Digital camera pixels are generally better

Although digital cameras have gradually become the first choice for photography enthusiasts, but it has been such a rapid development, but in a few years, at the beginning of the digital camera, pixels are a brand new thing for many people. Even now, many beginners don't understand it. To help newcomers who are new to digital photography better understand digital cameras and master digital photography, here are the pixels of digital cameras.

Pixel, translated from English Pixel, short for Picture Element, is the number of points in the unit area that make up the image. Each pixel has a different color value. The more pixels in a unit area, the higher the resolution, and the better the image will be. Pixels are sometimes referred to simply as pel (short for picture element).

How much better is the pixel of a digital camera?

Choose a camera with a high pixel count, depending on the purpose. Even if the family uses it, different people or different times will have different uses.

1. Look at the computer. The number of pixels in the full HD resolution of 22 inches or more is 1920×1080=2073600 (more than 2 million). So the Chinese Foxana friend said that 3 million is enough. The web upload photo does not need to be larger than the entire screen.

2. Wash photos. There are more than 5 inches for household washing, and a lot of 7 inches for washing. For 7-inch photos, more than 3 million pixels is enough. The larger the photo area, the more pixels you need. I think that under normal circumstances, it is enough to wash small. Sometimes we also want to wash some photos into large ones, so we need to leave some allowance.

3. If you want to edit the image, the requirements for the number of pixels will be different depending on the purpose of editing. As long as it is not printed or inkjet, the requirements are not high.

Today's new camera products, even low-priced low-end products, are mostly above 10 million pixels. Therefore, it can meet the requirements of the number of pixels in the household. That is to say, you don't have to consider the number of pixels when you buy a camera.

The higher the pixel of a digital camera, the better?

It's not that the larger the pixel is, the clearer the photo is. It depends on the size of the CCD of the digital camera, the size of the photosensor, and the CCD and CMOS. The size of the photosensitive device, the larger the CCD/CMOS area, the more photons are captured, the better the photographic performance, and the lower the signal-to-noise ratio. CCD/CMOS is a component used by digital cameras for photographic imaging, which is equivalent to film in optical conventional cameras. The surface of the photosensitive member on the CCD has the ability to store charges and is arranged in a matrix. When light is felt on the surface, the charge is reflected on the component, and the signals generated by all the photosensitive components on the entire CCD form a complete picture.

If you decompose the CCD, you will find that the structure of the CCD is three layers, the first layer is the "micro lens", the second layer is the "dichroic filter" and the third layer is the "photosensitive layer".

The first layer of "micro lens"

We know that the key to digital camera imaging lies in its photosensitive layer. In order to expand the CCD's luminous rate, it is necessary to extend the light receiving area of ​​a single pixel. However, the method of increasing the daylighting rate is also likely to degrade the image quality. This layer of "micro lens" is equivalent to adding a pair of glasses in front of the photosensitive layer. Therefore, the photosensitive area is no longer determined by the opening area of ​​the sensor, but is determined by the surface area of ​​the microlens.

The second layer is the "separation filter"

The second layer of the CCD is a "color separation filter". There are currently two color separation methods, one is the RGB primary color separation method, and the other is the CMYK complementary color separation method. First of all, let us first understand the concept of two color separation methods, RGB is the three primary color separation method, almost all the colors that human glasses can recognize, can be composed of red, green and blue, and the three letters of RGB are Red. Green and Blue, which means that the RGB color separation method is adjusted by the color of these three channels. Let's talk about CMYK, which is made up of the colors of four channels. They are cyan (C), magenta (M), yellow (Y), and black (K). In the printing industry, CMYK is more suitable, but its adjusted color is not as much as RGB.

The advantage of the primary color CCD is that the picture quality is sharp and the color is real, but the disadvantage is the noise problem. Therefore, you can note that digital cameras that use primary color CCDs generally do not exceed 400 in ISO sensitivity. In contrast, the complementary color CCD has a Y yellow color filter, which is more careful in color resolution, but sacrifices the resolution of some images. In the ISO value, the complementary color CCD can tolerate higher sensitivity, generally Can be set above 800

Third layer: photosensitive layer

The third layer of the CCD is a "photosensitive sheet". This layer is mainly responsible for converting the light source that passes through the filter color layer into an electronic signal, and transmits the signal to the image processing chip to restore the image.

The conventional camera film size is 35mm, 35mm is the diagonal length, and the 35mm film has a photosensitive area of ​​36 x 24mm. Converted to a digital camera, the diagonal length is approximately 35mm, and the CCD/CMOS size is larger. In SLR digital cameras, many have CCD/CMOS sizes close to 35mm, such as the Nikon D100. The CCD/CMOS size is 23.7 x 15.6, which is much larger than the consumer digital camera, and Canon's EOS-1Ds CMOS. The size is 36 x 24mm, which is 35mm, so the imaging is relatively good.

Consumer-grade digital cameras on the market today are mainly 2/3 inches, 1/1.8 inches, 1/2.7 inches, and 1/3.2 inches. The larger the CCD/CMOS size, the larger the photosensitive area and the better the imaging effect. The 1/1.8-inch 3 megapixel camera is usually better than a 1/2.7-inch 4 megapixel camera (the latter has only 55% of the former). While the same size of CCD / CMOS pixel increase is a good thing, but it will also lead to a reduction in the photosensitive area of ​​a single pixel, there is the possibility of underexposure. However, if you want to maintain the existing image quality while increasing the CCD/CMOS pixels, you must increase the total area of ​​the CCD/CMOS by at least maintaining a single pixel area without reducing. At present, larger CCD/CMOS processing is more difficult and costly. Therefore, digital cameras with larger CCD/CMOS sizes are also more expensive. The size of the photosensitive device directly affects the volumetric weight of the digital camera. Ultra-thin, ultra-light digital cameras generally have small CCD/CMOS sizes, and the more professional digital cameras, the larger the CCD/CMOS size.

The pixels of a digital camera are divided into a maximum number of pixels and a number of effective pixels.

Maximum pixel:

The English name is Maximum Pixels, and the so-called maximum pixel is obtained after interpolation. The interpolation operation is performed by a DSP chip provided inside the digital camera, and when the image needs to be enlarged, the nearest neighbor interpolation, linear interpolation, and the like are used to add pixels to be enlarged after the image is enlarged. The image quality obtained after the interpolation operation cannot be compared with the image that is truly photoimaged.

In the market, some merchants will indicate that "the hardware interpolation can reach XXX pixels", which is the same principle, but in the image quality and sensitivity, the picture with the largest pixel can not match the resolution of the effective pixels. taking pictures.

The largest pixel, also directly refers to the pixels of the CCD/CMOS sensor. Some merchants only advertise the maximum pixel of the digital camera in order to increase sales. When the digital camera sets the image resolution, it also has the resolution picture of the highest pixel. However, the user should be aware that this is the value obtained by the internal calculation of the digital camera. When the image is printed, the impairment of the image quality will be very obvious.

Effective Pixels:

The effective number of pixels in English is Effective Pixels. Unlike the largest pixel, the effective number of pixels refers to the pixel value that is actually involved in photographic imaging. The highest pixel value is the true pixel of the sensor. This data usually contains the non-imaged portion of the sensor, and the effective pixel is the value that is converted at the lens zoom ratio. Taking Minolta's DiMAGE7 as an example, its CCD pixel is 5.24 million (5.24 Megapixel), because part of the CCD does not participate in imaging, and the effective pixel is only 4.9 million.

Digital pictures are stored in pixels (Pixel), and each pixel is the smallest unit in a digital picture. The larger the pixel, the larger the area of ​​the picture. To increase the size of a picture, if there is no more light entering the sensor, the only way is to increase the area of ​​the pixel, which may affect the sharpness and sharpness of the picture. Therefore, in the case where the pixel area is constant, the digital camera can obtain the largest picture pixel, which is an effective pixel.

When users buy digital cameras, they usually see that the merchants advertise "maximum pixels reach XXX" and "effective pixels reach XXX". How should users choose? When choosing a digital camera, you should pay attention to what the effective pixels of the digital camera are. The value of the effective pixel is the key to determining the quality of the picture.

Digital camera pixel settings and print photo size comparison table:

The pixel settings of some digital cameras and the best photo size comparison table can be selected according to the size of the photos you wish to print. If you want your digital photo to be printed as a general specification (currently the mainstream digital print is 5R, which is 5x7 inches), then 3 million pixels is enough.

The number of commonly used digital camera pixels is usually between 2 million pixels and 8 million pixels. The higher the pixel size of the digital camera is, the larger the size of the photo can be printed without distortion. However, in terms of photo sharpness, there is no difference in digital photos of more than 3 million pixels. Therefore, in order to save space for the digital camera memory card during travel, it is not necessary to take photos according to the maximum pixel setting. For example, a 5 megapixel digital camera can also be set to 3 megapixel camera, so that the same card can take a larger number of photos.