A method for filtering an image by a decoding apparatus, the method comprising: determining whether a slice is an I-slice, and if the slice type is I-slice determining that a channel type is chroma, and if the channel type is chroma: deriving boundaries of a block of the image which is divided in a block partitioning structure including a quad-tree structure plus a binary-tree structure; determining whether the block is subdivided into a quad-tree structure; determining, based on that the block is not subdivided into the quad-tree structure, whether the block is subdivided into a binary-tree structure; determining, based on that the block is not subdivided into the binary-tree structure, a boundary strength for the block; and performing (S3321, S3323) de-blocking filtering on a reconstructed picture sample based on the boundary strength, characterized in that the method further comprises: checking whether the slice to which the current block belongs is the I-slice, and if the slice to which the current block belongs is not the I-slice determining whether the current block is a luma block, if the slice to which the current block belongs is determined as the I-slice, or if the current block is determined as a luma block, performing filtering on the edges of the luma block based on the boundary strength; and filtering at the block boundaries of the chroma block in the same way as performed on the luma component, and if the current block is not a luma block performing filtering on the edges of the chroma block based on the boundary strength. determining whether a slice is an I-slice, and if the slice type is I-slice determining that a channel type is chroma, and if the channel type is chroma: deriving boundaries of a block of the image which is divided in a block partitioning structure including a quad-tree structure plus a binary-tree structure; determining whether the block is subdivided into a quad-tree structure; determining, based on that the block is not subdivided into the quad-tree structure, whether the block is subdivided into a binary-tree structure; determining, based on that the block is not subdivided into the binary-tree structure, a boundary strength for the block; and performing (S3321, S3323) de-blocking filtering on a reconstructed picture sample based on the boundary strength, characterized in that the method further comprises: checking whether the slice to which the current block belongs is the I-slice, and if the slice to which the current block belongs is not the I-slice determining whether the current block is a luma block, if the slice to which the current block belongs is determined as the I-slice, or if the current block is determined as a luma block, performing filtering on the edges of the luma block based on the boundary strength; and filtering at the block boundaries of the chroma block in the same way as performed on the luma component, and if the current block is not a luma block performing filtering on the edges of the chroma block based on the boundary strength. checking whether the slice to which the current block belongs is the I-slice, and if the slice to which the current block belongs is not the I-slice determining whether the current block is a luma block, if the slice to which the current block belongs is determined as the I-slice, or if the current block is determined as a luma block, performing filtering on the edges of the luma block based on the boundary strength; and filtering at the block boundaries of the chroma block in the same way as performed on the luma component, and if the current block is not a luma block performing filtering on the edges of the chroma block based on the boundary strength.