that'll help.

I have something like 14 dead pixels altogether (5D Mk II).

ShadySue

« Reply #6 on: September 20, 2012, 07:36 »
0
Don't know what kind of camera you use but with mine I do a sensor cleaning with the lens cap on and the camera maps out the dead pixel then supplies that data with the raw file to ACR (LR does this too). Maybe that'll help.

I have something like 14 dead pixels altogether (5D Mk II).
Oh, mine is a 5D2 also. So I'll try that too. Tx.

Ooops, idiot question: once it supplies the data to ACR, what happens then, i.e. when you open the photo in ACR? Is it automatically magiced out?

digitalexpressionimages

« Reply #7 on: September 20, 2012, 09:12 »
+1
Don't know what kind of camera you use but with mine I do a sensor cleaning with the lens cap on and the camera maps out the dead pixel then supplies that data with the raw file to ACR (LR does this too). Maybe that'll help.

I have something like 14 dead pixels altogether (5D Mk II).
Oh, mine is a 5D2 also. So I'll try that too. Tx.

Ooops, idiot question: once it supplies the data to ACR, what happens then, i.e. when you open the photo in ACR? Is it automatically magiced out?

Yeah, the mapping data is imported along with things like white balance and all that and it fixes it. It's funny cause when I do a night shoot or something where the hot pixels are really noticeable and I open the images for a split second I see little red spots then bloop, they disappear.

Some people have reported that doing a sensor cleaning didn't help, it has for me but I guess it's not a universal cure all. Give it a try.

ShadySue

« Reply #8 on: September 20, 2012, 09:18 »
+1
Tx.  :)

WarrenPrice

« Reply #9 on: September 20, 2012, 09:57 »
0
Hearts to you both.  Really good info.

ShadySue

« Reply #10 on: September 20, 2012, 09:59 »
0
Oh yes, hearts from me too!

KB

« Reply #11 on: September 20, 2012, 10:22 »
0
Don't know what kind of camera you use but with mine I do a sensor cleaning with the lens cap on and the camera maps out the dead pixel then supplies that data with the raw file to ACR (LR does this too). Maybe that'll help.

I have something like 14 dead pixels altogether (5D Mk II).
Hey, thanks for that. I knew it did that, but I thought it worked only with Canon's software. I had no idea it worked in ACR & LR, too!

« Reply #12 on: September 20, 2012, 10:52 »
0
Dead pixel is common if you have used your camera for a while. Continuous shooting and long exposure are overheating the sensor, in addition to the normal wear and tear.

The simplest way is to send it to Canon for remapping.


 

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