View Question
Q: Pixels? ( Answered ,   1 Comment )
 Question
 Subject: Pixels? Category: Miscellaneous Asked by: seattle-ga List Price: \$5.00 Posted: 21 Jan 2003 20:26 PST Expires: 20 Feb 2003 20:26 PST Question ID: 146810
 ```Greetings Google Researchers. If anyone out there is watching the various questions I ask, they will probably be saying --- that guy should go to school! They are correct, but it is easier to ask for instant knowledge from the great Google Answers gang. This time I am asking for help understanding PIXELS. Am I correct that a pixel is a dot of light? For example, if a manufacturer says "active matrix screen supports a resolution of 1600 by 1024 pixels" how can I translate that into size of the screen? Is there a set number of pixels per inch? If not, what determines the number of pixels per inch? Please give me a primer on this so that I can understand how pixels, resolution, and screen size all fit together to determine the quality of picture one will see on their monitor. Thank you.```
 ```Hi seattle-ga, Hmm..GA better than going to school? Looks to me that you just want an excuse to bunk classes. ;-) Anyways, its great to have you back. Lets see if we can satisfy your curious mind this time. What is a PIXEL? ===================== The name Pixel stands for a PICture ELement. A pixel is a single point in a graphic image. You can consider it the smallest piece of information we store about an image. Graphics monitors display pictures by dividing the display screen into thousands (or millions) of pixels, arranged in rows and columns. The pixels are so close together that they appear connected. Image/Screen Resolution ======================== When we talk of the resolution, we are referring to the number of pixels that make up the image. Common screen resolutions are : 640x480, 800x600 etc. As you can see, the resolution is described as (the number of pixels available horizontally) x (the number of pixels available vertically). How does Resolution affect quality? =================================== Simple! Higher resolution = better quality. If you have a higher resolution image, that means you are using more pixels to make up the image. More pixels = more information = better quality. How Many Pixels in an inch? =========================== There is no answer to this question. A pixel has no predefined size. Think of a pixel as a dot. You can draw a one inch dot or you can draw a 1 mm dot. This is why you cannot determine screen size from the screen resolution. A 14 inch monitor can display the screen at multiple resolutions eg. 640x480 or 800x600. The size of a pixel displayed by it at the 800x600 resolution is smaller than the size of the pixel it uses at 640x480, but the overall screen size(14 inch) remains the same. As you can see, the number of pixels per inch(ppi) determines the screen resolution. Higher ppi = Higher resolution Another thing to note is that the number of ppi(and hence the resolution) affects the size of the images and text being displayed. An image of size, say, 100x100 pixels will appear larger at a lower resolution of 640x480, than at a higher resolution of 800x600, due to the lower ppi value at 640x480. Colour Depth ============ A very important component of image quality, is the Colour Depth. Colour depth can be defined as the number of bits being used to store colour information for a pixel. The larger the bit depth, the more colours a pixel can take on. More colours = Better quality. The table given below shows some of the common colour depths available, and the number of colours they allow : Colour Depth - Number Of Colours 1 2 8 - 256 16 - 65535 24 - millions of colours Screen Size ============ The monitor screen sizes are determined by the manufacturers, and do not affect pixel size as such. However, small screened monitors (such as 14/15 inch ones) are not capable of displaying high resolution(say 1600 by 1024) images, because then the number of pixels per inch(ppi) will be very large and hence, the size of a pixel too small to be useful. This is why people prefer large screen (17 inch and above) monitors. Picture Quality =============== All the metrics defined above go into defining your picture quality. A large screen size would mean that even at high resolutions, the pixel size won't become too small, and this will result in a clearer picture. Higher resolutions are obviously better, because higher resolution = larger number of pixels making up the image = Better quality. Larger colour depth allows your image to have more shades of colour, thereby improving quality. So, for improved viewing pleasure, use a large monitor (17 inch and above), set to a high resolution (1024x768 or higher) and high colour depth(16 bit or more). Some extra readings ==================== - Computer Graphica : What Is a pixel ? ( http://www.computer-grafica.com/d16.asp ) - PhotoELF - What is a Pixel ( http://www.photoelf.com/support/faq/pixel.shtml ) - Understanding Monitors:Controlling Pixels, Resolution & Screen Size ( http://www.smartcomputing.com/editorial/article.asp?article=articles%2Fpctoday%2Ftips%2F970134a%2Ehtml) - Screen Size and Resolution ( http://lowendpc.com/tech/resolution.shtml ) ========================================= Well, hope this helps. If you need any clarifications, just ask! Regards, Theta-ga ========================================== Google Search Terms Used : "What is a pixel" "what is dot pitch"```
 seattle-ga rated this answer: `I now understand PIXELS!!! Thank you theta!!!`
 ```heres some other junk you might find useful: There are some standard pixel DPI's. 72 seems pretty common, I've seen 75, and some new systems are 96. if you ever see 'dot pitch', that refers to the border space between pixels. The lower, the better. '.28' used to be pretty common, '.25' was better. I've seen '.29' on some crappy newer ones, and the Hitachi Elite 19" professional monitor I bought the other day has a surprisingly good '.22'. Pixels are not necessarily square. Some unix systems have nonsquare pixel monitors.```