Two nights ago was full moon. I looked out the window and there it was, bright and round, and illuminating the edges of the clouds surrounding it. What a nice sight, I thought, and snapped a few shots just as the clouds started to obscure it. When I downloaded the images and viewed them all at full size, I found some bright dots which I initially thought were stars. However, the same dots appeared in all the other images as well ? same colour, same spot. A search with Google revealed that these are hot pixels.
Hot pixels are those that appear as bright dots in the image in long exposure, especially in low light and night shots. The CCD, which captures the image, consists of millions of light sensitive elements. Hot pixels usually occur when the CCD is heated up after prolonged use, resulting in charge leakage in some of the sensors. This makes the particular pixel brighter than the surrounding ones and shows up as white, red or green dots in an otherwise dark background.
Most if not all digital cameras have hot pixels. This anomaly can be removed by remapping the CCD. Remapping simply hides the odd pixels by masking it with the colours of the adjacent pixels. The camera has to be sent back to the manufacturer to be remapped. It can also be reduced by using the noise reduction feature available in most digital cameras. For the moment, I can live with those odd dots which appear only in images taken with slower shutter speeds. These defects are nothing that photo editing software cannot correct.
Apart from hot pixels, the CCD is also plagued with stuck pixels and dead pixels. In stuck pixels, the particular sensor is always on, producing a bright dot irrespective of shutter speed and aperture size. This usually appear as red, green or blue in the image. Dead pixels appear as black dots because the sensor is always off, thus not registering any light. This normally turn up as black dots in images taken in bright condition.
The LCD screens are also afflicted by these defects. This is unavoidable because the elements weaken as they age and start to malfunction. I have no complaints regarding this problem as this Nikon Coolpix 3100 has served me well, having captured over two thousand images and is still doing fine generally. The only gripe I have is that the battery power is exhausted fairly quickly and I usually have to carry a few set of spares every time I go out on a shooting spree.
13 thoughts on “Hot Pixels”
er… ah… erthis is all greek to me. 😉
But it was written in plain English!
A bit too much technical jargon here for me to understand but damn, I wished I had a digicam! Contributions, anyone? 😀
You will understand when you have used a digicam long enough and discover those annoying little dots in all your images.
I luv the pic 🙂
Why because i luv 2 sketch n draw fantasy and spiritual images ,so the moon n clouds are almost always in the background.Your pic is one of the best images ive seen in a long time.
Thanks 4 sharing it 🙂
You are welcome and thank you.
didn’t understand a word you were saying 😉 but the picture though is beautiful.
thanks for dropping by my blog, man! cheers!
My writing is that difficult to understand huh? But I am glad you found the picture interesting. Have a nice day.
Thanks to you and the pic, i was inspired to pick up my pencil and finish a rather large canvas.
Until today i hadn’t sketched or painted n e thing for a month .
Thanks again 🙂
You are welcome, again. It has been a long time since I have used a pencil to sketch anything. I used to like still-life and portraits. Now you have stirred that in me again. I should thank you, too.
Question – Why did the chicken cross the road?
To get to the other side.
It is the nature of chickens to cross roads.
Arthur Andersen consultant:
Deregulation of the chicken’s side of the road was threatening its dominant
market position. The chicken was faced with significant challenges to create and
develop the competences required for the newly competitive market. Andersen, in
a partnering relationship with the client, helped the chicken by rethinking its
physical distribution strategy and implementation processes. Using the Poultry
Integration Model (PIM), Andersen helped the chicken use its skills,
methodologies, knowledge, capital and experiences to align the chicken people,
processes and technology in support of its overall strategy within a Program
Richard M. Nixon:
The chicken did not cross the road. I repeat, the chicken did NOT cross the
In order for the chicken to cross the road safely they not only need one driver
to access the server farm if not they will hang in the middle of the road.
Why does anyone cross a road? I mean, why doesn’t anyone ever think to ask,
“What the heck was this chicken doing walking around all over the place,
I have just released the new Chicken Office 2000, which will not only cross
roads, but will lay eggs, file your important documents, and balance your
You know, I am tired of all this…’apa-nama’ chicken-chicken bisnes…the
foreign powers should stop intervening in our domestic affairs and just leave
our chickens alone…. if they want to… ‘apa nama’ cross the road, they should
be allowed to cross the road… Malaysia is a democratic country, we let our
chickens do whatever they want to do… as long as they don’t threaten the Malay
unity and try to topple the government…and if they plan to do so… we won’t
hesitate to use the ISA…
Ini semua adalah khabar angin sahaja…jangan percaya khabar – khabar angin ini
semua… biasalah ini adalah taktik pembangkang untuk memecah
belahkan perpaduan ayam-ayam semua… jangan percaya… jangan percaya….
ayyooyoo… belakang cerita lain kali, kita sude bikin banyak jembatan, itu
ayam musti guna jembatan untu lintas itu jalan lagi pun kalu itu ayam mau pigi
jalan-jalan, beritau sama saya juga, saya bolley buat lebbey banyak toll……..
Karam Singh Valia:
Seperti yang saudara dapat lihat, kelihatan ayam-ayam itu sedang melintas
jalan, mereka bukan sahaja melintas jalan malah membuang najis di atas jalan dan
ini adalah pencemaran Yang paling hebat di maya pada ini. Bapa-bapa dan ibu-ibu
ayam haruslah mengambil inisiatif untuk melatih ayam-ayam agar menahan najis
sewaktu melintas jalan, sekian saya sudahi dengan……… Ayam di jalan di
lintaskan Ayam di reban mati tak makan
I missed one?
I’ve had so many chicks, I can’t remember…
Why take a photo of the moon?
Peter, I was at the penang bloggers meetup thingy yesterday, and Lucia was mentioning your name and all, so I here I am at your page. Just wanted to say hello. The blog meetup isnt exactly one might say ‘receptive’, just me and Lucia. Aha but im glad to have made a new friend and maybe next time, with due notice, you can come along 🙂
Like your pics and it was nice knowing about the pixel thingies. The batteries- it happens, when you the recharge cycles go up the performance goes down, though it was said tha li-on batts can tahan this stuff..
Perhaps we will see more people attending at the next meet. Keep blogging. 😀
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