Kiteretsu Daihyakka was a manga series by popular manga author Fujiko F Fujio (notable for Doraemon) that ran in the children's magazine Kodomo no Hikari from April 1974 to July 2000. It also had an anime adaption which ran from March 27, 1988 to June 9th, 1996. The anime is still popular today because it has been broadcast worldwide in India by Disney-owned Hungama TV, a few Spanish/Latin American television channels under the name of Kiteretsu: Nobita's Clever Cousin (linking to the Doraemon series) and Cartoon Network Korea.
The first manga tankobōn.
An screenshot has circulated online of a possible pilot. The image features Kiteretsu with Miyoko on a flying machine (possibly an early anime-exclusive design for Kiteretsu's own time machine), with Korosuke (Kiteretsu's robot) next to them. It is unknown if it could be a concept image or a cel for a possible pilot. Although the series already has an hour-long pilot, it is possible that this image could be an unaired, possibly never finished pilot. The image looks more original to the manga: Korosuke still has his pink face - yet in the anime his face is yellow. Kiteretsu and Miyoko are also wearing costumes that were never seen in the final product. It is likely that Motoo Abiko (AKA Fujiko Fujio A), who made two series with F (Obake no Q-tarō and Magic Sahara) could know something about this mysterious photo. In the meantime, nothing is known about the image; although a few Japanese sources have it. If the pilot does exist then it is not likely that it will ever see the light of day but it is more likely that it is just fans of the series jumping to conclusions about a lost episode.