The new G3 phone stands out in having a high-resolution display that has 538 pixels per inch. Other leading phones are in the 300-pixel range, with a handful reaching the 400s. The G3's display measures 5.5 inches diagonally.
The G3 also promises fast auto-focusing on its 13-megapixel camera and the ability to unlock phones not with passcodes but a pattern of taps on the screen. It also promises a keyboard that is easier to type on.
LG said the phone will be available in the U.S. this summer through all major wireless carriers. Prices weren't announced at the Tuesday event.
Many of the innovations in the G3 are familiar. For instance, it offers a way to protect certain content when lending a phone to others. Samsung's new Galaxy S5 phone has a similar feature.
The South Korean company has had trouble getting noticed for its smartphones in a market dominated by Samsung Electronics Co. and Apple Inc.
Last year's G2 phone was notable for moving the power and volume controls to the back, which the company said made the phone easier to handle and less prone to drops. But the phone got little attention. The G Flex, a phone with a curved display, was expensive, and the benefits of the slight curve weren't apparent. LG also makes the Nexus 5 phone under Google's brand.
According to Gartner, LG had a market share of less than 5 percent last year, in fourth place just behind Huawei. Samsung had a 31 percent market share last year and Apple had 16 percent.