The relationship between resolution and pixels

1． What is a pixel?

To put it simply, what we usually call pixels is the number of photoelectric sensing elements on CCD/CMOS. After a photosensitive element undergoes photosensitivity, photoelectric signal conversion, A/D conversion and other steps, the output A point is formed on the photo. If we magnify the image several times, we will find that these continuous tones are actually composed of many small square dots of similar colors. These small square dots are the smallest unit "pixel" that constitutes the image.

Pixels are divided into CCD pixels and effective pixels. Most digital cameras on the market now label CCD pixels rather than effective pixels.

2. What is resolution?

When it comes to pixels, we have to talk about resolution. Because the two are inseparable!

The so-called "resolution" refers to the number of pixels expressed or captured per unit length. Like pixels, there are many types of resolutions.

The most common one is image resolution. We usually say that the maximum resolution of digital camera output photos refers to the image resolution, and the unit is ppi (Pixel per Inch)

Printing resolution is also a very common one. As the name suggests, it is the output resolution of the printer or printing device. The unit is dpi (dot per inch).

The monitor resolution is the size of the Windows desktop. Common settings are 640x480, 800x600, 1024x768...etc. Screen font resolution: PC font resolution is 96dpi, Mac font resolution is 72dpi.

Of course there will be resolutions for other output devices. Due to the wide variety, I will not explain them in detail here. Interested friends can search online for themselves.

3. The relationship between image resolution and pixels

After talking about the definitions of pixels and resolution, let us take a look at the relationship between the two. Careful friends may have discovered that pixels and resolution are directly proportional. The larger the pixels, the higher the resolution. Let’s give an example!

As mentioned above, pixels are divided into effective pixels and CCD pixels

Generally speaking, the maximum image resolution of a 2-megapixel digital camera is 1600 × 1200 = 1.92 million pixels, that is, In other words, the actual effective pixels are 1.92 million.

The maximum image resolution of a commonly referred to 3-megapixel digital camera is 2048×1536=3145728 pixels, which means the effective pixels are 3.14 million.

The same is true for the conversion of resolution and effective pixels of other pixel-level digital cameras.

It can be seen that the higher the pixels, the higher the maximum output image resolution.

4. The relationship between printing resolution and pixels

Printing resolution is related to the size of our printed photos, so it is also relatively important.

In fact, the calculation method is also very simple:

A 2-megapixel digital camera has 1.92 million effective pixels and can output a maximum photo of 1600 × 1200

Width: 1600 Pixels/300 dpi=5.3"

Height: 1200 Pixels/300 dpi=4"

That is to say, if you print with 300dpi output resolution, you can print up to 5.3×4 inches. photos, and the usual photo size is:

5 inches: 5×3.5

6 inches: 6×4

It is obvious that 200 Megapixels can print photos up to 5 inches at 300dpi.

(Note: The maximum resolution that the human eye can distinguish is 300dpi. Beyond this resolution, the human eye cannot see the difference. That is to say, there is no difference between 300dpi and 600dpi to the human eye. , so the maximum design output resolution of current printing equipment is 300dpi. Of course, everyone has different requirements for clarity. Generally speaking, most people can be satisfied if it can reach 200dpi, so 2 million pixel printing 6 In most people's eyes, the photos are still very clear)

Summary: As mentioned above, the "print size" has a great relationship with the image resolution. As long as the image resolution changes, the print will not work. The size will change accordingly, and there is a direct relationship between pixels and image resolution, so the three can be converted to each other. The most fundamental of which is pixels.

Therefore, when buying a digital camera, pixels are still an important consideration. The specific number of pixels required can be determined according to your own needs.