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Direct imaging is a method of discovering and observing extra-solar planets, but can be done only for nearby stars, planets orbiting far from their stars (e.g., many AU), and hot (bright) planets and/or cool stars, such as brown dwarfs. It is merely imaging the planet, but generally requires specialized methods to avoid the glare of the star, such as use of a coronagraph. Planets have been observed and sometimes discovered using this technique, for example, those around HR 8799. Such observation is considered necessary for spotting some types of biosignatures, likely for any that are part of the planetshine.
Coronagraphs were conceived to observe at the Sun's corona, and the direct imaging of planets presents somewhat different challenges: light must be blocked from a much smaller region of the sky, and the planet may be at an extremely small angular distance from its host star, and because planets are relatively dim, very high light sensitivity is needed to discern them from the background light and noise: ADI and RDI are among the techniques. Schemes to use a starshade (spacecraft serving as an occulter) for direct imaging in space have been proposed.
The phrase direct imaging is also commonly used for other challenging-to-image objects such as protoplanetary disks.