A holo-image was a type of Talaxian holotechnology similar to photography. If not properly maintained, they could fade over time.

Neelix lost his entire family to the metreon cascade. When Neelix was delivering "a treasure trove" of Hansen field logs to Seven of Nine, he lamented that all he had left of his family was a faded holo-image of his sister Alixia. (VOY: "Dark Frontier")