if (document.images) {

empresaon = new Image();    empresaon.src = "empresa_2.jpg";
empresaoff = new Image();    empresaoff.src = "empresa_1.jpg";

servicoson = new Image();    servicoson.src = "servicos_2.jpg";
servicosoff = new Image();    servicosoff.src = "servicos_1.jpg";

tecnologiaon = new Image();    tecnologiaon.src = "tecnologia_2.jpg";
tecnologiaoff = new Image();    tecnologiaoff.src = "tecnologia_1.jpg";

atuacaoon = new Image();    atuacaoon.src = "atuacao_2.jpg";
atuacaooff = new Image();    atuacaooff.src = "atuacao_1.jpg";

rastreamentoon = new Image();    rastreamentoon.src = "rastreamento_2.jpg";
rastreamentooff = new Image();    rastreamentooff.src = "rastreamento_1.jpg";

anvisaon = new Image();    anvisaon.src = "anvisa_2.jpg";
anvisaoff = new Image();    anvisaoff.src = "anvisa_1.jpg";

}

function imgOn(imgName)
{if (document.images) {document[imgName].src = eval(imgName + "on.src");}}

function imgOff(imgName)
{if (document.images) {document[imgName].src = eval(imgName + "off.src");}}