Unfortunately, we are unlikely ever to see any of Delecroix’s paintings as they were intended to be seen. Fading pigments and other factors make this true for every painting, but doubly true for Delecroix as he used a lot of new pigments that were very unstable.
There is the story of Degas standing weeping with sadness in front of The death of sardenopolis at the way its colors had faded over time.