What does pixel size mean? Can the corresponding pixels be enlarged into photos of different sizes?

Pixel is the abbreviation of image element and the most basic unit of electronic image signal.

Digital image recording technology must use electronic photosensitive devices. At present, only CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) can undertake this photoelectric conversion. They are composed of hundreds of thousands to tens of millions of independent photosensitive elements, which are closely arranged in a matrix. Each photosensitive element has the ability to convert light into charge. When its surface feels the light, it will transfer the generated charge to the signal processing chip.

"Effective pixel": The pixel value actually used in the total pixel value is called "effective pixel value".

The so-called "interpolation pixel" or "maximum pixel": let's talk about "interpolation" first. Interpolation is to artificially give a new value to a certain position in the known data for a certain purpose according to the changing characteristics of the surrounding data, so that the original data changes more coherently.

Theoretically, there can be infinitely many "interpolations" between known values, just as there can be infinitely many >: 1 to.

There are many interpolation algorithms, such as arithmetic average, geometric average and its weighted average, network function average and so on. The calculation range can be divided into circular domain and square domain. The circular domain is searched according to the radius, and the calculation units of the square domain are 2×2, 4×4, 6×6 and 8× 8.

Interpolation can be divided into interpolation method and extrapolation method.

For CCD, because the photosensitive elements are arranged tightly and regularly, simple arithmetic average can only be used.

Knowing the above, we know that the so-called "interpolation pixel" is to insert some unnecessary "pixel" values between the existing pixel values. Its function is only to feel that the mosaic effect is not so obvious when the image is enlarged beyond the actual size set by the machine, but its blur degree has not improved at all. In other words, "interpolated pixels" and "nominal interpolation" have no contribution to improving the resolution of the image. No matter how much' nominal' interpolation, its horizontal resolution is always based on the effective pixel of photoelectric conversion. Optical resolution is based on effective pixels. The more effective pixels, the better the image quality. Merchants hype "interpolation pixels" is maliciously misleading consumers.

When shooting with a digital camera, not all pixels of CCD will be used, but some pixels will be used according to the shooting size. When the shooting size with large pixel value is selected, the pixel value occupied on CCD will also increase, and the occupied storage space will also increase.

The shooting size can be freely selected from the maximum size to the minimum size set by the digital camera according to actual needs. For example, 1600× 1200 pixels or 3264×2488 pixels and so on.

The size of a "printed" digital photo is related to the shooting size of the photo, which is not only limited by the number of pixels, but also related to the resolution selected when printing. For photos with the same pixel size, the photos with low resolution are larger than those with high resolution, but they are not as fine, rich and clear as dpi. Ming Rui.

The specific dimensions are compared with the following table:

The maximum size of a pixel with a pixel specification of 200dpi is the maximum size with a pixel specification of 300dpi.

2 million 1600× 1200 8 inches (6×8 inches) 5 inches (3.5×5 inches)

365438+ million 2048×153610' (8×10 inch) 7'(5×7 inch)

4.3 million 2,400×180012' (10×12 inch) 8'(6×8 inch)

5 million 2560×192012' (10×12 inch) 8'(6×8 inch)

6 million 3,000× 200014' (114 inch) 10'(8× 10 inch)

8 million 3264× 248816' (12×16 inch) 10'(8× 10 inch)

1 1 4080×2720 20'( 16×20 inches) 12'( 10× 12 inches)

144,536× 3024 24 ft (18×24 in) 14 ft (1 1× 14 in).

Through the above analysis, we can know that "pixel" is related to the following aspects:

1. When you buy DC, you should know the size of the photosensitive device, that is, the size of the CCD. Not as big as small. The more total pixels, the better.

2. Don't listen to the merchant's "interpolation pixel" or "maximum pixel" and "nominal interpolation". That's all rubbish!

3. When setting the pixel specification when taking photos, we should consider the need of "printing" and lower the pixel specification appropriately so that the memory card can store more digital photos. Generally, it is enough to print 5-7 inches of photos at home (unless you plan to enlarge them when taking pictures, try to set them as large as possible. Although it takes up more pixels, it can maintain the enlarged image quality).

4. When printing, on the premise that the pixel specifications can meet the requirements of high resolution, try to choose high resolution, so as to ensure that the details of the photos are more delicate.