What is the difference between pixel and resolution

Pixel

In English pixel, the abbreviation of image elements (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 the unit area, the higher the resolution, the better the effect of the image. Pixels are sometimes referred to as PEL (the abbreviation for picture element).

The pixel of the digital camera is divided into the maximum number of pixels and the prime number.

Max Pixel:

The English name is maximum Pixels, the so-called maximum pixel is obtained after interpolation operation. Interpolation operation through the digital camera in the internal DSP chip, when the need to enlarge the image with the nearest interpolation, linear interpolation and other operations, in the image to add the image amplification needs to increase the pixel. The image quality obtained after interpolation operation can not be compared with the image of the real photographic imaging.

In the market, there are some businesses will be marked "hardware interpolation up to XXX pixel", which is the same principle, but in the image quality and sensitivity, the maximum pixel shot of the picture is less than the resolution of the effective pixel shot.

The maximum pixel, also directly refers to the pixel of the Ccd/cmos photosensitive device, some businesses in order to increase sales, only advertised the largest number of digital cameras, the digital camera to set the resolution of the picture, do have the highest pixel resolution picture, but the user should be clear, this is through the digital camera internal operation and the value of the results, When you print the picture again, the quality of the image will be significantly impaired.

Valid pixels:

Effective pixels of the English name for effective Pixels. Unlike the maximum pixel, the number of effective pixels refers to the pixel value that really participates in the photographic image. The maximum pixel value is the true pixel of the photosensitive device, which usually contains the non imaging part of the photosensitive device, and the effective pixel is the value converted from the lens zoom magnification. In the case of DiMAGE7, the CCD pixel is 5.24 million (5.24Megapixel) because a part of the CCD does not participate in imaging, and the effective pixel is only 4.9 million.

Digital Image storage is generally in pixels (Pixel) as the unit, each pixel is the smallest area of digital image units. The larger the pixel, the larger the area of the picture. To increase the size of a picture, if no more light into the sensor, the only way is to increase the area of the pixel, this may affect the sharpness and sharpness of the picture. Therefore, in the case of pixel area unchanged, the digital camera can get the largest picture pixel, that is, the effective pixel.

When a user buys a digital camera, they usually see the merchant advertise "the maximum pixel reaches xxx" and "the effective pixel reaches xxx", how should the user choose? When choosing a digital camera, you should pay attention to the number of effective pixels of a digital camera, the number of effective pixels is the key to determine the quality of the picture.

Digital camera pixel settings and printing photo size comparison table:

Some digital camera pixel settings and the best picture size can be printed on the table, according to their own wish to print the size of the photo to choose to use. If you want your digital photos to be printed as a general specification (the current mainstream digital stamping is 5R, or 5x7 inches), then 3 million pixels is enough.

Now commonly used digital camera image primes are usually 2 million pixels to 8 million pixels. Select the higher the number of pixels of a digital camera in the image of the picture in the absence of distortion, cocoa stamping the largest size is also relatively large, but from the photo clarity, 3 million pixels above the digital photos no difference. Therefore, in order to save the space of the digital camera memory card during the travel, it is not necessary to take photos according to the maximum pixel setting. For example, a 5 million megapixel digital camera can also be set to take pictures of 3 million pixels, so that the same card can make a larger number of photos.

The following is a part of the digital camera pixel settings and the best photo size can be printed on the table, according to their own wish to print the size of the photo to choose to use.

Digital camera pixel settings Photo file resolution (pixel) to print the best picture size

	photo file resolution Rate (pixel)	Best picture size for printing
500 Million pixel	2560x1920	>12r (12x18 inch)
4 million pixel	2272x170	8r (8x10 inch)
3 million pixels	2048x1536	5R (5x7 inches)
	1 600x1200	5r (5x7 inches)
1.5 million	1280x1024	4r (4x6 inch)

Pixel setting and printing photo size comparison

From the above, you can see that if you want your digital photos to be printed as a general specification (the current mainstream digital stamping is 5R, or 5x7 inches), then 3 million pixels is enough. 3 million-pixel (2048X1536) maximum 10R photo (ie 10x14 inch), of course, slightly less effect. If your own digital photos are only viewed on the computer or posted on the website, then even if set to 1 million pixel is enough, but with the increase in the number of digital camera memory card capacity, the general 512M memory card by 3 million pixel settings, usually can be more than 400 photos, so in order to print after the consideration, It is more reasonable to choose 3 million pixels.

Resolution

Resolution is a parameter used to measure the amount of data in an image. Typically expressed as PPI (pixel pixel per inch) and dpi (dots per inch). The more data you have, the larger the length of the graphics file and the richer details. But larger files also need to consume more computer resources, more memory, larger hard disk space, and so on. On the other hand, if the image contains insufficient data (low graphics resolution), it will appear rather coarse, especially when the image is magnified to a larger size to watch. So during the creation of the picture, we have to determine the correct resolution based on the final purpose of the image. The trick here is to ensure that the image contains enough data to meet the needs of the final output, as well as the appropriate amount of resources to occupy a few computers.

When we buy a digital camera, the resolution is a very important indicator. Early digital cameras had low resolution, such as Casio's QV-10 of less than 100,000 pixels (320X240) and 180,000 pixels of Kodak DC20 (493x373), which were not as good as the current camera phone and camera. After nearly a decade of development, digital camera resolution has increased, currently more than 10 million pixels. For 2048x1536x16m, 2048x1536 means there are 2048 pixels in the width direction and 1536 pixels in the height direction. 2048x1536=3145728, we call it 3 million pixels. And the 16M behind is the color depth. Each pixel is colored, and the color of each pixel is recorded in 3 byte, red, green, and blue respectively. Each byte can record 256 levels, so it is possible to record different colors of the 256x256x256=16777216, that is, 16M, also known as 24-bit color depth. Therefore, if the RGB color record of a 2048x1536 pixel image file, it is necessary to 2048x1536x3=9437184 a byte, that is 9MB, plus file first class other information, and ultimately greater than 9MB. However, the majority of digital cameras in JPG format, this is a distortion, compression of the larger image file format, under normal circumstances, 2048x1536-pixel jpg files according to its compression ratio of different file sizes are different, about 1-2mb around. You can also calculate the file size of other pixels such as 1600x1200x16m. Thus, 2048x1536x16m and 1600x1200x16m photos, the number of pixels included is not the same, that is, the information content is not the same. If you use the same output resolution to print photos, the resulting picture size is not the same, in turn, if the output of the same size of the picture, the unit length of the image of the pixel points is not the same, that is, the delicate degree of the photo is not the same.

　Correct use of digital camera to distinguish:

Resolution is an important parameter in a digital camera, and its numerical size will directly affect the quality of the final image. At the same time, the higher the resolution of the image, the larger the size and volume of the image, and the digital camera is used as a storage device, which will make it impossible to save more photos. How to find a balance between the resolution and the amount of storage is a tricky problem. If you strive to be perfect, you only have to add multiple memory cards, or choose the right resolution for your photos.

　First, the choice of advanced users:

Resolution is an important factor affecting the effect of the image, we generally use the horizontal and vertical direction of the number of pixels can be displayed to represent the resolution, such as 1600x1200. The larger the value, the more disk space the graphics file occupies, and the more fully the details of the image are displayed. So if you're a photographer or a perfectionist, it's recommended that you choose the highest resolution when shooting. Although this will take up a lot of storage space, and also need a certain amount of time in storage, but these in exchange for beautiful images, everything is worthwhile. And the large image in the post-processing also left you large enough space, large images can be appropriately reduced, and small images to enlarge on the difficulty, because the image information can not be recovered. This way you have to prepare some more memory cards, for these people, quality is the key.

Print publishing also has a high demand for images, generally for the minimum image accuracy requirements of 300dpi (dotperinch, the meaning of the printed dots per inch, the higher the value of the printed image will be more detailed and sophisticated), then the resolution of the picture at least 5 million pixels above, That is to 2560x1920, this temporary only professional level of the camera to achieve the requirements, the general digital camera is not up to. Of course, this choice is not unique, depending on the size of the photos posted on the page and the number of printed lines.

　　Second, the choice of ordinary users:

In contrast, if you're shooting a picture for a Web page, it's a much lower resolution requirement. 640x480 resolution can meet the needs of most cases, and 1024x768 image is enough to cope with late touches, cutting and other operations. Similarly, the photos you take are just stored in the computer to watch, the above resolution can meet the requirements. It should be noted that the image resolution is at least as large as the display resolution, or higher. If the image you are shooting will be placed on a projector for playback in the future, then the resolution of the selection should not be lower than the projector resolution.

　Third, the choice of stamping users:

But not all people are accustomed to just watching on the computer, or like traditional photos, then need a higher resolution. The following lists the size and minimum resolution of our commonly used flushing:

Rinse 5 inch (3.5x5) Photo: Pixel not less than 1024x768;

Rinse 6 inch (4x6) Photo: Pixel not less than 1280x960;

Rinse 12 inch (8x12) Photo: Pixel not less than 2272x1704;

The minimum resolution is listed here, and it is generally best to raise one to two grades in the lowest resolution. For life and tourism souvenir photos, the general output of the picture in 5x7 inches below, the best accuracy of 4 million pixels, that is, 2272x1704. In fact, whether the use of digital minilab or color printer output, 2 million pixels to flush out the feeling and the traditional camera is not the same, of course, this is only for ordinary users, so if the storage space is limited, the use of 3 million or 200 pixel resolution to shoot is also possible.

At the same time in many digital cameras now also provides a multi-medium image Storage format, can meet the needs of different users. More commonly used are JPEG, TIF format, RAW format and so on. JPEG image has information loss, but its storage capacity is small, quality can meet the basic needs, so the general user can choose it. And the other two formats, do not compress information, so the image quality is good, but the volume is huge, this only recommended advanced user selection. It should be noted that the image resolution and format of the selection is simultaneous, in different cases its emphasis is different. For printouts, the effect of a high-resolution, low-precision mode is better than a low-resolution, high-precision pattern. While the picture is only viewed on the computer, the effect of low-resolution high-precision mode is superior to the high resolution and low precision mode, the user can choose according to their own requirements. The choice of the image resolution in the digital camera should grasp a key, that is according to their own needs to choose. Do not blindly pursue the quality, or simply consider the number of storage, all from their own needs, in short enough to be good.