Hot Pixels

Hot pixel and Dark Pixel is a single cell in your CCD or CMOS sensor that failed  to carry out correct data acquisition needed to represent a pixel in digital picture. Mostly people only aware about Hot Pixels rather that Dark pixels, since hot pixels are more easy to detect or recognized in long exposure picture taken with digital camera. Dark Pixel are appear in darker pixel if you expose highlights in exposed picture. Hot Pixel often apear in bright white, red, blue or green pixel in the long exposed picture. that a look at this star trails picture taken in 30 minutes with a nikon D40x.

You can see in the image above the little white dot is the hot pixels. The upper corner of the pictures have two bright purple area that over exposed, which will appear in every single long exposure in D40x. I don't really know what is the problem, seems it not appear as the hot pixels, I have mail the nikon about this issue, but as ussual no respond. maybe I have address the wrong mail.

At first I really annoyed with all kind of hot pixel in my D40x, later on, I get used to it.Since it appears as the common issue to all digital camera sensor to date and ther is way to deal with it. Imagine 3 pixels that failed in 10 million pixels. Even in more expensive camera will encounter this problem also. And now I believe every single camera have defective pixel in their sensor. even it appear don't have any, because it is has been calibrated or programmed not to deliver the defective pixel in the final picture exposed, by the firmware from the factory.

While as the usage of the camera increased you might later discover hot pixel appear in your picture taken with your previously hot pixels free camera. this is common if it's only a few and not many many of them. So how do we know that we have hot pixel in your camera? how severe is it? it's easy, you just to follow this steps:

• Put the lens cap or body cap on your camera.
• Set the ISO numbers to the lowest first (eg, 100). 
• Turn off the noise reduction.
• Do the 30 seconds exposure.
• Examine the picture for the hot pixels.
• Repeat the steps with higher ISO.
  

If your camera have hot pixel at 100 ISO, i think you really have a bad copy product. Mine have began to clearly appear in ISO 400. So if you have some of them, don't worry, just send it to your authorized camera service center. They will do the defective pixel compensation adjusting and your camera will hot pixel free again. Your camera will  be lens caped and connected with a computer and all process will finished in minutes.

What if you don't have time to go to service center, or they have charge a large amount of money  for the repair. Well you should not worry to much, program like adobe lightroom will automatically wipe out some minor hot pixel for you, or you can manually fix it in photoshop, but both of them gonna cost you money.

Any free solution? yes there are, you can use a software call pixel fixer. It has RAW file features that will fix your raw file for the hot pixel. just check out the link.  Before you use the software you should carry out the hot pixel area identification procedure. The software will guide you thru the process. If not the pixel fixer cannot identify the defective pixel.

Well do you still worried about the hot pixels? you should not now...