What are Pixels?

Brendan McGuigan

Pixels are dots used to display an image on a screen or printed matter. The word is a blend of the words picture and element. Usually, the term refers to pixels in a digital context, but it is can be more generalized to refer to any smallest unit of an image.

Pixels are made of individual color dots.
Pixels are made of individual color dots.

It is important to recognize that pixels are not a measure of size, though often the term is used as though they are. Many digital cameras, for example, give a measure of pixels-per-inch (PPI), which they embed in the image files created. Users then see this measurement and assume that the units have a real size that uniformly holds true.

Pixels are often thought of as square, and they usually are in the case of computer monitors.
Pixels are often thought of as square, and they usually are in the case of computer monitors.

A video monitor is made up of many millions of pixels arranged in a grid. Monitors also have a bit depth, which controls how many greys or colors each pixel is capable of displaying. In an 8-bit display, for example, each unit can display 8 bits worth of color, equal to 28 power, or 256, colors. With 24-bit displays, each of the pixels can display in excess of 16 million colors.

While pixels are the smallest complete element of an image, they are comprised of even smaller elements. In a standard RGB monitor, for example, each pixel has three dots within it: a red, blue, and green dot. In theory, these dots all converge at the same point, making them visibly seamless, but in practice some fuzziness is often apparent. The measure of total pixels in an image is referred to as its resolution, and the higher the resolution in a small area, the more difficult it is to distinguish between individual units.

While pixels are often thought of as square, as they usually are in the case of computer monitors, this is not always accurate. Many digital video standards, such as NTSC and PAL, make use of rectangular pixels with an aspect ratio other than 1:1.

The term megapixels is used by digital camera manufacturers to describe the resolution at which the cameras are capable of taking pictures. In most computer contexts, resolution is given as two dimensions, such as in a computer display resolution of 1600 x 1200, which represents a width of 1600 and a height of 1200 pixels. Digital camera manufacturers take the sum total of pixels generated by multiplying the two dimensions, so that a camera capable of producing images at 1600 x 1200 would produce a total of 1,920,000 pixels, or 1.9 megapixels.

Many digital cameras will measure the quality of their photographs in pixels per inch.
Many digital cameras will measure the quality of their photographs in pixels per inch.

You might also Like

Discussion Comments


I guess it depends on the photo size. If you can adjust the photo to have fewer pixels, then the file will be smaller. With higher definition comes bigger file sizes, so don't go too low with the pixels as it decreases definition of the photo (Just an educated guess. Don't take my word for it.).


How can I input a 2576 pixel image at a site that limits input to 2500 pixels?


A lot goes into creating things.


I purchased a Canon Power Shot A3100IS camera. I was reading the information on it. It says you can adjust the pixels. Does adjusting the pixels if needed make the picture blurry? I haven't tried it yet.


A picture taken with a 10.1 megapixel camera (at highest resolution) would take up more memory than a 7.2 megapixel camera, yes more memory fewer images stored on a given memory card.

However new memory card technology is improving this image capacity for example: with a Canon EOS Rebel Exi (12 megapixel) on a newly formatted SanDisk SDHC 8 gigabyte card at the highest resolution 12 mg. will store approximately 1,374 pictures.

For most amateur photographers this is extreme overkill, for prints up to 12 x 16 a 6 megapixel image produces excellent quality. That same Canon EOS set at 6.3 megapixels will store 2,421 images on the same 8 GB card (1,047 more pictures without sacrificing quality).

Additionally the SanDisk Extreme III high capacity 8 GB card at 12 megapixel resolution will store approximately 2,827 high-quality images (vs. 1,374). At the aforementioned 6 megapixel resolution 5,080 (vs. 2,421 on the standard card).

I have two of the high-capacity cards purchased online for less than $20 each.

In conclusion using the high-capacity card at the mid range 6.3 megapixel, it's nearly impossible to fill up the memory card in several family outings.


As a hypothesis, consider a chess board (1 foot by 1 foot) with 64 squares. Now its resolution is 8 pixels by 8 pixels (each square being a pixel). Supposing all cameras can focus only on the actual dimensions (1 foot) of the chess board.

a camera with more megapixel capability covers the same area of the chess board. But its resolution is higher, ie. there may be 16 x 16 = 144 pixels instead of 8 x 8 = 64 pixels. Storing at this resolution requires more space in terms of memory (MB).

This results in higher resolution images eating up more space.


Pixel images do take up a large amount of room as the memory card has to assign each pixel with a color. So the more pixels a photo contains the less of these you will be able to store on a memory card.


what is a reasonably priced digital camera to purchase and how many pixels should I be looking for?


I recently bought a 12 pixel Fuji digital and was told that if I take the photos at 6 pixels, I would have more room in my memory card. Doesn't that indicate that pixels take up space? pandora


im still confused...does that mean a picture taken with a 10.1 megapixel camera (for example) would take up more memory than a 7.2 megapixel camera?

Post your comments
Forgot password?