P&S: sensor dust - lens dust - hot pixel?

Canon EF 28-135mm F/3.5-5.6 IS USM

08/20/2006 01:37:52 AM · #1

P&S: sensor dust - lens dust - hot pixel?

I started noticing these bad pixels, at the same place in each picture. I mainly see them when I crop in certain places. It seems to be more than just one single pixel each place, as they are quite visible on some of the pictures I take, and there are both red, white and blue ones as I can tell - different sizes as well.

Full size unedited picture here (long exposure with lens cap on): //usera.imagecave.com/KSE/SensorTest/IMG_5560.JPG. 15 sec exposure, F/2.7, 2592x1944 (maximum size).

Since this is a P&S, I suppose sensor dust should not be the case, especially since the picture is taken in full darkness - if there is no light, dust on the sensor should not be a factor, should it?

There is a small grain of dust visible inside the lens, but I think that is no factor either - it should not show at all - especially since it seems to be quite close to the front of the lens.

I have read about sensor remapping - is that what I need? Then the hot pixel programs, found one just before internet explore crashed and closed all 20 places I was looking at ... have to find it again and see if it works.

It is my Canon PowerShot S2 IS from my profile, bought it december 2005, and have shot around 15500 pics by now (!)

Comments .... please!

Message edited by author 2006-08-20 01:38:37.

I Enjoy Ham

Canon EOS-30D

08/20/2006 01:47:40 AM · #2

just seems like some hot pixels to me... but im not a pro :)

-Dan

aliqui

Nikon D300s

Nikon AF-S Nikkor 70-200mm f/2.8G ED VR II

08/20/2006 01:50:05 AM · #3

I'm a pro! (Thanks to my same question a few weeks ago, heh)

//www.dpchallenge.com/forum.php?action=read&FORUM_THREAD_ID=443594&page=1#2713598

Nikon AF Nikkor 50mm f/1.8D

08/20/2006 01:56:25 AM · #4

Fast answers here I must say!

I found this link again:

//www.mediachance.com/digicam/hotpixels.htm

Which I will try.

Is sensor remapping only for dSLRs, or also for a P&S like mine? Is it something you can have done while you wait, at repair centers in major cities - or is it only something via mail (i.e. wait for ages for your camera to regurn ...) ???

deapee

Kodak V803

08/20/2006 02:30:21 AM · #5

Originally posted by B74A:

It applies to all image sensors...whether yours can be re-mapped or not I'm not sure. You'd have to call Canon and ask. Either way, it will have to be sent out and be without it for a few weeks.

08/20/2006 02:48:59 AM · #6

Originally posted by deapee:

It applies to all image sensors...whether yours can be re-mapped or not I'm not sure. You'd have to call Canon and ask. Either way, it will have to be sent out and be without it for a few weeks.

I would have to buy myself a dSLR in the meantime, then, oh, this suffering :-)

Has anyone tried this on a PowerShot, or any Canon P&S?

Btw, I have now played a little with various utils - some are good just for night shots, and that is not sufficient.

I see two options:

1) Remap by Canon

2) Util that will remap any picture, by taking a black frame and filtering the dots in question. Not just paiting them black, but averaging from the pixels around the dead one. Preferrably automatically from all new pictures I take (DPChallenge rules??? Must be done in-camera?). Yes, I know, some of these bad pixels only show on long exposures, but as long as it is on pixel level, and nabour pixels are mixed in, it should not have any negative impact on any picture?

Does this utility exist as described above?

If it wasn't for DPC rules, a stand-alone utility like this could work for all downloaded pics. And I have an idea how to do it - solves two problems in one:

1) Rename ZoomBrowser from Canon to some other file name (have done it already since I cannot disable it to start after file download). Problem one solved - no more waiting and closing of ZoomBrowser.

2) Put util in Canon ZoomBrowser directory and rename to zoombrowser.exe

Now, all future downloads should be filtered automatically :-)

All I would need to do is to shoot a new black frame now and then, to update dead pixels ...

But, DPC rules ... this would not be legal, right?

Message edited by author 2006-08-20 02:52:00.

08/20/2006 03:41:02 AM · #7

Now testing HotPixel and BlackframeNR ... see //www.dpchallenge.com/portfolio.php?USER_ID=60165&collection_id=16929

On the full size pictures, the BlackframeNR gives better results, but to my surprise, when cropped to 640x the original is best! On her lip is a larger white pixel, and below that a red one. The red one doesn't show, as it is on her skin - almost same tone - but the white one is not taken care of at all.

For larger images, see //usera.imagecave.com/KSE/SensorTest/ as they are cropped here automatically ...

HotPixel is working in the right way, as it is more automatic, but it still does not kill the hot pixel on her lip (it is on ALL pictures I take, in the same pixel position). Also, some pictures with pinpoint lights - will it take these out as hot pixels?

I think the best solution is close to the BlackFrameNR, except it should be for all shots - not just night time, it should work better and it should be able to work automatically - on batch level.

Just found this page - just learned something new -

Hot Pixels - Dead Pixels - Stuck pixels ...

//docs.kde.org/stable/en/extragear-graphics/digikamimageplugins/hotpixels.html

Getting closer to solution maybe ... but it ends in a Linux application - DigiKam. Ima stuck in Winslows, unfortunately ...

Another page - lot's of hot-dead-stuck pixel info: //webpages.charter.net/bbiggers/DCExperiments/html/hot_pixels.html

Message edited by author 2006-08-20 05:22:19.

09/19/2006 04:36:54 AM · #8

I have the same problem on my new dSLR - Canon EOS 400D - but I have more or less solved that (should work for the 350D/Rebel XT also):

(Quote from a differnet thread:)

Originally posted by JeffryZ:

In my opinion, this should not be a major issue and is probably found on almost every digital sensor. Unless you are having a very large print made of something dark. Even then you can easily remove it with photo editing if it is visible. You will want to be careful about changing lenses though. You do not want to allow dust inside that may get on your sensor. That is harder to deal with. I wouldn't worry about a couple of pixels. If it was many or in a large enough clump to be easliy notisable, then you can be concerned.
[/url]

The red dot I have is quite large. Large enough to see on the LCD afterwards, if you zoom just a little. I should do a 100% crop and see what happens, how many pixels. Same problem on my S2 IS (see above, not solved yet). I was surprised when the shop said come get a new camera, when I expected them to just do a remap.

But they did not know what a sensor remap was, or I used the wrong terms and did a poor explanation of what I meant (don't think so though)

See

(from RAW)

and

(from JPG)

On most pictures with longer exposure times (like 1/50 and up) you can see these hot pixels, on all (uncropped and not too bright) shots I can count about 4 or 5 smaller blue ones, even after a resize ...

Why are these pixels not mapped out from the factory?

SOLUTION: I did this:

//forums.dpreview.com/forums/readflat.asp?forum=1031&message=18151631&changemode=1

... and not all, but the RED CLUSTER OF HOT PIXELS ABOVE HAVE GONE!! Two smaller, but bright blue ones are still there, but that is a minor thing ...

So if you are a new owner of 400D, try this:

1) Put lens or camera cap on, go to a dark room to be sure if you want
2) Take JPG+RAW shot, maybe at different ISO and shutter speeds, one could be 30 sec/ISO 1600
3) Press menu, go to Settings 2 tab, and press sensor Cleaning: Manual, then OK. Wait for 30 seconds or more (is this necessary?) The mirror inside opens, but since you are not removing dust, this has really no effect, but it seems that after doing this, the camera remaps the dead pixels.
4) Take another JPG+RAW shot, compare with shots from 2) - same shutter and ISO

Now, when taking some dark shots, I cannot see dead pixels on the LCD on the back any more, only when I import to the computer can I see minor single dots ...

Hope this helps other Canon dSLR users!