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Chroma key was extensively used for digital set extensions , backgrounds , or scenes that required cinematographer David Tattersall to seek powerful lamps to light the sets and visual effects supervisor John Knoll to develop software that would remove the blue reflection from shiny floors .
 David Tattersall, John Knoll
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: media, plant, vehicle, astronomical object, time, disease, animal, location, person, organization, mythical figure, food, biology, geographical phenomenon, instrument, event 
Text: {0} 
Answer:
 David Tattersall, John Knoll