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11-21-2008, 05:55 PM   #1
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This might be a dumb question...

but I'm having a really hard time understanding the difference between noise and pixels showing in a picture. Can anyone help me to better understand this. If I'm blowing a picture up (on the screen) and it starts getting "noisy", is that noise or pixels? Thanks.
Michelle

11-21-2008, 06:26 PM   #2
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In the simplest of terms, pixels are the dots that make up a picture. Each dots represents data that is combined to make up what we see. If that data is corrupted or distorted, then the combined picture looks wrong and messy and that is called noise. The values of the data making up the picture in one dot is greatly different to the dots that surround it.

Like tuning a tv, when the settings are right, you get a clear picture but if it is tuned a little too far one way or the other distortion starts to appear until all you see is fuzz. That fuzz is white noise from the radio spectrum.

Same with the sensor on your camera, push the settings beyond the capability of that sensor, then noise starts to appear. Also if you adjust the data from a taken picture beyond the limits of the data contain with in it, noise will appear.

Therefore,

Pixels are the dots that make up the picture.
Noise is the distortion that exists amongst those dots to give a clear picture or not.
11-21-2008, 06:38 PM   #3
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By the way there are no stupid question. You may get some ribbing but we have all had our questions. Don't hesitate to ask. Hop the answer above helped.
11-22-2008, 11:53 AM   #4
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Hey, that was very well put by Livewireshock, even me and I'm pretty dense at times, understood that explaination, well done.

11-22-2008, 11:54 AM   #5
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Everything tht every shows up on your screen is a pixel. That's the only thing your screen can display. That's what your screen is made of. Thousands and thousands of pixels - small dots of color. Pixels aren't a bad thing - there's the only thing a picture can ever contain. It seems somewhere you might hve gotten the impression that "pixels" were bad. They aren't, any more than "cells" are bad in our body. But of course, some cells are supposed to be there, and some - like cancer - are not.

Noise is what we call pixels that are basically the wrong color. The little colored specks we see in certain areas of a picture shot at high ISO or pushed too far in post processing. There were going to be pixels there anyhow - that's all a picture ever is - but if they look like colored specks rather than normal skin tones or whatever, that's noise. To make a fairly rough analogy, noise are "cancerous" pixels.
11-22-2008, 01:05 PM   #6
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Okay, I think I get it. So pixels and noise are pretty much the same because, if I understand right, noise is basically a pixel gone bad right? So if someone says "man that picture has a lot of noise", they could have just as well said, "man, that picture is so pixely". If that's true, then thank you thank you for the explainations!
11-22-2008, 04:28 PM   #7
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QuoteOriginally posted by mchud Quote
Okay, I think I get it. So pixels and noise are pretty much the same because, if I understand right, noise is basically a pixel gone bad right? So if someone says "man that picture has a lot of noise", they could have just as well said, "man, that picture is so pixely". If that's true, then thank you thank you for the explainations!
Pixels and noise are not the same any more than cells and cancer are the same. True, all noise is made of pixels, just as all cancer is made of cells. But the non-noisy parts of a picture are also made of pixels, just as the non-cancerous parts of our bodies are made of cells. It *is* true that noise is "pixels gone bad", just as cancer is "cells gone bad". But the emphasis in both cases is on the "bad" - most pixels are not noise, just as most cells are not cancer.

Saying, "man, that picture is so pixely" is a non-statement. There is not a digital pictures in the world that contains anything *but* pixels, just as there is not a living being anywhere in the world that contains anything *but* cells.
11-22-2008, 06:22 PM   #8
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How funny. And here I thought I was understanding. After rereading though, I think I do get it. Thanks for taking the time to answer for me!

11-22-2008, 06:35 PM   #9
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By the way, underexposure tends to bring on noise. Try to keep your histogram within the left border just as carefully as you prevent blowing highlights on the right.
11-23-2008, 06:48 AM   #10
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If you stay with the analogy you could make a comparison between noise and music. Music is pleasant and harmonious, constructed of individual notes in a melodious sequence, whereas noise is unpleasant and harsh and the individual notes are distorted because they're too loud or all jumbled up or there are many notes missing. So with your digital pictures. A well-taken shot is pleasant to look at and has all the pixels in their rightful places to create an image that looks real. A noisy picture has areas that may have pixels where they don't belong, that don't combine well and create distortions of colour or image. You can still recognize the image (a face, a landscape, whatever), but it's like looking through a window that hasn't been cleaned for years.
Hope that adds a little more to what others have already said.
12-02-2008, 12:59 PM   #11
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Pixelated, maybe?

Pixelation- to quote wikipedia: (link is here)

" In computer graphics, pixellation (or pixelation in American English) is an effect caused by displaying a bitmap or a section of a bitmap at such a large size that individual pixels, small single-colored square display elements that comprise the bitmap, are visible to the eye. A picture that this has happened to has been pixelated. "

You can view this effect yourself by opening an image in any photo viewer, and zooming into the image to a very high magnification level- this of course will depend on the resolution of the image itself, but a standard web photo at around 600x400 pixels will display the actual pixel blocks when zoomed into around 1200%.

Pixelation of a printed image can occur when the the source image to be printed is at a resolution that is very low compared to the printed page size. This is similar to "zooming in" on a computer screen- you're representing the image on a printed media in a fashion that allows you to see the actual pixel blocks that make up the image, because the image was at a small pixel dimension to begin with, printed on paper that is much larger than the printable dimensions of the original image.

Just my two cents worth....
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