Rupert Howell, managing director, ITV brand and commercial, said there was "more potential for" ITV3 and ITV4, as they are less defined than ITV1 and ITV2.
ITV would not confirm any timescale for changes to its channels. However, Howell said ITV wanted to be "more precise" with the two older-skewing digital channels, ITV3 and ITV4.
"It is a balancing act, although they are doing so well that we don't want to spoil that," he said.
In May, ITV3 had a 1.5% share of total TV viewing, compared to 1.3% a year ago, while ITV4 has a 0.9% share, up from 0.6% a year ago.
The top-performing programmes on ITV3 are currently Midsomer Murders, Primeval and Poirot, while ITV4 airs films, motor sport such as the Isle of Man TT, and football highlights.
Howell said that both channels are "vaguer" than ITV2, which has driven up younger audiences with programming including America's Got Talent, Supernatural and Katie & Peter.
Howell said new director of television Peter Fincham would be keen to look for opportunities for programmes on its digital channels "which can move on to ITV1".
Phil Hall, TV director at agency MediaCom, said: "It can't ever hurt in terms of improving identities of channels. ITV4 would benefit more."
He added: "People choose a group of channels and stick to them, so the important thing is to make them ‘go-to' channels. But it is obvious what each of the channels does now - they are quite good from a buyer's point of view."
.jpg)
.jpg)