What are “full duplex” and “half duplex”
Full-duplex: can send and receive at the same time. Full-duplex requirements: There are separate channels for receiving and sending, which can be used to realize communication between two stations, star network, ring network, and cannot be used for bus network.
Half-duplex: It is impossible to send and receive at the same time, and the sending and receiving are time-divisional. Half-duplex requirements: transceivers can share the same channel, and can be used in local area networks of various topologies, most commonly used in bus networks. The half-duplex data rate is theoretically half of full-duplex.
What are “brightness”, “hue” and “saturation”
As long as color can be described by brightness, hue and saturation, any colored light seen by the human eye is the combined effect of these three characteristics. So what do brightness, hue, and saturation mean?
Brightness: It is the feeling of brightness caused by light acting on the human eye, which is related to the luminous intensity of the observed object.
Hue: It is the color feeling produced when the human eye sees light of one or more wavelengths. It reflects the class of color and is the basic characteristic that determines color. For example, red and brown refer to hue.
Saturation: refers to the purity of the color, that is, the degree to which white light is incorporated, or the depth of the color
For colored light of the same hue, the darker the saturation, the more vivid or pure the color. Hue and saturation are commonly referred to as chroma.
It can be seen that luminance is used to indicate the brightness of a certain color light, while chromaticity indicates the type and depth of color. In addition, the various colors of light commonly found in nature can be made by matching red (R), green (G), and blue (B) colors in different proportions; similarly, the vast majority of color light can also be decomposed into three colors of red, green and blue, which forms the most basic principle in chromaticity, the principle of three primary colors (RGB).
Search for pictures by picture
Search for pictures by picture has become the basic function of intelligent video surveillance system. Search by image is a professional search engine system that provides users with relevant graphic image data retrieval services in the video surveillance system or on the Internet by searching for image text or visual features. It is a subdivision of search engines. Search by entering keywords that are similar to the image name or content, and search by uploading images or image URLs that are similar to the search results.
Broadly speaking, image features include text-based features (such as keywords, annotations, etc.) and visual features (such as color, logo, texture, shape, etc.). Visual features can be further divided into general visual features and domain-related (locally specific) visual features. The former is used to describe the features common to all images, regardless of the specific type or inner core of the image, mainly including color, texture and shape; the latter is based on some prior knowledge (or assumptions) about the content of the described image, and is closely related to specific applications, such as human facial features or vehicle license plates or vehicle characteristics.
Searching for images by image has been used as a basic function of the A application. By providing a global or local feature, such as a photo of a vehicle, a license plate, a face, a body feature, etc., the user can quickly perform surveillance retrieval from the video image information database.