Django and SimpleUploadedFile

My form contains imagefield but the values of this form are recuperated by a method ajax...

The probleme is when ajax recuperated value of imagefield, this value is just a name of the image and not imagefield, So I can't save the image entered by user in my form...

How can I do ?

I make this, my method ajax send to my view the name of image ("tree.jpeg") entered by user. I try this in my view :

    from django.core.files.uploadedfile import SimpleUploadedFile
        file_contents = SimpleUploadedFile("%s" %(imagename), request.body)
        llog = ModelContainsImageField()
        llog.image.save(imagename, file_contents, True)
        llog.save()
        projet.log = llog

It don't works :/