Dead pixels.

[Nomar]

I end up spending some time cloning out dead pixels in my photos and I was wondering if I don't clone them out how do they affect the quality if I decide to print? Are they very visible in print? Are they more visible in larger prints than in smaller prints?

[JimL]

What are you calling dead pixels? There are a couple of programs at Mediachance which will correct hot pixels. One called Hot Pixels and the other called Black Frame (used for night shots). While you are there they have a program which imitates Kodak Watten filters that I use every so often for color adjustments.

Mediachance
http://www.mediachance.com/digicam
JimL

[dbrugge]

By "dead pixels," do you have some dead sensors on your imaging surface? Or are you referring to the "noise" that all digital cameras are subject to?

It the bad pixels are consistently in the same place (I have two Nikon coolpix with this ailment) you can take a shot with the lens cap on, desaturate the image and invert it (make the blacks white and the whites black), and drop it over each full size image as a quick and dirty fix. (This will just make white or colored pixels black, but this is often all that you need.)

If it is camera "noise," keep in mind that the amount of noise increases with:

1) the temperature of the camera (hot days make noisy pictures)

2) the iso setting (the higher the iso, the more noise)

3) the amount of compression that is applied (your image quality or jpeg settings)

4) (indirectly) underexposing the image adds noise.

As far as how much will a stray pixel show in a print? It all depends on how many pixels there are in total. If you have an image that is 300 x 500 pixels, and you print it on a printer at 300 dpi, that pixel will only be 1/300th of an inch.

But you picture will only be an inch by and inch and a half. You can enlarge the picture to say 5 x 7 and your one stray dot will now be about 1/90th of an inch. Now the dot will show up, (but your picture will be so blurry no one will really notice)

to make matters worse. If you do any sharpening, you will create a halo all the way around the bad pixel so that everyone will be sure to see it.

Point is, shoot at as high of a resolution, with as low of an iso, with as little compression as possible, and on a cold day. Then, you will have to worry much less about the single odd pixels.

[Nomar]

Hmmmm.


I call them dead pixels because that is the term that I read in Digital Camera Magazine. I'm not sure if they are called something else, it could be a British thing. But the simplest way I can explain them is that they are pixels that you camera did not fill. From what I read they are produced by all digital cameras and is something that you just have to deal with. When I zoom in on an area of solid color they are most noticeable. But I find them all over the place sometimes. I have to check and see if they are because of something to do with the lens. I have not been very good with protecting it.

DB thanks for the tip, although I can't do the lens cap trick because mine is a digi cam that retracts the lens when it is on.