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Tech

[Discussion] What is a 'Pixel' ?

2017-09-19 04:16:56
1665 26
Hi MI fans,
Hope everyone were doing well.

Almost everyone in this technology world know about PIXEL, but what is a Pixel ?? , actually, let's see it briefly.

Topic: Digital Imaging, Pixel

Pixel

Pixel is a point or a dot which is the smallest building block of a digital image.so it is the smallest controllable element of a picture represented on the screen.
When it seen very particularly it resembles a square. Each pixel have only a single defined colour.
The more pixels used to represent an image, the closer the result can resemble the original.


The number of pixels in an image is sometimes called the resolution, though resolution has a more specific definition.

Pixel counts can be expressed as a single number, as in a 3MP digital camera, which has a nominal three million pixels or As a pair of numbers, as in a "640x 480 display", which has 640 pixels from side to side and 480 from top to bottom (as in a VGAdisplay), and therefore has a total number of 640×480 = 307,200 pixels or 0.3 megapixels.


Resolution is just the number of pixels on the display and this property alone does not measure the quality of display.

For Example, Think of resolution (pixel density or PPI) as coffee. In a cup, the liquid is dense and the color dark and rich (pixels packed densely). Spilled on a table, it spreads out thinly and no longer looks good (your “low resolution” output).




Pixel Density


      Many of us are not aware of the importance of Pixel Density in displays. It is the thing which describes the sharpness and clarity. Pixel Density is usually measured in PPI (Pixels Per Inch) which refers to number of pixels present per inch on the display. Higher the pixel density higher is the sharpness of the content. Pixel Density is calculated based on the resolution and size of the display.

Consider the above image. The alphabet “A” on the left is displayed on screen(32 inch display) with lower resolution. The alphabet “A” on the right is displayed on the screen(32 inch) with higher resolution which delivers better sharpness.




“Resolution or Display Size
Which is important?”

High Pixel Density Vs Low Pixel Density


Pixel Density for Full-HD TV


      Consider we have a Full-HD TV with size 32 inches and resolution of 1080p (1920×1080 pixels). For the given specification, the pixel density comes to around 68.84 ppi.


E.g. Pixel Density = Root((1920^2)+(1080^2))/32=68.84 ppi


Pixel Density for Nexus 5(Full HD Display)


      Consider we have a Nexus 5 smartphone which has a 4.95 inch Full-HD display. For this smartphone, the pixel density comes to 445 ppi.


      Nexus 5 has better pixel density(more than 6 times of 32 inch TV). Does this mean that Nexus has better quality display. Yes, the smartphone do have better Pixel Density.But we cannot actually compare display of the smartphones with big 32 inch TV because the applications and usage are completely different.


What makes the smartphones to be built with higher pixel density than TVs or monitors?


      Televisions are gadgets which we see from a certain display, say 7 or 8 feet. When we are seeing a 32inch Full-HD display in a distance of 7 to 8 feet, we will feel great sharpness and clarity. If we go near the display, may be one feet near the display, we may find degradation in the quality of the image. TV displays are designed in such a way to see it with certain distance. i.e. we can see the content on the display pixellated. The human eye cannot see the individual pixels if the human is viewing the display from 3 to 4 feet distance.

      Consider in the case of smartphones, they are designed to use in just 1 to 2 feet distance. So we can feel greater sharpness only if the display has higher pixel density. So it is mandatory to manufacture smartphones with higher pixel density compared to televisions.



Know your camera MP

Now take a picture in your mobile, open details of the images, see for the resolution of the image. To know the MEGAPIXELS of the camera simply mutilple the resolution of the image, 4160*3120= 12,979,200 nearly 13Megapixel.

note: take picture in standard mode.





Print size

Now if you want to print it...

With standard setting of 300 dpi in a printer, divide the resolution by 300 i.e, 4130÷300~13.8 inch and 3120÷300~10.4 inch
If you print it on 13.8x10.4 inch sheet it looks good..

But some popular magazines, prints with 1200dpi setting on a printer, now you have print 4130x3120 on 3.4x2.6 inch size to look sharp.If you want to get print or a Movie poster, obviously you to use more MEGAPIXELS camera
eg :
40" x 60" Inches  to print not less than 150 dpi, you have to use 50 MP camera to look the poster good.

As resolution increases, the camera MP should also increase so that the images at that resolution looks property ( i.e pixel density of images increase), when it is printed as a poster.

Print size; as a general formula:


[width in pixels] / [print pixels per inch] = [print width in inches]

[height in pixels] / [print pixels per inch] = [print height in inches]


Key points:


PPI : Pixel Per Inch, is generally density of pixels in a image.

DPI: dpi, dots per inch, which is output of the printer which prints the as dots per inch,inch like 150dpi,300dpi..

Remember

PPI is related to the input, i.e digital image taken in camera.

DPI is related to output, i.e print sheet from a printer.



Comment and like below.







Thank you
Sanjay





















2017-09-19 04:16:56
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MIUI Beta Tester

Asha@63. | from app

#1

Thanks for sharing information
2017-09-19 04:42:59

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SanjayRaj1222 Author | from Redmi 4

#2

Asha@63.
Thanks for sharing information

thank you..
2017-09-19 04:45:30

Grandmaster Bunny

V. Saran | from Redmi 4A

#3

Thanks for the info
2017-09-19 05:06:46
V. Saran

Pro Bunny

SanjayRaj1222 Author | from Redmi 4

#4

V. Saran
Thanks for the info

thank you..
2017-09-19 05:12:28

Pro Bunny

SanjayRaj1222 Author | from Redmi 4

#5

V. Saran
Thanks for the info

thank you..
2017-09-19 05:12:43

Advanced Bunny

Rajkiran Allala | from Redmi Note 4

#6

thanks dear for the update
2017-09-19 05:27:25

Grandmaster Bunny

Ashoks | from Redmi 3S

#7

Thanks for sharing information
2017-09-19 05:32:46

Semi Pro Bunny

Benny.P.Thekketh | from Redmi Note 4

#8

good information indeed
2017-09-19 05:33:39

Pro Bunny

SanjayRaj1222 Author | from Redmi 4

#9

Rajkiran Allala
thanks dear for the update

thank you..
2017-09-19 05:35:16

Pro Bunny

SanjayRaj1222 Author | from Redmi 4

#10

Ashoks
Thanks for sharing information

thank you..
2017-09-19 05:35:55
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