The technique is particularly important to structural inputs such as images (natural or hyper-spectral), since the convolution operator is shift-invariant and does not break the spatial configurations. This part of the thesis is particularly dedicated to exploring online methods for efficient CDL algorithms where input signals are provided in a streaming fashion to update the dictionary, because the batch mode CDL is time and memory-consuming in nature.The methodology adopted in this part is a systematic extension of classical unsupervised online sparse coding algorithms to the convolutional sparse coding domain, with efficient optimizations achieved via a localized "slice-based" representation of sparse features. Specifically, a slice-based online convolutional dictionary learning (SOCDL) method is proposed for unsupervised image processing tasks such as image reconstruction and inpainting. The expected reconstruction cost with respect to the dictionary is approximated via a surrogate function to enable online learning, and under the slice-based representation a second-order stochastic approximation approach is proposed for optimization. The approximation efficiently generates a dictionary sequence which converges favorably with desired characteristics for image reconstruction. Convergence analysis is presented with theoretical justifications, and the computational complexity is among the lowest within the context of online CDL algorithms with least memory consumptions. Finally, this thesis proposes a novel masked version of SOCDL which can perform online learning on incomplete data for image inpainting.