Pixel (Pixel) - the smallest element of a two-dimensional image in a raster graphic.
Each smallest element has its own color, brightness and, possibly, transparency.
Let's see under the magnification what “ pixel grid».
For example, an image that is available is used.
The number of pixels determines the level of accuracy, detail of the image (photograph) and the resolution value.
The number of pixels is related to the volume of megapixels in the camera settings.
If the camera has 18.7 megapixel camera, then the maximum size will be 5184 x 3436 , that means the photograph will have 5184 pixels wide and 3436 in height.
Resolution
The image size in pixels measures the total number of pixels in width and height.
Resolution (Resolution) - a value that determines the clarity of the details of a raster image. Most often, it is set in pixels per inch (Pixels Per Inch / PPI).
The more pixels per measure, the higher the resolution.
The higher the resolution, the better the print quality.
Note
In Photoshop, you can look at the ratio of size and resolution of an open image by going through the "" menu (/ Keyboard shortcut " Atl + Ctrl + i»).
Consider the difference in permissions as an example.
Below is presented 2 variant photos with different resolutions.
When creating a document in Photoshop ( File - Create | | | / Keyboard shortcut " Ctrl + N") You can set the parameter" Resolution"(Resolution).
We examined the concepts of “pixel” and “resolution” in relation to bitmap images and Photoshop.
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Pixel called the smallest unit of measurement of a two-dimensional digital image. Also, a pixel is the smallest element of a display matrix dimension. A pixel is an indivisible rectangular or circular object. If we talk about a two-dimensional image, then the pixel is only a quantitative characteristic, talking about the size of the image and its clarity. In display matrices, a pixel is a quantity that speaks of its size, as well as its color characteristic.
Conclusion: a pixel is a unit of measure, has a certain size and color (in some cases).
Pixel characteristic of two-dimensional military images. Pixel size
In computer terminology, any image is usually measured in pixels. In addition to the term "pixel" you can meet the slang definition of "point".
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For example, this image has dimensions 200 × 100 pixels, or dots. This means that every square inch of this image consists of 200 horizontal dots, and 100 vertical dots. This characteristic has its own term - DPI (pixel density). One of the most important characteristics of a two-dimensional image is the pixel density, the higher it is, the sharper the image will be. This example demonstrates a 1-inch image with a different pixel density, if we draw a 1-inch oblique line along the dots (pixels) in the left image with (DPI 72), we will see something like a ladder. If we draw a slanting line along the right image with (DPI 300), we will see a smoother line, where the ladder will not be visible, due to smaller pixels. If this image is enlarged, large squares of various colors will be visible, forming the overall picture, and in the right case, the image will be sharper because it has a larger supply of pixels.
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Now consider the color response of the pixel. Each pixel can transmit only one color per unit of time, it can be color, brightness or even transparency. If we consider the pixels of the matrix of displays, it should be borne in mind that they usually consist of three subpixels, some technologies use the fourth subpixel.
The term "pixel", like many other words on the subject of computer-related topics, came to us from the English language. About what a pixel is, literally tells the translation of this word into Russian. The literal meaning is an image element. Less often in Russian, the word "elise" is used, which is a synonym for a pixel.
What is a pixel. Definition
All computer technology of our time forms an image on the display with the help of tiny elements. This is the smallest element of any picture observed on the display of a tablet or computer monitor, and gives an answer to the question of what a pixel is. This indivisible object of raster graphics can have round, rectangular or honeycomb (octagonal) outlines. In the image structure, pixels are arranged in rows and columns, like the values \u200b\u200bin a standard table.
Pixel Specifications
The number of pixels on the monitor of your device directly affects the quality and clarity of the image. The maximum resolution of the picture is set by the technical characteristics of the display, and it is impossible to change it. With multiple image enlargement, the structure of the image is clearly visible - large grains of the “atoms" of the image. Each "grain" is characterized by transparency, color and brightness. The pixels of color monitors are made up of particles called triads. The triad consists of subpixels of red, blue and green.
The number of triads for one pixel can be different - basically this characteristic depends on the type of display. The distance between two identical colors is called the point pitch. In addition to the triad, there are two more elements of information that are responsible for the location of the pixel horizontally and vertically. All five elements give a concept of what a pixel is and determine the correct color and placement of this “grain” on the screen. The set of pixels on the monitor forms one frame. If the frame is enlarged several times, you can see that each part of the image is composed of their small colored grains, that is, of pixels.
Pixels and monitor types
In LCD monitors, with proper software installation, one pixel has only one triad. CRT monitors do not limit the number of triads - for one pixel the number of such tricolor components can exceed tens.
Bad pixel
Now you can answer the question of what a broken pixel is. This is the "seed", the color of which remains unchanged, regardless of the image on the monitor. It is necessary to distinguish between broken, frozen and hot pixels.
A broken pixel is a "grain" to which power is not supplied. On the screen it is always displayed in black.
A frozen pixel does not change color and constantly glows with a red, green or blue dot in any picture that the monitor shows. The fact that a broken pixel is an invariant marriage can best be said about what a broken pixel is and how it differs from a frozen one. With a large number of broken "grains" the device must be replaced. You can try to recover a frozen pixel using special programs for this. Sometimes it takes a little time for a frozen pixel to function in normal mode.
A hot pixel is displayed on the screen in white or deep pink. It disrupted the process of supplying an electrical signal. You can "cure" it by the same means as a frozen pixel.
Camera
In a modern digital camera or movie camera, the pixels are located on the matrix. It is she who converts the incoming light flux into electronic pulses. The processor of the camera processes electronic signals into a digital code, which is recorded on a memory card. The answer to the question of what pixels are in the camera is in the structure of the device matrix. The number of pixels on the matrix affects the image quality - the more there are, the more detailed the picture.
However, there is a small but ..
The resolution of the human eye is about 2.5 megapixels. Most modern TVs and monitors have a resolution of about 2 megapixels. The question is, why then are cameras with a matrix of 16 or 14 megapixels produced?
On the one hand, this is a marketing move. A simple buyer is sure that he knows what a pixel is and is convinced that the more pixels in the camera, the better the picture. The matrix size of a camera with 2 megapixels and 14 does not differ very much. The question is, how to place seven times as many pixels on a standard-sized area? Only by reducing their size. There are more pixels, but in size they are much smaller than standard ones. So the light output of such a pixel is worse than that of a standard one. Therefore, complex frames with low or night lighting will be processed much worse than in matrices with fewer pixels. Therefore, looking after a new camera, it is not out of place to pay attention not only to the number of pixels, but also to the size of the matrix.
What are pixels in a photo?
On the other hand, a larger number of pixels allows you to better process photos. The structure and clarity of the image itself depends on how many tiny particles took part in its creation. For everyday photographers, professional photographers recommend a “golden mean” - a camera with 6-8 megapixels and a good matrix of the right size.
How many pixels are contained in one centimeter - it would seem, the question is obvious, there should not be tricks here. But everything is not as simple as it seems at first glance. The fact is that a pixel is not some fixed value - it is the smallest logical element of a two-dimensional raster image, which has its own size, transparency, coordinates, color. Therefore, let us consider these pixel properties in more detail and to solve the problem we will get acquainted with concepts such as printer resolution (DPI) and monitor screen resolution (PPI).
This is how the image looks at high magnification. The small squares that you can observe in this photo are the very pixels.
The number of pixels, along with the bit depth of the palette, are one of the most important characteristics that affect image quality. All this you need to know to determine the number of pixels in 1 centimeter. The smaller the pixel, the more detailed the final image will come out. This is due to the fact that with a smaller pixel size, their number increases per unit area. Let's enter a value that characterizes the number of pixels per unit area and call it Resolution. This characteristic has four varieties, depending on the type of image conversion - DPI, PPI, LTI and SPI. The main here are the DPI and PPI values, we will consider them in more detail.
- DPI - the number of dots per inch, the type of resolution applied to printers when printing images. The larger this setting, the more detailed the image will appear when printing.
- PPI - the number of pixels per inch, used to indicate the resolution of the monitor. This value, most often, counts the number of pixels that fit on the screen of your monitor.
Thus, if we talk about images directly, it should be noted that it does not have its own resolution. This parameter is formed by the device on which the image was created. For example, if photo A is taken on a 3-megapixel camera, then its resolution will be equal to 2048 pixels wide by 1536 in height. If a 4-megapixel camera was used for picture B, then, accordingly, the resolution of such an image will be 2464 pixels in width and 1632 in height.
It is logical to further emphasize the relationship of screen resolution with image size. Take the examples described above. If we print image A with a resolution of 300 DPI, then we get a photo with dimensions 17 × 13 centimeters. If you print photo B, then it will have a size of 19 × 14 centimeters. The same trend will be observed when displaying image data on a monitor screen. Photo B will be larger than photo A.
Here you can observe the difference in the number of pixels per unit area. As you can see, despite the same size, the image on the right will look more accurate than on the left, since the PPI of the second image is larger. An interesting conclusion follows from this - the resolution in its pure form is not a measure of the accuracy and quality of the image, it only forms the final dimensions at which the picture will have the highest detail. But, given the fact that it is more convenient for people to look at larger images, we can conditionally attribute the value of this characteristic to the main one when describing the degree of detail.
Here is a good example, showing how at the same size, but different resolution images will look when printed. It’s time to get acquainted with the principle of determining the pixel size of 1 cm.
Determining the number of pixels in 1 centimeter
Before you get acquainted with the above terms and patterns, you probably were only concerned with one question - the number of pixels per 1 cm. Now you understand that the number of pixels per unit area, that is, resolution, is not a fixed value. And it depends on the size of the pixel itself, moreover, it is a variable when it comes to outputting pictures to flat media.
Well, how to determine the size of the pixel? In fact, this question is very tricky. After all, such a thing as “pixel size” does not exist. A pixel is not an independent quantity — it is part of the relationship between screen resolution, the physical and pixel size of a given display. Any pixel properties are set by the device in which the image is processed. But, precisely from here, from this definition, a formula follows that allows you to determine the number of pixels per unit area, that is, the PPI resolution:
P / U \u003d R, where P is the pixel size of the screen, U is the physical size of the screen, and R is the number of pixels per inch.
For example, one of Apple's Mac Cinema Display 27 screens has a physical width of 23.5 inches, its pixel width is 2560. Based on this data, we can calculate the pixel density per inch:
2560 / 23.5 \u003d 109 pixels per inch of this display. Let's try to convert this value to centimeters:
1 inch \u003d 2.54 cm, therefore, 109 / 2.54 \u003d 42 pixels per centimeter, so we calculated how many pixels there are in one centimeter of this screen.
The figure shows various degrees of image density, according to which you can navigate in terms of creating an optimal photo for resolution. Formula No. 2 for calculating PPI
There is an alternative formula that also allows you to determine PPI. To do this, we need to know the diagonal of the screen:
[√ W ^ 2 + H ^ 2] / D \u003d R, where W is the width of the screen in pixels, H is the height, and D is the diagonal expressed in inches. I propose applying this formula to the above example:
- Since the aspect ratio of the Mac Cinema Display is 16: 9, and the pixel width is 2560, we can calculate the height of the display from here:
(2560/16)*9=1440;
- The diagonal of the screen we are considering is 27 inches;
- We substitute these values \u200b\u200binto the formula and find the pixel density per inch:
[√2560 ^ 2 + 1440 ^ 2] / 27 \u003d 109 PPI, that is, the same 42 pixels per centimeter.
Using these formulas, you can calculate how many pixels are in one centimeter, provided that the photo is taken using a digital device, such as a camera. Printing uses a completely different resolution called DPI. Using it, you can calculate the final image size when displaying it on flat media, which can be useful in practice, for example, if you are fond of photography.
How to determine the size of the photo when printing
So, for starters, I propose to calculate how many pixels are per centimeter when displaying an image on a flat medium. Typically, printers have a resolution of 300 DPI. This means that there will be 300 dots per inch of image. Dots and pixels are not always the same thing, because some printers print dots without mixing colors, which requires more dots in order to display a pixel. However, knowing this option helps determine the size of the image being printed. In order to find out, the following formula is used:
X \u003d (2.54 * p) / dpi, where x is the length of the side of the photo, 2.54 is the number of centimeters in one inch, p is the pixel size of the side.
For example, we need to print a photo with a resolution of 2560 x 1440. The resolution of the printing device is 300 dpi. We use the formula to determine the dimensions of the flat media onto which this image will be printed.
- X \u003d (2.54 * 2560) / 300 \u003d 21 centimeters wide;
- X \u003d (2.54 * 1440) / 300 \u003d 12 centimeters in length.
Therefore, the size of photo paper required to print this image should be 21 x 12 cm.
Common screen resolutions and output sizes for printing images with these resolutions are presented here. Here the relationship between the pixel size, DPI and the physical size of the screen / matrix is \u200b\u200bclearly traced. 3 by 4 cm in pixels?
When printing photos, different sizes are used, 3 x 4 cm - one of them. Let's try to determine the resolution of such a photo in pixels when printing it (printer resolution is 300 dpi). To do this, we use the above formula:
x \u003d (2.54 * p) / 300, hence
p1 \u003d (300 * 2.3) /2.54 \u003d 271 - pixel width of the photo;
p2 \u003d (300 * 4) /2.54 \u003d 472 - pixel length;
Thus, this photo will contain 271 * 472 \u003d 127912 pixels.
Another table of the ratio of pixel resolution, sheet format and physical image size at the output. Conclusion
With the advent of a variety of resolutions, dots, drops, and so on, confusion began to arise in determining the pixel density, photo size, etc. But, the formulas given in the article are relevant.
If you want to know more information about DPI and PPI, I suggest you look at the videos that reveal the contents of these concepts:
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What is a pixel?
Imagine that the monitor screen is divided into many thousands of small cells, like a notebook sheet, only many, many smaller. Each such cell on the screen is called a pixel.
If the cells are very small, more are placed on the monitor screen. So, they better convey shades of color and small details of the picture. The more pixels that fit on the screen, the higher the resolution. At low resolution - pixels are smaller, respectively, their size is larger, and image quality is worse. Color transitions are made as if from a mosaic, the drawings consist of small squares. So, the more pixels and the smaller they are, the higher the resolution, the higher the quality of the pictures.
Dead pixel:
Have you ever heard the expression “broken pixel”? Surely. What does this mean? And this means that one of the cells on the monitor (LCD TV screen, computer or laptop monitor, matrix of a digital camera) ceased to conduct light. Turned off. Broke. If the screen resolution is high, then among hundreds of thousands of other cells, it will almost not be visible. At low screen resolution, it is visible as a black dot on the screen.
Hot Pixel:
Still pixels are hot. Against a plain background, they look like colorful dots, red, orange, green - any. This means that the pixel has not lost its working capacity, everything is in order with it, it just “hung” on some specific color, and cannot switch to another. Sometimes this “cures” on its own, upon reboot, if not, it is advised to massage the monitor screen in place of the “hot” pixel with a finger or a cotton swab. Only be careful not to damage neighboring pixel cells. This does not apply to cameras, the pixels of the matrix are reflected on the camera’s display, and you just won’t get to it with a cotton swab.
