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Q: What does interpolation mean in regards to digital cameras? ( Answered ,   1 Comment )
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 Subject: What does interpolation mean in regards to digital cameras? Category: Miscellaneous Asked by: mmo-ga List Price: \$5.00 Posted: 12 Oct 2004 10:11 PDT Expires: 11 Nov 2004 09:11 PST Question ID: 413722
 ```When I'm reading descriptions of digital cameras for sale online I have seen many references to the word interpolation, where the camera might be advertised only 3 megapixels but it says you can get pictures up to 6+ megapixels with interpolation, I don't understand what 'interpolation' means and would like to know more. Here's a quote from one of the websites I was looking at: "Trendy Digital Camera with 3.2 Mega pixel and Continuous 4x Digital Zoom. Image resolutions up to 6.4MP (interpolation)." Also I don't understand much techical talk, I understand that I could probably look up the definition somewhere and get it but I fear I still won't 'get it' or understand the tech talk, so I knew I could probably come to Google Answers again and find someone who understands what this is about they could explain it to me in simple and easy to understand laymans terms, thanks!```
 ```mmo-ga: You're right that there are a lot of technical definitions out there; since you asked for a lay-person's description of what interpolation really means, let me explain it in my own words instead. We'll start with the digital camera primer from "How Stuff Works": http://electronics.howstuffworks.com/digital-camera11.htm On this page (the 11th page of the primer), it briefly mentions that: "This process of looking at the other pixels in the neighborhood of a sensor and making an educated guess is called interpolation." So how does it really work? Well, think of the sensor in a digital camera as being like you standing behind a screen-door (you know, the mesh kind), and looking outside. Each square of the mesh represents one pixel. Each pixel has a different value for color and brightness. All of the squares in the mesh (ie. the entire screen door) combine to form the actual picture. Remember that each square, or pixel, can only have one value for color and one for brightness, though. So, if you took a smaller part of this screen, and stretched it to double its size, with each square still having only one color and one brightness, now all of a sudden your picture is rather fuzzy and made up of these big squares. This is where interpolation comes in. The computer in the camera looks at each of these bigger squares, and tries to divide it into four smaller squares. If it did this by just assigning each smaller square the same color and brightness as the original bigger square, though, your picture is still going to be fuzzy. So, what the computer does is it steps back (figuratively speaking), and looks at what's going on in the other big squares around the one it's trying to divide up. It tries to smooth the color and brightness changes so that the end result is that the whole picture looks smooth and less fuzzy. The problem with interpolation, though, is that it is all just guess-work by the computer. Since the value of each square is a single color and brightness, what happens if there is a piece of detail that happened to fall exactly between two of the original squares, and was not captured by the camera? Well, that detail gets lost, since interpolation can only guess at what "should be" between the original squares. Is interpolation only used in the situation you described? Actually, no. All digital cameras use a form of interpolation to function. You see, in the sensor in the camera, you actually have a grid of little individual sensors, each capable of sensing only one of either red, green, or blue. When you click the shutter, all of these sensors are simultaneously exposed to "the picture" that you're trying to take. Each sensor picks up a certain level of brightness in the color that it can detect (red, green, blue). The computer then looks at the entire grid of sensors and their values, and calculates what the value of each pixel (the squares in our screen-door example) should be. This can get very complex right away, so I won't go into any deeper level of detail than this; just remember that this is a form of interpolation used just to figure out what color and brightness each pixel should already have in the first place. Also, you'll have seen that some digital cameras have optical zoom, some have 'digital zoom', and some have a combination of the two. Optical zoom is exactly that; the optical lenses in the camera are used to zoom into the picture before the picture ever reaches the sensors, so as far as the sensors are concerned, it's like you walked closer to the picture itself. With digital zoom, though, it's all interpolation. When you ask the camera to zoom in, it simply stretches out a smaller portion of the 'big picture', and then makes educated guesses to try to fill in the details between the original pixels. Does this explanation help? If there is any part of this that is still 'fuzzy' to you, please let me know using the Request Clarification button above! Regards, aht-ga Google Answers Researcher``` Clarification of Answer by aht-ga on 13 Oct 2004 09:04 PDT ```mmo-ga: I'm glad that you found the description useful, and thank you for the tip! Regards, aht-ga Google Answers Researcher```
 mmo-ga rated this answer: and gave an additional tip of: \$2.00 ```That was a really fantastic explanation, thanks so much for taking the time to explain it to me in a way that I would understand. Melissa```
 ```What a great answer! I have a background as a computer graphics artist, and the concept of interpolation is one about which I've been asked by friends and relatives. I always tend to get too technical in trying to explain. The next time someone asks, I'm going to refer them to aht's answer.```