Every raga has an individuality derived through its particular pattern of ascending and descending notes and, more importantly, the manner in which they are rendered. Individual characteristics of a Carnatic raga depend more on the ornamental relationships of notes and phrases than on the interrelationship of notes based on principles of consonance, assonance and the like (as against systems like Western or Hindustani classical).
Key factors that determine the image of a raga are
Plain and oscillated notes : There are very well-defined rules as to which notes can and cannot be oscillated in a given raga. A common illustration of this can be seen in Shankarabharanam, where the note Ga can never be oscillated (while Ri, Ma, Da and Ni allow oscillation), while the raga Kalyani allows oscillation on Ga.
Long and Short Notes : Just by the amount of time an artiste dwells on a note, a raga can be made or marred. For instance, the raga Surutiwould never allow more than a fleeting glance at Ni and Ga, while Kedaragowla would be incomplete if those notes were not sustained longer.
Place Value of Notes : A few notes may be sharpened (rendered slightly higher than their value) or flattenedX rendered slightly lower than their value) depending on the context, which makes Carnatic music a place value-based system rather than face value-based. A case in point is the higher-than-normal value of Ni in certain ragas like Shankarabharanam, Kalyani and Hamsadhwani, especially in ascending phrases, and the lower-than-usual value of Ri in ragas such as Saveri.
Starting, Ending and Developing Points: It is not possible to start or end phrases with any note in any raga. For instance, one may find it absurd to sing a phrase like D M G R^S in Reetigowla even though none of the notes are theoretically incorrect. Similarly, one will not find Da an apt point for developing a raga like Anandabbairavi.
Key Phrases : Besides all these, there are certain life-giving, characteristic phrases without which a ragas image can never be fully brought out. These characteristics can be better appreciated by listening to the works of great composers and to high-quality artistes.