hot pixels

[yaronsh]

What's the best way to deal with hot pixels? - Yaron

[Peter_AUS]

If still under warranty get the camera fixed, if not, fix with Photoshop.

[yaronsh]

If still under warranty get the camera fixed, if not, fix with Photoshop.

Does PhotoShop have a special function to get rid of hot pixels, or do you just clone it out? (I have Elements, don't think it has a special function.)

Does anyone have experience with other s/w or plugins that deal with hot pixels?

Seems that some people see hot pixels as a camera problem that needs to get fixed. Others see a handful of hot pixels as within the manufacturing tolerance of the sensor, and if you get the sensor or camera replaced, the replacement would probably have them too.
Working in the computer industry, I am inclined to believe the latter. It's along the lines of bad sectors on a disk or bad cells in a memory chip.

It seems that Canon has some way to map out hot pixels in f/w. Do any of you know about that?

(The hot pixels don't normally show up - only in dark shots longer than about 5 sec - but I do like to take night shots occasionally.)

- Yaron

[Trevor Ash]

(The hot pixels don't normally show up - only in dark shots longer than about 5 sec - but I do like to take night shots occasionally.)

Now we're getting somewhere. What model camera are you referring to? This may not be the kind of issue that is originally thought. Long exposures on some digicams produce awfully noisy results including "hot pixels". If this is the case in your example, the camera may not be broken at all.

When the Canon D30 came out, exposures past about 10 seconds would show hot pixels here and there. The technology has since improved and Canon's newer DSLR's don't have this problem anymore.

Post a photo of what you're talking about so we can all see it

[yaronsh]

Oops, forgot to mention, my camera is a Digital Rebel.

In the images below, the hot pixel was greatly de-emphasized in the process of reducing from 6MP to 480x640 for posting here. (The JPEG compression probably didn't help either, altho I used the highest compression.) To see the pixel, you'd probably have to enlarge the image several times (thereby introducing more noise).

It's a red pixel near the top-center.

All images: Canon 28-105mm USM lense, RAW mode, converted with Canon's File Viewer Utility at shot settings (Auto WB, parameter 1) to TIF, resized and JPEG-ed with PS Elements.

Image 1) 60 seconds, A=9.0, 28mm, ISO 100.
Image 2) 13 seconds, A=16.0, 105mm, ISO 400.
Image 3) Shot with lense cap on at 60 seconds, ISO 100.

(Note: The red spot in the center of #1 is not a hot-pixel - probably either lense flare or stray light.)

Of course, the hot pixel gets increasingly annoying if I pull up any shadow detail.

In the shot with the lense cap on, there is also a faint cyan pixel in the lower left - don't know if you can make it out in this reduced version.

I took shots with the lense cap on at 1/10, 1/5, 1/4, 1/2, 1, 5, 10, 20, 30, 60 sec. The red pixel began to appear at 5 sec, the cyan pixel very faintly at 20 sec.

- Yaron

[Wings]

I've found this program a while back, never tried it, but it might be interesting for you:

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

[Trevor Ash]

Oops, forgot to mention, my camera is a Digital Rebel.

In the images below, the hot pixel was greatly de-emphasized in the process of reducing from 6MP to 480x640 for posting here. (The JPEG compression probably didn't help either, altho I used the highest compression.) To see the pixel, you'd probably have to enlarge the image several times (thereby introducing more noise).

It's a red pixel near the top-center.

All images: Canon 28-105mm USM lense, RAW mode, converted with Canon's File Viewer Utility at shot settings (Auto WB, parameter 1) to TIF, resized and JPEG-ed with PS Elements.

Image 1) 60 seconds, A=9.0, 28mm, ISO 100.
Image 2) 13 seconds, A=16.0, 105mm, ISO 400.
Image 3) Shot with lense cap on at 60 seconds, ISO 100.

(Note: The red spot in the center of #1 is not a hot-pixel - probably either lense flare or stray light.)

Of course, the hot pixel gets increasingly annoying if I pull up any shadow detail.

In the shot with the lense cap on, there is also a faint cyan pixel in the lower left - don't know if you can make it out in this reduced version.

I took shots with the lense cap on at 1/10, 1/5, 1/4, 1/2, 1, 5, 10, 20, 30, 60 sec. The red pixel began to appear at 5 sec, the cyan pixel very faintly at 20 sec.

- Yaron

Thanks for the examples!

I've looked at all three and now see what you're talking about precisely. Here's a repost of your first photo that is much more obvious so eevryone can see what you're describing. All just modified levels so that it enhanced the pixel.

Now on to your original question of how to deal with them. The first thing "I" would do is call Canon with this example photo and see if there's any way they can deal with it for you so that you'll not have to worry about it again.

If they can't fix it, I'd just use the clone tool in photoshop to remove it. It should take about 10 seconds to find the hot pixel/s (if they exist) and about 10 seconds to remove them. I couldn't even see the pixel in the scaled down images myself until I played with them in photoshop.

Not to cause you any more toubles (or trivialise the ones you have), but if these were my photos I'd be much more concerned about the lens flare ruining the photo than I would be any hot pixels.

I tried searching the internet to see how "normal" hot pixels are for this camera but saw nothing that says it is. I know some have hot pixels but I couldn't find anything that suggests they all do and what percentage do. I'm sure you'd be interested in that info.

Anyway, give Canon a call and see what they say.

[yaronsh]

Thanks. I'll try calling Canon when I get a chance, see if they can tell me anything. I had e-mailed Canon tech support. The somewhat canned response assumed that I was talking about hot-pixels on the LCD display, not in the actual picture. When I responded and clarified, they said I'd need to send the camera in to have them figure it out. Huge pain. If it's in fact outside the manufacturing tolerance, I'd rather just have Best Buy replace it for me.

Not to cause you any more toubles (or trivialise the ones you have), but if these were my photos I'd be much more concerned about the lens flare ruining the photo than I would be any hot pixels.

Yah - that's another issue... Perhaps topic for another thread. One problem at a time. A hot pixel is potentially a camera defect issue, so I'd like to get that resolved first.

- Yaron