Resolution how much do you know?


In this digital age, the popularity of digital cameras is getting higher and higher, and resolution has become a topic of great concern to people.But how much do you know about resolution?Below I will give you a comprehensive analysis of the resolution.

When we buy a digital camera, resolution is a very important indicator.In the early years, the resolution of digital cameras was very low, such as CASIOs QV-10 less than 100,000 pixels (320X240), 180,000 pixels KODAK DC20 (493X373), its resolution is not comparable to the current camera phones and cameras.After nearly ten years of development, the resolution of digital cameras continues to increase, and now has more than 10 million pixels.

Taking 2048X1536X16M, 2048X1536 means that there are 2048 pixels in the width direction and 1536 pixels in the height direction.2048X1536 = 3145728, we call it 3 million pixels.The latter 16M refers to the color depth.

Each pixel is colored, and the color of each pixel is recorded with 3 BYTEs, which are red, green, and blue, respectively.Each BYTE can record 256 levels, so a total of 256X256X256 = 16777216 different colors, namely 16M, also known as 24-bit color depth.Therefore, if an 2048X1536 pixel image file is recorded in RGB colors, 2048X1536X3 = 9437184 BYTEs, which is 9MB, plus other information such as the file header, will eventually be greater than 9MB.Resolution, how much do you know? td

However, most digital cameras usually use JPG format, which is a distorted, relatively compressed image file format. In general, 2048X1536 pixel JPG files have different file sizes according to their compression ratios, about 1-2MBabout.The file size of other pixels such as 1600X1200X16M can also be calculated.

It can be seen that the number of pixels included in the photos of 2048X1536X16M and 1600X1200X16M is different, that is to say, the information content is different.If you print photos with the same output resolution, the size of the resulting photos will be different. Conversely, if you output photos of the same size, the number of pixels in the unit length of the photos will be different.Different.Lens resolution In addition to the pixel resolution of digital cameras, the resolution of the lens is also an important indicator.

Resolution is an important indicator for judging the quality of a lens. It is generally expressed by the number of line pairs that can be distinguished in a unit distance (such as the number of line pairs per millimeter lp / mm).The resolution of the lens determines to a certain extent the clarity of the subject after imaging through the lens. When it comes to resolution, we must first figure out what can be distinguished and what cannot be distinguished.

There is a standard in optics called the Rayleigh criterion.We know that there are aberrations in any lens. A point on an object is not a point after imaging through the lens, but a distribution, also known as a diffuse garden.If two points on the object that are close to each other are originally resolvable, it may become indistinguishable after imaging.This caused the image to be blurred. According to the Rayleigh criterion, if the light intensity between two points does not exceed the maximum light intensity of 81.1%, we can feel there is a dark area between these two points, these two points can be distinguished.

Otherwise, the two points will be connected, and we cannot distinguish whether this is two points or one point.This is indistinguishable.Therefore, we say that the Rayleigh criterion is the basis for determining resolution.Although this criterion is actually based on experience rather than theory, it is generally recognized in optics. Obviously, the aberration size of the lens determines that the good lens aberration of the large campus of the dispersion garden is smaller, the resolution is higher, and conversely the resolution is lower.In addition, it must be pointed out that even in the ideal case without aberrations, due to the existence of the phenomenon of light diffraction, the image formed by a point on the object is also a diffuse spot, which is called the Airy spot at this time.The size of the Airy disk is related to the wavelength of light and the aperture of the light.Can be theoretically introduced, resolution, how much do you know? The diameter of td Airy spot is 1.22λ / d, where λ is the wavelength of light and d is the diameter of the clear aperture.This is why the maximum aperture is an important performance indicator for camera lenses.

In some specific occasions, when the resolution is very high, the effect of Airbend s resolution cannot be ignored.For example, in the submicron large-scale integrated circuit platemaking lithography process, the exposure wavelength used is getting shorter and shorter for this reason. Printers and digital printing From the discussion above, we can see that the resolution of a digital camera is not the real resolution, but the number of pixels.This resolution is not directly related to the quality of the printed or digitally printed photos.It is the output resolution of the printer or digital processing device that determines the quality of the photo. The resolution of the printer refers to the maximum number of dots per inch that can be printed per inch in the horizontal and vertical directions when printing out.

The resolution of print output devices such as digital printing is called ppi (pixel per inch), which means the number of pixels per inch.The higher the resolution of the printout, the smaller the size of the dots produced, and the finer the printed image. At the same time, we should note that when the image file with the same pixel number is printed out, the higher the resolution, the smaller the output image.If it is also a 2560X1920 pixel image file, print it with a resolution of 300ppi, you can get a 8.5X6.4 inches (that is, 10 inches) photos, and with a resolution of 150ppi, you can get 15X12.8-inch (ie 20-inch) photos. If photos with three resolutions of 2048X1536X16M, 1600X1200X16M, and 1024X768X16M are also digitally processed into 5-inch photos, how much will the effect be different? To answer this question, we must first consider the resolution of the digital output device.The length and width of a 5-inch photo are 5 and 3.5 inches.If you use the highest resolution of Fuji Frontier printing equipment (about 300ppi) to output.The pixels required for a 5-inch photo are 1500X1050.In other words, the effect of the 2048X1536X16M and 1600X1200X16M photos is completely indistinguishable.Even if you use 1024X768 photos to print, the effect is also limited.If you use a resolution of 150ppi (which is an acceptable resolution under general requirements) to output, the photo processing effect of the above three resolutions will be no different.

We can say that high resolution is only meaningful when developing large-size photos.If you only develop smaller photos such as 5-inch and 6-inch, large-resolution photos cant show the advantage. Here, by the way, simply say that ppi and dpi are the differences between the two concepts.Ppi is about image details, which refers to how many pixels per inch, and dpi is the physical capacity of the output device, for printers is how many dots per inch.Green peppers and red dragons will all develop color. Now general laser printers can have a print resolution of 600dpi.However, the dots printed by the printer have no gray scale, which means that there are only two cases of black (a bit) and white (no dots).When printing text or black-and-white binary images like line graphics, there is no problem.When printing grayscale photo images, it is different.

At this time, the dithering algorithm is generally used to replace grayscale with density.In this case, a gray-scale "pixel" should be represented by a combination of many gray-scale "dots".In this combination, the more black dots, the darker the pixel, and the closer to black, otherwise, the lighter the color.Therefore, although the dpi of the printer is high, the ppi when printing the image is actually much smaller. Scanner resolution Lets talk about the resolution of the scanner.In the evaluation of scan quality, the resolution of the scanner is a very important factor. Resolution refers to the amount or density of information obtained when digitizing.The resolution of the scanner is also divided into optical resolution and interpolation resolution. As an indicator of the scanner, the optical resolution refers to the highest information density (that is, the number of pixels obtained per unit length) that can be scanned and sampled by the optical system of the scanner; the interpolation resolution is the resolution obtained after interpolation calculation.Obviously, the most important thing to evaluate the resolution of a scanner is its optical resolution (just like the optical zoom factor of a DC lens is the most important, digital zoom is just a pseudo zoom).

When scanning, the specific scanning resolution can be set.The amount of information obtained with high-resolution scanning is large, and the resulting file size is also large.Therefore, it is not the higher the scan resolution, the better. Generally, the scan resolution should be set according to the needs of future printouts.Now that the resolution is mentioned, lets talk about the resolution of the monitor by the way. If 2048X1536X16M, 1600X1200X16M, and 1024X768X16M are also displayed in 1024X768 (display resolution), will there be any difference? When it comes to this issue, you have to talk about the resolution of the monitor.Like a digital camera, what we mean by display resolution is not resolution in the physical sense, but pixels, which refers to the number of basic pixels that can be displayed on the screen.With the development of display technology, the resolution of the display is getting higher and higher.From the early years of CGA (320X200) to EGA (640X400), VGA (640X480) to the currently commonly used 1024X768.The images and characters displayed on the monitor are getting more and more refined, and the quality is getting higher and higher. If you want to say the resolution in the true sense, it is not only related to the display mode, but also related to the size of the display.In the case of 1024X768, if it is a 15-inch display, its diagonal inches.The resolution should be around 85 dots per inch.For a 20-inch display, the resolution is 64 dots per inch.When the screen size is large, the resolution is small?

This is not surprising, because the screen size is larger, you can support more pixel modes.If the screen size is 20 inches, you can have 1600X1200 or 1920X1440. On a 1024X768 resolution monitor, 1024X768 photos can be seen in full size when displayed at 100%, while 2048X1536X16M and 1600X1200X16M resolution photos cannot be seen in full size when displayed at 100%.You can display it as a small percentage (such as 50%).Or use 100% to display, but at this time you can only see a part, and use the method of moving the photo up, down, left, and right to see the other parts. How about, through the above introduction, have you got a better understanding of resolution?In this way, when you buy related digital products, you can be confident :)

Resolution how much do you know? AROWANA ForumThe best water temperature for raising red dragon:What fish tank is used to raise red dragon^What is the cost of keeping arowana for one year"Is it better to raise a golden dragon or a red dragon?%Raising a red dragon through a tank, okay?$Raising red dragon on white background%Why can"t you raise a red dragon through the tank#Is the half-dragon fish good to keep@Can a 90-long tank keep arowanaCan the tank of 80 keep arowana~

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