"Pixel" consists of two words: picture and element.

Is the smallest image unit, and this smallest graphic unit can usually display a single coloring point on the screen.

Pixel is the most important index to measure a digital camera. Pixel refers to the resolution of a digital camera. Depending on the number of photosensitive elements on the photoelectric sensor in the camera, one photosensitive element corresponds to one pixel. Therefore, the larger the pixel, the more photosensitive elements, and the greater the corresponding cost.

The image quality of a digital camera is determined by pixels. The larger the pixel, the greater the resolution of the photo, and the larger the print size without reducing the print quality. Early digital cameras were all below 6.5438+0 million pixels. Since the second half of 1999, 2-megapixel products have gradually become the mainstream of the market. At present, the development trend of digital cameras, pixels are like the main frequency of a PC's CPU, and there is an increasing momentum.

In fact, from the perspective of market classification, for popular products, considering the factor of cost performance, the bigger the pixel, the better. After all, a 2-megapixel product can meet most applications of ordinary consumers. For this reason, while most manufacturers pursue high-end digital cameras with high pixels, the largest output at present is still the popular mega-pixel products. Professional digital cameras have products with more than 1 100 million pixels. With the progress of CCD (imaging chip) manufacturing technology and the further reduction of cost, 3 million pixel products will soon become the mainstream of the consumer market.

In addition, it is worth consumers' attention that the current digital camera products are nominally divided into CCD pixels and software-optimized pixels, and the latter is much higher than the former. For example, a brand of Volkswagen digital camera has 2.3 million CCD pixels, while the pixels after software optimization can reach 3.3 million.

"pixel painting"

Pixels are actually made up of many points.

The "pixel painting" we are talking about here is not a dot matrix image corresponding to a vector diagram, but an icon image. This style of image emphasizes clear outline and bright color, and the shape of pixel map is often cartoon, so it is loved by many friends.

The method of making pixel map hardly uses aliasing to draw smooth lines, so it is often used. Gif format, and pictures often appear in dynamic form. However, due to its special production process, it is difficult to guarantee the style if the size of the picture is changed at will.

Pixel painting is widely used, from the picture of FC home red and white machine played as a child to GBA handheld machine today; From black and white mobile phone pictures to today's full-color handheld computers; Even the computer we face every day is full of pixel icons of various software. Nowadays, pixel painting has become an art, which deeply shocks you and me.

DPI stands for dots per inch. As the name implies, it refers to dots per inch. Usually, we use dpi as the resolution unit of scanners and printers. The higher the value, the higher the resolution. At present, the optical resolutions of scanners sold in the market are mainly 600× 1200 dpi and 1200×2400 dpi. The optical resolution of the scanner consists of two numbers, because the horizontal resolution and vertical resolution are different. The smaller number is usually the vertical resolution, which is the value we usually use to distinguish the resolution of the scanner. That is to say, a scanner with 600× 1200 dpi is usually referred to as 600 dpi for short.

The reason why the vertical resolution is relatively small is that the CCD (Photocharge Device) of the scanner is arranged horizontally and then moves vertically to scan. Due to movement, the vertical resolution is naturally worse than the fixed horizontal resolution. As for the highest resolution that the scanner can output, 9600×9600 dpi, it is the result of scanning with the maximum optical resolution and then interpolating points through mathematical operation. People often ask, should the scanner buy 300 dpi or 600 dpi, or 1200 dpi? The answer varies from person to person, depending on your purpose. If it is only used to scan photos and documents, do text recognition or make web pages and wallpapers, then the 300 dpi model is more than enough. And if you need to use a printer to scan photos (positive films) or output images, then the 600 dpi model will do. Why don't you need too high resolution to make web pages or wallpapers? This is because the resolution of the computer monitor is about 72dpi, and the actual calculation is as follows: Take 15 inch computer monitor as an example, the horizontal length of the visible area is about 1 1.2 inch, and if the display mode is 800×600, the resolution is 800/1.

For the resolution of optical mouse, some use "DPI" and some use "CPI". Specifically, both refer to the special printing unit "PI" (the number of printable grids per inch). Where DPI (dots per inch), that is, "pixels per inch", represents the number of coordinates that its optical sensor can receive every time it moves 1 inch (about 2.54 cm) on the physical surface. For example, our common mouse with a resolution of 800 DPI is that when the mouse moves 1 inch, its optical sensor can receive 800 different coordinate points, which means that the mouse pointer can move 800 pixel points on the screen. It should be pointed out that this unit is not a proprietary unit of optical mouse resolution, but a "borrowed" unit. The real unit used to express the resolution of optical mouse is "CPI(count per inch)", that is, "the number of measurements per inch", which was put forward by Agilent, a famous manufacturer of optical mouse engine. Because discrimination is actually a dynamic process, using "number" is more vivid than using "point".