More pixels = better photo?

I know this is a pretty basic question but a friend of mine really made me confused. She told me that too many pixels would "crowd out" the photo, thus, the color pigments would overlap each other. That's why she suggested me not to use all the pixels available. This sounds really strange to me but I can't really convince her otherwise.
I thought that the more pixels, the sharper the photo will come out (not considering other factors like manufacturers or compression methods). Can you help me clarify this?
Thank you

I think the "color pigments overlapping" would be more of a compression issue, for example, a 5 megapixel olympus may not look as good as a 3 megapixel canon because canon compresses less, however, if you compare a 3megapixel canon photo with a 4 megapixel canon photo, the 4 will probably look better if you zoom in.

but take my reply with a grain of salt because I just made that up.

Mr. Yuck, I almost spit out my water when I read that. Thank you! :-D

Having more pixels doesn't always equal a better picture. When you cram more pixels on a sensor of a given size you have to make the pixels smaller in size to fit them on the sensor. A smaller pixel is not as sensitive to light, and is susceptible to noise. So a digicam with a sensor that has pixels of 3-4 microns in size vs a dslr with pixels of 6-10 microns in size is no contest, even if the pixel count is less in the DSLR. The larger pixels in the DSLR will be able to record more light with less noise and produce a better picture.
A Canon 1D with a 4mp, 28.7 x 19.1 mm(1.3x crop factor) can produce better results than a 6mp 7.18 x 5.32 mm(typical digicam sensor, nearly a 5x crop factor)because the size of the pixels gives the quality edge to the 4mp larger sensor because of their ability to record more light with less noise. Bob Atkins has more than one article related to this subject on his website.

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Originally Posted by SangPhan

too many pixels would "crowd out" the photo, thus, the color pigments would overlap each other

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No, this is completely untrue. More pixels don't necessarily give you a higher or low quality image. It's just more pixels which you might need depending on what you're doing with the image - but it has nothing to do with image quality (which is different in this case than print quality).

Look at images posted in the other forums. They're probably only 600x400 or so in pixel dimension. They'd look the same at 3000x2000 except bigger, and you'd have to shrink it down to see it on a computer screen. Once you shrink it down, you're looking at 600x400, etc...

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Originally Posted by Jacqui

Mr. Yuck, I almost spit out my water when I read that. Thank you! :-D

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That's what I'm here for. ;)

To add a little dissent here, more pixels means greater sharpness and more detail and that is exactly what a photographer wants in some picture-taking situations. It also gives the photographer more to work with in post-processing. In a wedding shot for example you may not want to see the pores in the skin of the bride, but that level of sharpness can be perfect for the eyes.

As was mentioned, noise downgrades quality despite the pixels, but that is usually only a problem in extreme lighting conditions and often high A.S.A. such as 800 or 1600. Even then cameras like the Canon 20D practically make any noise issue disappear. There is also of course all kinds of software that will reduce noise without reducing sharpness or picture quality.

So, if the elements of design, composition and technique are equal, more pixels gives the photographer more to work with, and if he/she is talented and skilled, the result will likely be a better photo.

Ronnoco

More pixels usually means a larger print is possible. 12 MP means a bigger print than 6 MP.

However, more MP also means a harder crop is possible, and the detail is generally more natural and the photos looks "smoother." This is subjective, of course. :)

My 10D can produce images I can print at 16x20 (without cropping them), so it meets my needs. I would love a 5D, but don't have the money for it, nor can I justify buying one for any reasonable purpose. So, yes, more pixels are usually "better," but less are frequently "enough."

I've always adjusted the number of pixels based on the application I'm using the photo for and the size it will be viewed in. So, if I'm taking a photo that will be used on line and viewed in a smaller format, I take it at 2 to 3 megapixel (quicker load time too) and if it will be blown up to a bigger format for print then I take it in a 4 or 5 megapixel setting. I know I'm a little off subject here, but I thought it's worth mentioning.

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Originally Posted by Stephen Lutz

More pixels usually means a larger print is possible. 12 MP means a bigger print than 6 MP.

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True - but something to think about. It will take four times the resolution to double the print size at the same resolution. For example, 6mp DSLR's are usually about 2000 x 3000 pixels. That works out to a 6.67" x 10" print at 300dpi (it's just math). Double that print size at 13.34" x 20" and at 300dpi you'll need 4000 x 6000 pixels which would be 24mp... FWIW, I'm happy with 16x24's from my 6mp DSLR as well.

all I have to say is this...when looking at print sizes on photoshop elements for a shot taken with my 4.2 megapixel 1d, i get 34" x 23", and when I look at a shot taken with my 6.3 MP digital rebel I see 17" x 11". No settings changed or anything. Plus, you can crop the 1d shot much more and still retain a good photo. The same can't be said about the 300d. Like people have said before, it's all about the quality of the pixels.

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Originally Posted by another view

True - but something to think about. It will take four times the resolution to double the print size at the same resolution. For example, 6mp DSLR's are usually about 2000 x 3000 pixels. That works out to a 6.67" x 10" print at 300dpi (it's just math). Double that print size at 13.34" x 20" and at 300dpi you'll need 4000 x 6000 pixels which would be 24mp... FWIW, I'm happy with 16x24's from my 6mp DSLR as well.

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I only have one problem with this. A 13.34x20 inch image is actually four times larger than a 6.67x10 inch image. Not double. Let's do the math. 6x10 vs. 12x20 just to make it easy. 6*10=60 (area) 12*20=240 (area) 60*2 (a doubling) is 120, not 240. So a 4x in resolution gets you a 4x picture size. It can be confusing, but it works out.

A sensor with huge number of pixels will not do much for you, if the optics that resolve that image onto your sensor suck.

To add onto this... if your camera sensor has a huge number of pixels and the sensor size is small, then the optics need to be most excellent to fully exploit all those pixels...

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Originally Posted by greghalliday

I only have one problem with this. A 13.34x20 inch image is actually four times larger than a 6.67x10 inch image. Not double. Let's do the math. 6x10 vs. 12x20 just to make it easy. 6*10=60 (area) 12*20=240 (area) 60*2 (a doubling) is 120, not 240. So a 4x in resolution gets you a 4x picture size. It can be confusing, but it works out.

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That's what I was saying - because I've heard people refer to an 8x10 as being twice as big of a print as a 4x6, etc. I left that part out...

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Originally Posted by livin4lax09

when looking at print sizes on photoshop elements for a shot taken with my 4.2 megapixel 1d, i get 34" x 23", and when I look at a shot taken with my 6.3 MP digital rebel I see 17" x 11". No settings changed or anything.

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I'm guessing that's because the default dpi setting for each camera is different. Click on Image > Image Size and it should show that one is maybe 72dpi and a large print size, and the other might be 300dpi (just guessing on these numbers) with a smaller print size. That fact by itself really has nothing to do with image quality - it's just a default.

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Originally Posted by OldSchool

A sensor with huge number of pixels will not do much for you, if the optics that resolve that image onto your sensor suck.

To add onto this... if your camera sensor has a huge number of pixels and the sensor size is small, then the optics need to be most excellent to fully exploit all those pixels...

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Actually tests have shown that standard optics on everything from superzooms to DSLRS with the same megapixels provide much the same resolution. This is irrespective of sensor size too.

Ronnoco