The context of this paper is agricultural remote sensing imagery. Its objective is to propose a blind framework for the partial unmixing of multi or hyperspectral images. This framework relies on a linear mixing model with physical constraints related to the positivity and the dependence of the mixing coefficients. It hinges on three steps. The first step is a non-constrained source separation operation using Independent Component Analysis. Then, a vine-related source is selected by comparing the various sources to a rough vegetation index map. Finally, a fuzzy clustering algorithm is applied to the vine-like source to provide a soft classification of pixels into vine and non-vine pixels, i.e. a vine abundance map. The entire framework is successfully applied to hyperspectral CASI data acquired on vineyards. Results are provided which allows discussing the relevance and the capabilities of the approach.