Image processing Fundamentals pixel high-width resolution

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Several basic concepts and their relationships in image processing:

Pixel: An information point that stores an RGB color value is called a pixel. The unit is PX.

Resolution: Indicates how many pixels of a physical unit an inch, in px/inches or px/centimeters. we all know that the higher the resolution, the clearer the image, the finer the texture, and the lower the resolution, the more blurred the image, the coarser the texture.

With these two concepts, the relationship between the size of the image and the resolution Pixel is illustrated.

First of all, the computer is how to store the image information, for the bitmap, the computer is stored in the picture information point color value and information point location, bitmap image is to rely on a matrix to store the image, can be imagined as a two-bit array, the subscript is the pixel in the picture in the coordinates of the location, The RGB color value of the pixel is stored in the array element.

So we're going to describe a picture of a physical meaning (attention is physical)? If a person who does not know computer knowledge can describe a photograph, he must only describe it this way: it is a picture of how many inches, how many inch, how many inches wide. Indeed, this is the only way to describe the size of a picture, if not from the point of view of the computer's storage. So the question is, if we have a long and wide picture of an inch, how do we put this picture into a computer to store and show it?

We know that the computer is stored in 0 and 1, so you want to put a physical picture into the computer, the key is how to put a physical picture to the computer storage way to describe it, the description of the method has 2, one is a bitmap description, a proper description of the figure, bitmap description is what we said above the matrix, A matrix similar to a two-dimensional array to represent a matrix of pixels, each matrix element is stored in the RGB color values, then the question is, how much need a matrix to describe a 1-inch square picture? This does not require, if your matrix is larger, such as I use a a[2000][2000] array to store the pixel RGB color value, then the more information you store, the more detailed the picture description, the corresponding picture in the computer to reflect the larger the size (such as 2M); If your matrix is smaller, such as using a[200][200] to describe a picture, the more coarse the picture is, the smaller the volume stored in the computer. Such a saying, may be enlightened, this is not the concept of resolution?

Yes, the resolution is the principle, such as we have a picture, long and wide physical dimensions are 1 inches, in the computer storage is 72 pixels per inch of the resolution to store, then this picture in the computer there is a total of 72x72 pixels to be represented, that is, the image resolution is 72 pixels/ Inches. If it is stored in 144 pixels per inch, then in the computer needs 144x144 pixel matrix to represent, this time the image resolution is 144 pixels/inch, the same physical size, the higher the resolution, the more delicate the picture, the larger the storage volume.

In combination with the resolution of the image above, we let us distinguish the resolution of the screen, we know that a screen is used to display the image, then the screen resolution refers to the size of an inch of the physical screen contains the number of pixels, such as we have a picture stored in the computer, the resolution is 72 pixels per inch, The physical size of the picture is 1 inches. We also have a block resolution set to 144 pixels per inch of the display, then this picture with this display, the actual physical length and width of how much? We can calculate:

Because it is a square picture, we only discuss his width, 1 inches x72 pixels per inch = 72 pixels, which means that this picture is stored in the computer is a 72x72 pixel matrix, the width of the direction contains 72 pixels. Our screen is a 1-inch physical screen containing 144 pixels, so our picture on this display actually shows the physical size is 0.5 inches. Well, if we set the screen resolution A little higher, the image will appear smaller at its own resolution, and if the screen resolution is lower, the image will open up, which is the relationship between the screen resolution and the image resolution. It is not difficult to find the following formula:

Picture long (wide) physical size × picture Resolution = picture Length (width) pixel count = screen Current Resolution x the length (width) of the physical size of the image displayed on the screen.

Understand this principle, we use some image processing software such as PS or in the programming can be done at ease, handy.

Image processing Fundamentals pixel high-width resolution