A color version of Amazon.com Inc.'s Kindle e-reader may come eventually, but it won't be soon.

A color version of Amazon.com Inc.’s Kindle e-reader may come eventually, but it won’t be soon.

Speaking Tuesday at the online retailer’s annual shareholder meeting in Seattle, founder and CEO Jeff Bezos said that adding color to the Kindle’s “electronic ink” display is a difficult technical challenge and that a color screen is “still a long way out.” Bezos said he’s seen things “in the laboratory” that are “still not ready for prime-time production.”

Tablet computers such as Apple Inc.’s iPad and some e-readers sport LCD displays, which can show color. But those are harder to see in sunlight and consume much more power than e-ink displays.

As usual, Bezos did not detail how many Kindles Amazon has sold since the product launched in 2007, except to say customers have bought “millions” of them.

Also Tuesday, Bezos said that Amazon Web Services, which sells Web hosting and data-storage services to other companies, has the potential to be as large as Amazon’s retail business eventually. He called the overall market for such services a “very, very large area” that is generally not being done efficiently.

“Whenever something is done inefficiently, that creates an opportunity,” Bezos said.

For now Amazon’s Web services division has a long way to go. It is part of a group that had $188 million in revenue in the first quarter, while Amazon’s retail operations brought in nearly $7 billion.