Pixel is a unit of calculating digital images. Like photographs, digital images have continuous tones of intensity and shade. If we magnify the images several times, we will find that these tones are actually similar in many colors. These small squares are the smallest unit of the image, Pixel. The smallest unit of graphics can display on the screen usually a single staining point. The higher the pixel, the richer the color palette it has, and the more realistic the color is.

Pixel Definition: Pixel refers to the basic coding of basic pigments and their gray levels. 

For example, we can say that the pixels in a visible image (such as a printed page) or the pixels represented by electronic signals, or the pixels represented by digital signals, or the pixels on the display, or the pixels in digital cameras, industrial cameras (photosensitive elements). This list can also add many other examples, depending on the context, there will be more precise synonyms, such as pixels, sampling points, bytes, bits, dots, speckles, supersets, triads, fringe sets, windows, and so on.

We can also discuss pixels abstractly, especially when they are measured as resolution (also known as resolution, the same below), such as 2400 pixels per inch (ppi) or 640 pixels per line.

Points are sometimes used to represent pixels, especially computer marketers, so PPI is sometimes abbreviated as DPI (dots per inch). The more pixels used to represent an image, the closer the result is to the original image. The number of pixels in an image is sometimes referred to as image resolution, although resolution has a more specific definition.

Pixels can be represented by a number, such as a "0.3 megapixel" digital camera, which has a rating of 300,000 pixels, or a pair of digital representations, such as "640 times 480 display", which has 640 horizontal pixels and 480 vertical pixels (just like VGA display), so the total number is 640 x 480 = 307,200 pixels. The color sampling points of digital images (such as JPG files commonly used in Web pages) are also called pixels. Depending on the computer display, these may not correspond to one-to-one screen pixels. In areas where this distinction is obvious, the points in the image file are closer to the texture elements. In computer programming, the image composed of pixels is called bitmap or raster image. The term raster comes from analog television technology. Bitmap images can be used to encode digital images and some types of computer generated art. Simply put, a pixel is the value of a point in an image, which is drawn into a line and a line into a plane. Picture sharpness is certainly not just determined by pixels.

Approximate size of each pixel

The pixel of a camera is actually the maximum pixel. The pixel is the unit of resolution. This pixel value is only the effective maximum resolution supported by the camera.

300,000 640 x 480

500,000 800 x 600

800,000 1024 x 768 5 (3.5 x 5 inches)

1.3 million 1280 x 9606 (4 x 6 inches)

2 million 16,000 x 12,000 8 (6 x 8 in 5) (3.5 x 5 in)

3.1 million 2048 x 1536 10 (8 x 10 inches) 7 (5 x 7 inches)

4.3 million 24,000 x 1800 12 (10 x 12 inches) 8 (6 x 8 inches)

5 million 2560 x 1920 12 (10 x 12 inches) 8 (6 x 8 inches)

6 million 3000 x 2000 14 (11 x 14 inches) 10 (8 x 10 inches)

8 million 3264 x 2488 16 (12 x 16 inches) 10 (8 x 10 inches)

11 million 4,080 x 2720 20 (16 x 20 inches) 12 (10 x 12 inches)

14 million 4536 x 3024 24 (18 x 24 inches) 14 (11 x 14 inches)

...

These are all about sizes.