Sign
Augustine argues that a sign “is a thing which causes us to think of something beyond the impression the thing itself makes upon the senses” (Hellbrunn, 1997, p. 176) and Peirce states that a sign is “an association between a representation, an object and an interpretant” (p.180) For Peirce, a sign is a thing that “stands to somebody for something in some respect or capacity” (Lury, 2004, p.76), it is a communicative act which “enfolds” the real or “implies it”. Thus, a sign must be visible and objective that motivate the people’s mental activities such as memory, knowledge, etc.
Icon
McCloud defines icon as “an image used to present a person, place, thing or idea” (McCloud, 1993, p.24). For instance, two dots, one line with a circle around them constitutes an icon of a face. Icons are signs which refer to the objects that are imitated by them. It directly makes people associate the objects that it imitates. There are icons of language, science and communication and there are icons of the practical realm. Icons can be either graphical or non-pictorial. In the non-pictorial icons, meaning is fixed and absolute. Their appearance does not affect their meaning because they represent invisible ideas. In pictures, meaning is fluid and variable according to appearance.
Symbol
McCloud thinks that symbols are one category of icon (McCloud, 1993). A symbol is an object that can be seen as an indication of a metal activity, an idea, an objective entities or phenomena. A symbol always has a meaning that is hidden behind it, and the meaning can be subjected to different interpretations or explanation. Peirce defines symbol as “a sign which refers to the object that it denotes by virtue of law, usually an association of general ideas, which operates to cause the symbol to be interpreted as referring to that object” (Lury, 2004, p.78)
Image
Images are visual representation of certain objects or certain scenes. An image can be either graphical or alphanumerical. Peirce regards image as a “mobile material, as universal variation, the identity of matter with movement and light” (Lury, 2004, p,75) and he thinks that the image is a set of logical relations which is always in continual transformation between the signifier and the signified. In media culture, image can be considered as a view or an idea that the people has towards a product or a brand. It is about the impression of a product or a brand that people have in mind.
Logo
According to Heilbrunn, the logo is a “sign which is commonly used to represent different entities such as organizations, companies, brands, countries, etc” (Heilbrunn, 1997, p. 175), “a moving and evolutive structure of identifying elements” (p.187). Generally, there are three types of logos: the logotype, the icotype, and the mixed logo and the representative power of the logo is linked to legitimacy and analogy. The logo has a semiotic function, a “warrior” function and a “reproduction function”. It has its meaning by referring to the internal dependencies between the ingredients of the logo and the external system of signification constituted by other logos.
Even though the icon is a kind of sign, it can be distinguished from a sign for it can only be made of a real image while a sign may not have a physical appearance. For example, the icon of the Android system is a real image of a robot while the opening music of a Samsung phone as a sign of its products is not an objective subject. Through an icon, people can directly discern what it refers to, while a symbol often indirectly reminds the people of an object by educating them about the connection between the symbol and the objects. For instance, when we see an icon of a smiling face, we know that it stands for a smile. However, when we see five colorful rings connected together, we can only recognize that it is a symbol of Olympic Games on the basis of our previous knowledge of the relation between the connected rings and Olympics. Icons and logos are images, but they are not random images. Instead, they are images that has connotation which can be related to an organization, a company or a brand. Signs and symbols can also be images but need not to be so. Although a logo can make use of an icon, an icon can only present the objects it resembles while a logo must have reference to an association or group. Under most conditions, a logo can be a sign or a symbol of an organization or a brand, but other things such a slogan, a sound or an advertisement can also be a sign or a symbol of an organization or company.
References
McCloud, S. (1993). Understanding Comics. The Invisible Art. New York: Harper Collins.
Heilbrunn, B. (1997). Representation and legitimacy: A semiotic approach to the logo. In W. Nöth (Ed.), Semiotics of the media: State of the art, projects, and perspectives. Berlin: Mouton de Gruyter.
Lury, C. (2004). Brands. The Logos of the Global Economy. Abingdon / New York:Routledge.