Illustration of the proposed method with K source domains and a target domain. Each source domain XSi and the target domain XT include samples from two categories (marked as triangles and circles). The first strategy of the proposed method is to transform each source domain and target domain into a latent representation domain via the specific projection Pi and the common projection P (with Pi = P + EPi, EPi is the sparse error term), respectively. Based on the transformed target domain data PXT, the second strategy is to linearly represent each sample from each source domain using all samples from the target domain in the latent space (e.g., PiXSi = PXTZSi + ESi). Dotted arrows represent the first strategy, while the solid arrow represents the second strategy.