Caffe convert_imageset with one class/ label

Question

I want to create an lmdb dataset from images which part of them contain the feature I want caffe to learn, and part of them don't.
My question is - in the text input file transferred to convert_imageset - how should I label those images that don't contain the feature?
I know the format is

PATH_TO_IMAGE LABEL
PATH_TO_IMAGE LABEL
PATH_TO_IMAGE LABEL

But which label should I assign to images without the feature?
For example, img1.jpg contain the feature, img2.jpg and img3.jpg don't. So should the text file look like -

img1.jpg 0
img2.jpg 1?
img3.jpg 1?

Thanks!

Answer 1

Got an answer from Caffe-users Google Group - yes, creating a dummy feature is the right way for this.
So it is:

img1.jpg 0
img2.jpg 1
img3.jpg 1