DPI represents the resolution, refers to the number of points on each inches. DPI can be subdivided into horizontal resolution and vertical resolution, such as a 1 inch * 1 inch picture, if its horizontal resolution is 100 DPI, vertical resolution The rate is 50 dpi, then, it is divided into 100 small sections per inchere, and vertical is divided into 50 small sections per inch, just like a grade on the rice. This picture has a total of 100 * 50 = 5000 lattice, this picture There are 5,000 pixels. Since its horizontal resolution and vertical resolution are not equal, each pixel is a tiny rectangle.
Therefore, the pixels are actually a concept of an area, and because the pictures produced by the general computer / digital camera, the pictures produced are horizontal resolution and vertical resolution, each pixel is a tiny square, so it is "DPI to represent each inch. The number of pixels on the length "is actually" the number of points per inch length ".
The size of each pixel is determined by the production process. The higher the process, the smaller the area of each pixel, and the more pixels can be accommodated on each square inch screen. The higher the DPI value, the finer image is fine, the pixels are small to people The eye is distinguished, and the image looks with the actual difference.
The concept of "how many thousand pixels" of digital cameras is this, for example, a camera can take up to 1600 pixels * 1200 pixels, its pixel value is 1600 * 1200 = 1.92 million, about 2 million, This is a 2 megapixel digital camera.
The 300 DPI mentioned in the problem has 300 points on the horizontal and vertical direction of the screen. The actual height of this machine is used to combine the number of pixels and DPIs. For This machine, 400 pixels is 400/300 = 1.33 inches, 533 pixels are 533/300 = 1.78 inches.
For a computer photo, you can change its resolution in Photoshop's "Image" menu, the default is 72, the change is the narrowing picture, changed, it is zoomed (loss of image quality ), In fact, it is an effect of zooming in narrowing. To tell the truly impact, it is the impact of some image printouts that require high resolution. You can open the "File" - Print Options menu to view print previews.
(With: 1 inch inch = 25.4 MillimetRes mm)
