I've added Schema.org on my blog list with JSON-LD:
{
    "@context": "http://schema.org",
    "@type": "BlogPosting",
    "headline": "Fixer la navigation Off-Canvas sur Foundation",
    "image": "https://stephane-richin.s3-eu-central-1.amazonaws.com/S/foundation-website.jpg",
    "author": "Stéphane Richin",
    "datePublished": "2015-02-03",
    "dateModified": "2015-02-03",
    "publisher": {
        "@type": "Organization",
        "name": "Stéphane Richin",
        "url": "http://stephane-richin.fr",
        "logo" : "http://stephane-richin.fr/images/logo/logo-stephane-richin.svg"
    },
    "mainEntityOfPage": "True"
}
But, I've 2 warnings on image and logo:
image.itemtype has wrong value
logo.itemtype has wrong value
Do you have any idea why image and logo have wrong values?