A method of adaptive Intra prediction, referred to as inter-layer adaptive Intra prediction, IL-AIP, for an inter-layer video coding system, wherein video data is configured into a Base Layer, BL, and an Enhancement Layer, EL, for the inter-layer video coding system, the method comprising: receiving a to-be-processed block in the EL; determining a collocated block in the BL, wherein the collocated block is located at a location in the BL corresponding to the to-be-processed block in the EL, and wherein the collocated block is Intra coded; deriving an adaptive Intra predictor for the to-be-processed block in the EL from the collocated block in the BL based on pixel data of the BL; and applying Intra prediction encoding or decoding to the to-be-processed block in the EL using the adaptive Intra predictor, characterized in that the adaptive Intra predictor corresponds to a linear function of pixel data in the collocated block according to P ′ EL = α ⋅ P ′ BL + β, wherein P' EL = P' EL (x,y) corresponds to the adaptive Intra predictor at a pixel location (x,y) for the to-be-processed block in the EL, P' BL = P' BL (x,y) corresponds to the pixel data of the collocated block at the pixel location (x,y) in the BL, and α and β are parameters, and wherein the collocated block is up-sampled before applying the linear function if the BL has lower spatial resolution than the EL, wherein α and β are derived based on a least-squares method using two pixel sets corresponding to a prediction set, PS, associated with the EL and a collocated set, CS, associated with the BL, wherein the PS is formed by sampling first boundary pixels above the to-be-processed block in the EL, and sampling second boundary pixels adjacent to the left of the to-be-processed block in the EL, and wherein the CS is formed by sampling third boundary pixels above the collocated block of the BL, and sampling fourth boundary pixels to the left of the collocated block of the BL. receiving a to-be-processed block in the EL; determining a collocated block in the BL, wherein the collocated block is located at a location in the BL corresponding to the to-be-processed block in the EL, and wherein the collocated block is Intra coded; deriving an adaptive Intra predictor for the to-be-processed block in the EL from the collocated block in the BL based on pixel data of the BL; and applying Intra prediction encoding or decoding to the to-be-processed block in the EL using the adaptive Intra predictor, characterized in that the adaptive Intra predictor corresponds to a linear function of pixel data in the collocated block according to P ′ EL = α ⋅ P ′ BL + β, wherein P' EL = P' EL (x,y) corresponds to the adaptive Intra predictor at a pixel location (x,y) for the to-be-processed block in the EL, P' BL = P' BL (x,y) corresponds to the pixel data of the collocated block at the pixel location (x,y) in the BL, and α and β are parameters, and wherein the collocated block is up-sampled before applying the linear function if the BL has lower spatial resolution than the EL, wherein α and β are derived based on a least-squares method using two pixel sets corresponding to a prediction set, PS, associated with the EL and a collocated set, CS, associated with the BL, wherein the PS is formed by sampling first boundary pixels above the to-be-processed block in the EL, and sampling second boundary pixels adjacent to the left of the to-be-processed block in the EL, and wherein the CS is formed by sampling third boundary pixels above the collocated block of the BL, and sampling fourth boundary pixels to the left of the collocated block of the BL.