Heart of Darkness is one of the most racist and bigoted specimens of English language fiction ever written. Every African in it is depicted as a simpleton who is either servile or savage, and Africa itself is portrayed as a dark and mysterious land fit only for "civilizing" by Europeans. The late Chinua Achebe, Nigerian author of the famous
Things Fall Apart felt particular disdain for it. One of his criticism's can be found
here.
Reading the book should yield the opposite conclusion, assuming that Conrad's views are reflected by Marlow's words (and I'm not certain we should conflate the two at all times). Heart of Darkness, at one level,
is an indictment of colonialism. This comes straight from Marlow himself. In the opening pages of the book, Marlow makes the comparison between European imperialism and Roman imperialism. The only difference, he believes, is...
"...efficiency -- the devotion to efficiency... [The Romans] were no colonists; their administration was merely a squeeze, and nothing more, I suspect. They were conquerors, and for that you want only brute force -- nothing to boast of, when you have it, since your strength is just an accident arising from the weakness of others. They grabbed what they could get for the sake of what was to be got. It was just robbery with violence, aggravated murder on a great scale, and men going at it blind -- as is very proper for those who tackle a darkness. The conquest of the earth, which mostly means the taking it away from those who have a different complexion or slightly flatter noses than ourselves, is not a pretty thing when you look into it too much."
This is not the literary manifestations of an inveterate colonial sympathizer. It's true that Conrad is particularly interested in the idea of savagery, but as a universal human quality, not endemic to any one race of man. Here's a description from the book:
"Land in a swamp, march through the woods, and in some inland post feel the savagery, the utter savagery, had closed round him -- all that mysterious life of the wilderness that stirs in the forest, in the jungles, in the hearts of wild men. There's no initiation either into such mysteries. He has to live in the midst of the incomprehensible, which is also detestable. And it has a fascination, too, that goes to work upon him. The fascination of the abomination -- you know, imagine the growing regrets, the longing to escape, the powerless disgust, the surrender, the hate." Is he describing Africa? No, he's describing Britain, particularly when the Romans first arrived. Conrad is making the larger point that civilization, if not an illusion, is merely a guise for the darkness lurking in the hearts of men. I would love to engage with Achebe's entire essay, part of which I sympathize with (particularly in Conrad's use of pejorative, racist imagery) and part of which I don't, but obviously this isn't the appropriate forum to write an extended literary critique.
Anyway, to answer the original post, the image from the loading screen is a very beautifully rendered evocation, though not necessarily an outright depiction, of the famous passages in Heart of Darkness in which Marlow travels down the river on the boat. A more stylized version often graces the cover of the book: