# What is Pixel: Definition and 37 Discussions

In digital imaging, a pixel, pel, or picture element is a smallest addressable element in a raster image, or the smallest addressable element in an all points addressable display device; so it is the smallest controllable element of a picture represented on the screen.
Each pixel is a sample of an original image; more samples typically provide more accurate representations of the original. The intensity of each pixel is variable. In color imaging systems, a color is typically represented by three or four component intensities such as red, green, and blue, or cyan, magenta, yellow, and black.
In some contexts (such as descriptions of camera sensors), pixel refers to a single scalar element of a multi-component representation (called a photosite in the camera sensor context, although sensel is sometimes used), while in yet other contexts it may refer to the set of component intensities for a spatial position.

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1. ### Pixelation of bitmap images (pixel size, pixel density, resolution)

Hello Forum, I am attempting to understand what causes pixelation when a bitmap (jpg, png, etc.) image is enlarged. Bitmap images have a resolution indicated as the number of pixels along the width and height of the image itself. On the other hand, computer monitors also have a physical...
2. ### MHB Calculating the Magnitude of Edges for 11x11 Pixel Image

Hello guys, if I have an image with 11x11 pixels and in the center of the image is a square of 5x5 pixels, with the gray level of the background 0 and the gray level of the square is 50. How can I compute the result of the magnitude of edges(intensity of the contour) given by the compass...
3. ### Java I about how to get a pixel value in Java

Greetings! Hey guys, I need help on how can I get pixel value of an image with pixels more than 100px (10x10). Here the code that I execute in order to get the pixel value try{ File f = new File ("input image location"); BufferedImage img = ImageIO.read(f)...
4. ### I Help - pixels per inch paradox

Hello, I could some help. I've reached some sort of paradox. Ultimately I'm trying to calculate the number of pixels per inch, given a pixel size of 5177 nm and extended at a distance of .7inch (.0178 meters) (A) (60 arcsecs * 0.0178 meters)/206268 = 5177nm pixel per arcmin (B) 5177 * 60 =...
5. ### Html5 <canvas> element related apps not working

Recently I want to make a image adder in html, which is just a app that add the rgb value of each pixel in simple bmp files together.It can be used to grayscales and other things. I found this website that teches how to do that with the <canvas> element in html5...
6. ### B Pixel Size of TVs: OLED & LCD Explained

Just a wild idea while watching a documentary about TV history and CRT sets etc. Just curious to know the physics. What's the smallest pixel size available today in a modern OLED or even more classical LCD (CCFL backlight) panel? Then I though about how we now can manufacture CPU's with a...
7. ### Python How to get pixel value from a color map?

I have a python code where it generates two 1D arrays, plots them using scatter plot and then draws colorbar using normalization range. How can I find individual values at those individual pixel points? HC = data["HC"] OC = data["OC"] sample = y widthmm, heightmm = 171, 233 ratio =...
8. ### A Planck 2015 CMB temperature individual pixel variance

Hi, I'm hoping someone can point me in the right direction please. I'm using the Planck 2015 CMB temperature (intensity) SMICA pipeline maps (Nside = 2048) and am trying to determine the temperature variance of each individual pixel. Variance and hit-count were provided with the 2013 CMB maps...
9. ### B Is distance continuous or "pixel" like?

Essentially I'm asking if space is divided into stepping stones, pixels if you will. Whereby the absolute minimum distance you can travel is this distance? Another way of asking about this is, if you took a finite area of space, are there infinite positions within this space?
10. ### Is pixel a representation of intensity for light at a given location?

Is pixel a representation of intensity for light at a given location?
11. ### MATLAB How can I smooth pixelated images in MATLAB?

Hi. I have this code in matlab: / / I=dlmread('C:\Users\rshah\Desktop\Polymer Project\monteCarloCode\E=1e8.txt'); F=fft2(I); F = fftshift(F); % Center FFT F = abs(F); % Get the magnitude since F is complex F = log(F+1); % Use log, for perceptual scaling, and +1 since log(0) is undefined...
12. ### I want to find the vector components of an MRI pixel -- How?

I have a Dicom Image that is interpreted as an array. Each cell is a pixel. Each pixel has a value. I want to find the vector components (x,y,z) of a pixel. Specifically, I want to find magnetic field vectors for each pixel. The image is for H1 atoms. Freq = 297, B0 = 3. How would you do this...
13. ### How to find phase values at neighboring pixel in an image?

I have computed magnitude and phase spectrum of very famous image of cameraman using fft function in MATLAB.Here,we get magnitude and phase spectrum of the whole image. But I want to find phase values of the neighboring pixels . So if given gray scale image is of dimensions 256*256 and if I...
14. ### Single photon counting pixel detectors vs CCD

Hello, I need to learn as much as I can about single photon counting pixel detectors (producing a signal for each photons hitting the detector) e.g. PILATUS. I do not understand how this type of detectors counts single photons as opposed to integrating the energy of multiple photons (CCD, MOS...
15. ### What is the difference classical pixel and quantum pixel?

Dear all, How to differ the classical pixel and quantum pixel? How to represent the quantum pixel in quantum mechanics language? Some useful references are welcome. Thanks.
16. ### What does a CCD pixel measures?

I have a got a problem regarding what a CCD pixel actually measures. Suppose I have a pixel of area dx dy. A plane wave of intensity I0 is impinging on the pixel making an angle α with the normal of pixel surface. The flux going into the pixel would be F = I0 dx dy cos(α). My question what is...
17. ### UFO or Dead Pixel? What's Flying Across the Moon?

http://www.huffingtonpost.com/2014/10/16/ufo-flies-across-moon I don't know what method is being used to keep the moon in frame, but if it's a fixed telephoto lens the black dot "UFO" could be a dead-pixel. If the 1 pixel-sized black-dot was a real object orbiting Earth , (rather than an...
18. ### Multiplexers for 500 pixel sensor

Hello, What is the best multiplexer to use if I want to manually create a 500 pixel sensor array and display it on to an LED or LCD screen? Thank you,
19. ### Energy Collected in one pixel on a CCD.

There are two telescopes observing at night. The first telescope is 0.3m and has a focal ratio of f/8. The second telescope has a focal ratio of f/4 and is 30m in diameter. They each have an identical CCD camera whose pixels are 25 microns on a side. How much energy will be accumulated in a...
20. ### Can a DIY bolometer be used to create an IR viewer for aircraft?

How is a pixel array read, such as in a LED TV, digital camera, microbolometer, etc. All of these things have an array of pixels that either transmit or receive. Each pixel must be read somehow, is this done with a multiplexer and do you need more and more multiplexers the more pixels you...
21. ### What is the story of Pixel, the rescued cat and her new NEMA P office rating?

Pixel is my cat. She'll be two this summer. She was part of a litter found without a mother. A few of her siblings had already died when they were found. She was the only female in the group and played mother for her brothers. They were all sick when they were found, and she was the last to be...
22. ### [Android] Retrieve pixel array after an image is taken

I am working on an app that needs to access an array of pixels from a picture after it is taken. The main Activity is below. I have a good amount of java experience but extremely limited experience with images past displaying them on the screen. I see the byte array being passed to the picture...
23. ### Mathematica Mathematica Calculating length from pixel count

Hello. Does anyone know of a fast way of converting pixel count into a length metric (preferably using Mathematica)? I have an imaging program that segments and measures the lengths of objects in an image, but the only parameter that I can extract is pixel count, which then can get converted to...
24. ### How Do You Convert Pixel Number to Wavelength in a CCD Spectrum Analysis?

Hey Guys, i'm a first year astrophysics student and i got given this question to answer in a practical report: Examine the spectrum of the planetary nebula derived from the diffraction grating. You will produce a colour rendering of the spectrum together with a graphical representation of...
25. ### Pixel pitch, Airy disk diameter and maximum aperture

Hi, How to determine a threshold aperture, at which the diffraction begins to limit resolution of the sensor ? Which situation reflects that point: 1) Airy disk diameter / 2 = 2 x pixel pitch http://www.outbackphoto.com/dp_essentials/dp_essentials_02/essay.html" (third pixel detects the...
26. ### What are the different formations of the RGB phosphorus in pixel?

what are the different formations of the RGB phosphorus in pixel?What shapes they take when red and green and blue phosphorus are building up a pixel.for example there is a circle that each occupies one third of its area.and maybe in thet circle there are circles or square or other...
27. ### What is the Shape and Size of a Pixel and How Does it Affect Screen Resolution?

A pixel is said to be an intersection between horizontal and vertical lines on the screen. So does this intersection have a physical shape and size and what happens when an image or video of say 1600X1200 is played on screen having resolution of 800X600 or vice versa. I have searched a...
28. ### MATLAB Reconstructing an Image from Pixel Density Using Matlab

Okay, so my professor is give us two matrices, and wants us to get back the image from which he got these to matrices. Regardless of the process (which i double checked) I have one remaining matrix that is 1 x 480 This matrix tells me the the intensity (in black and white i think) of each...

30. ### Can a Faint Star Be Detected If Its Counts Are Less Than the Noise Level?

Homework Statement after subtracting the bias level from your count, you get a value of (N). to find the noise, you calculate sqrt(N) = noise. now the question, As above, your image has a noise of sqrt(N). What can you say about the presence of a faint star in the image that has a total...
31. ### Pixel, photodiode and capacitor

Hi! I'm having trouble figuring out the difference between a pixel and a photodiode as well as a capacitor- they all seem like the same property to me! :confused: Can someone please help me?:confused: Thanx
32. ### Understanding the Difference Between Pixel and Photodiode: Expert Help

Pixel + Photodiode!help Hi! I don't know if this is the right place for this topic but I could not find "Digital Technology" elsewhere so here I go: I'm having trouble figuring out the difference between a pixel and a photodiode as well as a capacitor- they all seem like the same property...
33. ### Display resolution 128x64 pixel

Hello Forum, When we are speaking about a display resolution 128x64 pixel how can i know the active area width of this display , is it depend to the pixel it self or what ? or is it a speacial calculation from pixel to mm?
34. ### Monitor Pixel Position Reader - Real Time Output

Is there a device that can read the positions of pixels on a monitor, may be just 6 key positions and give a real time output?
35. ### How Do You Calculate the Number of Photons Per Pixel in a CCD?

A fresh question. I want to find the number of photons falling on a pixel in a CCD. A very simple model: * bigger source area gives larger response (A_s ) * when object farther away, smaller response: \frac{1}{R^2} * bigger detector area gives larger response (A_d ) * size of the lens is...
36. ### Get Pixel Color in VB.Net 2005 Picture Box

Hey! Does anyone know how to get the "color" of a pixel in a picture box, in VB.Net 2005? I want to encode things into an image, and then later pull the information out of the pixels.
37. ### Pixel Density & Component Accuracy: Does Width Matter?

The following question appeared on one of my exam papers. A CCD of pixel density 10Mpixel (1cm^-2) is used to image a component of length 10cm. Show how this does or does not meet the required accuracies of +/- 0.025mm. A similar question was asked in a previous exam where the...