WASHINGTON - Mitt Romney emerged from the Republican convention with an overall improvement in his image among voters but no significant change in the number who say they will vote for him, according to a Reuters/Ipsos poll released on Friday.Republicans nominated Romney on Thursday after three days of testimonials from friends, relatives and supporters, many aimed at showing the candidate in a more informal light. Romney has struggled to shake off perceptions of being stiff and aloof. The four-day rolling poll has Democratic President Barack Obama still leading Romney in general favorability, 52 percent to 50 percent.But the poll showed Romney steadily improving in likeability and other positive-image features.Thirty-one percent of the registered voters responding to the survey found Romney "likeable" in Friday's poll, up from Monday's 26 percent. Obama enjoys a 48 percent likeability rating."The Republicans had the task at the convention of making their candidate more palatable, likeable to the American electorate," said Ipsos pollster Julia Clark. "Our data suggests they have absolutely succeeded."Especially notable was Romney's boost among independents, 45 percent of whom rated him favorably, compared with Thursday's 34 percent. Twenty percent of independents found him likeable, up from Thursday's 16 percent.Nearly two out of five of those surveyed also found Romney, "tough enough for the job," outpacing Obama among all registered voters and among independents specifically.Although lagging behind Obama in most other favorable metrics, Romney continued to make headway in categories such as "represents America," "understands people like me" and "is a good person."Respondents said Romney would be more effective than Obama as president by a margin of 37 percent to 33 percent. The margin was even wider among independents, at 26 percent versus 17 percent.Romney and Obama remain in a dead heat in most national polls of voting intentions. Friday's Reuters/Ipsos poll had Romney with a slim one-point lead among likely voters, effectively unchanged from the day before.But Clark said such voting intention polls may be less relevant than concerns about a candidate's image, especially among independent voters and others on the fence, as the race is likely to remain close all the way to the Nov. 6 election."It was more important for Romney to create a more positive image," she said. "Some of these softer metrics, image issues, they contribute to factors like trust that ultimately do sway some people" when time comes to vote.For the survey, a sample of 1,632 registered voters was interviewed online. The precision of the Reuters/Ipsos online polls is measured using a credibility interval. In this case, the poll has a credibility interval of plus or minus 2.8 percentage points.