What type of images are they, and how are you loading them?
Also, what do you mean when you much much darker? Do all the colors appear as their darker variant, or is it some parts of the image that appear black or some dark colour? If it’s the former, then the issue is probably with the loading of the image, the data in it not being interpreted the right way.
It would also be useful if you’re able to share any of the images, along with how they look in Julia vs other image viewers.