What is a pixel?
jacob8513
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jacob8513 Posted messages 7 Status Membre -
jacob8513 Posted messages 7 Status Membre -
Good evening everyone!
I’m new to the forum and given my question, you can guess that I’m not a specialist! I’ve read the Wikipedia page dedicated to pixels, gone through various websites, watched explanatory videos, but I still can't understand!
So here it is: what is a pixel? My problem is that I can’t decide between image pixel and screen pixel. What I thought is that a pixel is perfectly defined once you’ve bought your LCD screen. Am I wrong? If not, how can you find its size on your computer? And the size (in pixels!) of your screen?
I read somewhere that you can change the resolution (definition?) of your screen, for example from 800 by 600 to 480 by 320. But then the size of the pixel changes, right? That confuses me.
There’s also an image on the Wikipedia page of the pixel, a zoom. Where you see the effect of “pixelation”. This also confuses me: how can zooming in on an image account for this effect? Because it seems to me that these “big pixels” (image) are still made up of “small pixels” (screen), right?
Thank you in advance for your help,
Jacob
I’m new to the forum and given my question, you can guess that I’m not a specialist! I’ve read the Wikipedia page dedicated to pixels, gone through various websites, watched explanatory videos, but I still can't understand!
So here it is: what is a pixel? My problem is that I can’t decide between image pixel and screen pixel. What I thought is that a pixel is perfectly defined once you’ve bought your LCD screen. Am I wrong? If not, how can you find its size on your computer? And the size (in pixels!) of your screen?
I read somewhere that you can change the resolution (definition?) of your screen, for example from 800 by 600 to 480 by 320. But then the size of the pixel changes, right? That confuses me.
There’s also an image on the Wikipedia page of the pixel, a zoom. Where you see the effect of “pixelation”. This also confuses me: how can zooming in on an image account for this effect? Because it seems to me that these “big pixels” (image) are still made up of “small pixels” (screen), right?
Thank you in advance for your help,
Jacob
11 réponses
Hello,
A definition to better understand the concept of pixel https://www.journaldunet.fr/web-tech/dictionnaire-du-webmastering/1203295-pixel-definition/
More here https://www.gralon.net/articles/photo-et-video/photo-et-video/article-les-pixels---definition-et-caracteristiques-2014.htm
And here https://edu1d.ac-toulouse.fr/politique-educative-31/site-ressources31/files/04-photofiltre7-resolution-definition-simplifie.pdf
Best regards.
A definition to better understand the concept of pixel https://www.journaldunet.fr/web-tech/dictionnaire-du-webmastering/1203295-pixel-definition/
More here https://www.gralon.net/articles/photo-et-video/photo-et-video/article-les-pixels---definition-et-caracteristiques-2014.htm
And here https://edu1d.ac-toulouse.fr/politique-educative-31/site-ressources31/files/04-photofiltre7-resolution-definition-simplifie.pdf
Best regards.
Indeed, some authors lack rigor.
But let's take a numerical example:
Let’s assume (often true) that the height of the screen is three-quarters of its length; the same for the number of pixels;
Example: 640 pixels horizontally and 480 pixels vertically;
and a diagonal of 17 inches (1 inch = 2.54 cm); then:
1) Definition of the screen = 640 X 480 = 307,200 pixels (But, by convention, we do not calculate the product of these two factors; we simply indicate each of the two factors with the multiplication sign between them).
2) Screen resolution: knowing the length of the diagonal, we need to deduce the length and height of the rectangle forming the screen, using the Pythagorean theorem; the calculation shows that the length of the screen = 13.6 inches and its height = 10.2 inches (indeed: 10.2 = 3/4 of 13.6; and on the other hand, 13.6² + 10.2² = 17²).
The screen resolution = 640/13.6 = 480/10.2 = 47.05... ppi (pixels per inch).
But let's take a numerical example:
Let’s assume (often true) that the height of the screen is three-quarters of its length; the same for the number of pixels;
Example: 640 pixels horizontally and 480 pixels vertically;
and a diagonal of 17 inches (1 inch = 2.54 cm); then:
1) Definition of the screen = 640 X 480 = 307,200 pixels (But, by convention, we do not calculate the product of these two factors; we simply indicate each of the two factors with the multiplication sign between them).
2) Screen resolution: knowing the length of the diagonal, we need to deduce the length and height of the rectangle forming the screen, using the Pythagorean theorem; the calculation shows that the length of the screen = 13.6 inches and its height = 10.2 inches (indeed: 10.2 = 3/4 of 13.6; and on the other hand, 13.6² + 10.2² = 17²).
The screen resolution = 640/13.6 = 480/10.2 = 47.05... ppi (pixels per inch).
To put it simply, a pixel is the smallest physical unit that a device can reproduce (screen, printer, etc.).
The "definition" is therefore the amount of pixels that make up a surface. For a screen, you have the number of pixels in width and height.
And the resolution is the "definition" in relation to a dimension (generally given in inches), that is, the number of pixels contained in 1 inch.
In this way, you can know the resolution of a screen that has 1920x1200 for a width of 55cm. 1920/55 = 34.90 per cm or 34.90 x 2.54 (1 inch) = 88.66 pixels/inch.
This is why some screens have a much higher resolution for a practically identical dimension (compare the resolution of Apple's Retina displays to that of a standard screen).
The "definition" is therefore the amount of pixels that make up a surface. For a screen, you have the number of pixels in width and height.
And the resolution is the "definition" in relation to a dimension (generally given in inches), that is, the number of pixels contained in 1 inch.
In this way, you can know the resolution of a screen that has 1920x1200 for a width of 55cm. 1920/55 = 34.90 per cm or 34.90 x 2.54 (1 inch) = 88.66 pixels/inch.
This is why some screens have a much higher resolution for a practically identical dimension (compare the resolution of Apple's Retina displays to that of a standard screen).
In a perfect 100% world, 1 "image" pixel is displayed by 1 screen pixel...
But the graphics card is capable of offering other resolution modes and 1 "image" pixel can be displayed across 4 screen pixels...
Normally, the graphics card should be configured to the screen's "native" resolution... but you might not like the size of the icons and prefer a larger display.
But the graphics card is capable of offering other resolution modes and 1 "image" pixel can be displayed across 4 screen pixels...
Normally, the graphics card should be configured to the screen's "native" resolution... but you might not like the size of the icons and prefer a larger display.
Hello,
in computing, I'm not an expert; but if you don't understand the definition of "pixel," it might be simpler for you to look at some images?
So, I suggest you go to "Images - Google" and type in "pixels" (it's essential to write it in the PLURAL):
a multitude of images with pixels will appear.
in computing, I'm not an expert; but if you don't understand the definition of "pixel," it might be simpler for you to look at some images?
So, I suggest you go to "Images - Google" and type in "pixels" (it's essential to write it in the PLURAL):
a multitude of images with pixels will appear.
Thank you very much bendrop for these three links. Okay for the first link, I understood everything. And the sentence from the third link: Displaying a digital image on the screen matches one pixel of the image to one pixel of the screen. finally helped me to see things more clearly.
But in the second link, while its author insists on the difference between definition and resolution, does he not make the same mistake? When he says: The number of pixels composing a screen determines its resolution. Because the quantity refers to the number, and the number of pixels is, by definition, the definition. But maybe he meant that once the screen is set, a given definition implies a unique resolution.
But in the second link, while its author insists on the difference between definition and resolution, does he not make the same mistake? When he says: The number of pixels composing a screen determines its resolution. Because the quantity refers to the number, and the number of pixels is, by definition, the definition. But maybe he meant that once the screen is set, a given definition implies a unique resolution.
Yes, I think I've understood now. However, I still have a doubt: in the third link posted by bendrop, we talk about the possibility of changing the display definition in Windows. I don't see what it's about: once the screen is purchased, you cannot change the number of pixels in width and height, or maybe I'm not understanding anymore..
Another remark: in the case of a screen format with L = (4/3) h, it is easier to use Thales' theorem in the calculations. The diagonal of a 4 by 3 rectangle measuring 5 gives us the equality: d/5 = L/4 = h/3.
Another remark: in the case of a screen format with L = (4/3) h, it is easier to use Thales' theorem in the calculations. The diagonal of a 4 by 3 rectangle measuring 5 gives us the equality: d/5 = L/4 = h/3.
The word pixel was invented around the 1960s, roughly at the same time as the development of screens, about 60 years ago.
The term was coined by combining "picture" and "element."
Have a great day!
The term was coined by combining "picture" and "element."
Have a great day!
Hello,
Lesson Nº1: What is a Pixel?
What is a pixel?
The enemy is stupid: he thinks we are the enemy when it is actually him!
Pierre Desproges
(Windows 10 Configuration).
To reply to someone click on Comment.
Lesson Nº1: What is a Pixel?
What is a pixel?
The enemy is stupid: he thinks we are the enemy when it is actually him!
Pierre Desproges
(Windows 10 Configuration).
To reply to someone click on Comment.
Hello,
Okay for the definition of the pixel on Wiktionary, 1969 so, super recent.
However, the explanatory video on YouTube, meh boring: a pixel is defined there as the intersection of a row and a column... but row and column are not defined. And for good reason: a row is above all a collection of ALIGNED PIXELS!
I'm looking for software to "depixelize" an image. I found this, which works well:
https://www.deleze.name/marcel/photo/transfim/pixellise/index.html
but the problem is that it reduces the image size.
What I actually want is to obtain an animation that gradually increases the resolution of an image.
(on mac and windows)
Thank you,
Jacob
Okay for the definition of the pixel on Wiktionary, 1969 so, super recent.
However, the explanatory video on YouTube, meh boring: a pixel is defined there as the intersection of a row and a column... but row and column are not defined. And for good reason: a row is above all a collection of ALIGNED PIXELS!
I'm looking for software to "depixelize" an image. I found this, which works well:
https://www.deleze.name/marcel/photo/transfim/pixellise/index.html
but the problem is that it reduces the image size.
What I actually want is to obtain an animation that gradually increases the resolution of an image.
(on mac and windows)
Thank you,
Jacob