The concept of resolution is present in different areas, and in addition to the one related to photo processing, it is used in geography, mathematics, and logic, as well as in the area of law and in other fields.
Regarding the definition of this term in terms of photography, it is primarily used to define clarity, that is, the sharpness of an image. It also applies when it is necessary to describe the properties of a particular printer or monitor, and when defining raster, i.e. raster graphics.
Generally speaking, resolution is the basic measure of the sharpness of an image and is defined as the number of pixels on the screen, or as the number of points produced by a particular printer. And when it is known how big exactly the resolution is, then it is certainly known to what extent a certain image is sharp, i.e. clear.
When it comes to video graphics resolution, it is measured both vertically and horizontally, and there are several types of resolution, primarily referring to the image resolution, screen resolution, but also resolution of a specific printer, and there is also term optical resolution as well as spectral resolution.
Screen resolution is defined when it is necessary to determine how clearly a particular text or image is displayed on the screen. And it is quite logical that both text and image are clearer if the resolution is higher, and if the resolution is smaller it can significantly affect the deterioration of the quality of a particular image or text. Anyone who uses a particular computer has the ability to adjust, that is, to change its resolution, and if it happens that the resolution not supported by a particular screen is set, it will then turn black for a few seconds and the monitor's settings will automatically be readjusted to the basic resolution. In order to precisely define the resolution of an image, the so-called spatial resolution, which is also known as the angular resolution, is especially important. It is defined as the ability of a particular device (camera, microscope, optical telescope, etc.) to form a particular image or to pay attention to fine details within a particular object. When we talk about the so-called resolving power of a particular device, then we actually mean that it is able to separate extremely precisely the specific points of a particular object when they are located at a relatively small angular distance. However, this is primarily related to describing the resolving power when using telescopes or microscopes.
There is also a so-called video resolution, and it is actually defined as the ability of a certain device's screen, such as a computer or TV monitor, to display an image with the application of individual pixels. Then the particular image is displayed in two dimensions, so it shows what the horizontal and what exactly the vertical resolution is, that is, how many separate points or pixels are located within a single image on a horizontal and vertical basis. Although many think so, the fact is that image quality cannot be solely determined by resolution; there are many other data that have a direct impact on the improvement or deterioration of the quality of a particular image.
In addition to all of these, there is also so-called 4k resolution, which is directly determined by the Digital Cinema Initiatives - DCI. In general, it is a standardized pixel ratio, which in this case implies 4 096 x 2 560 pixels.