pixel or pixels?

Which is correct?
- 30M pixel
- 30M pixels

Thank you.

Adjective or noun?

As noun in a plural form.

I did a google search for "pixel/sec" and "pixels/sec", and the result was 9140 and 4920 hits, respectively. Which is correct? OR are they both OK?

I choose the pixel"s", but i don't know the rule.

1 mile 2 miles
1 inch 2 inches
1 pixel 2 pixels

Adjective?
I have always thought of "pixel" as a noun.

Here is what the page located at http://www.thefreedictionary.com/pixel reads:

Noun 1. pixel - (computer science) the smallest discrete component of an image or picture on a CRT screen (usually a colored dot); "the greater the number of pixels per inch the greater the resolution"

Wikipedia's definition is more complete though:
http://en.wikipedia.org/wiki/Pixel

A pixel (a contraction of picture element) is one of the many tiny dots that make up the representation of a picture in a computer's memory. Usually the dots are so small and so numerous that, when printed on paper or displayed on a computer monitor, they appear to merge into a smooth image. The colour and intensity of each dot is chosen individually by the computer to represent a small area of the picture. The example below [ http://en.wikipedia.org/upload/9/9a/Pixel-example.PNG ]shows a former Wikipedia logo with a portion greatly enlarged. The different shades of grey blend together to create the illusion of a smooth image. Note that sometimes (as in the example here) the edge pixels of text are reduced in shade to produce a less stepped look when viewed at normal size. This is called anti-aliasing.



So, I can't seem to find a definition where "pixel" is accepted as an adjective. But this does not necessarily prove it is never used this way. I know of an adjective formed with "pixel": "pixelised". It can be often encountered in the computer graphics related books and websites, but I have yet to see it in a dictionary. Therefore, maybe "pixel" can actually be something else than a noun. If so I would be very curious to know its definition and the case(s) where it can be used.

Yes but don't you think it cannot be considered as a measure unit? Like an inch, mile...

In the expression '30M pixel camera', the '30M pixel' is being used as an adjective to describe the noun - camera - and should not have the 's'. But without the qualifying noun, 'pixel' is the noun and should have an 's' in the plural - 30M pixels.

Thanks Andy. I have seen this expression before but I didn't realise it was used as an adjective. Sometimes you are too much focused on what the text is about to pay attention on usages that you would otherwise have found to be surprising.

Nic, as a computer graphics student I'm often told to create, say, a new 500 by 500 pixel image (I know "pixel" can be an adjective now ;-) ) in Photoshop. So, in this case, pixel is used as a measure unit.

does this mean any noun can be a adjective if it comes before a ..noun?

why is it not..3M pixeled camera..or 3M pixeling camera ..(I know it sounds odd...but)