A method for processing an image performed by an image processing apparatus, the method comprising: • receiving a bit stream including: ∘ an encoded flag provided in a block in a picture, the block being divided into a plurality of subblocks, wherein the flag has a first value if all sub blocks have each a difference quantization parameter equal to zero, and has a second value if at least one difference quantization parameter of the sub blocks is equal to non-zero, wherein the flag having the first value further indicates that no difference quantization parameter is present in any sub block and the flag having the second value further indicates that difference quantization parameters are present for those sub blocks having the non-zero value, ∘ only if the flag has the second value, an encoded difference quantization parameter for each subblock of the plurality of subblocks; ∘ and encoded quantized data; • decoding the bit stream to obtain the quantized data, the flag and, only if the flag has the second value, the encoded difference quantization parameters (S202) ; • determining, for each sub block, a current quantization parameter, wherein for those sub blocks having the non-zero difference quantization parameter, the current quantization parameter is calculated by using the corresponding decoded difference quantization parameter (S234); and • inversely quantizing the quantized data using the set current quantization parameters (S236). • receiving a bit stream including: ∘ an encoded flag provided in a block in a picture, the block being divided into a plurality of subblocks, wherein the flag has a first value if all sub blocks have each a difference quantization parameter equal to zero, and has a second value if at least one difference quantization parameter of the sub blocks is equal to non-zero, wherein the flag having the first value further indicates that no difference quantization parameter is present in any sub block and the flag having the second value further indicates that difference quantization parameters are present for those sub blocks having the non-zero value, ∘ only if the flag has the second value, an encoded difference quantization parameter for each subblock of the plurality of subblocks; ∘ and encoded quantized data; ∘ an encoded flag provided in a block in a picture, the block being divided into a plurality of subblocks, wherein the flag has a first value if all sub blocks have each a difference quantization parameter equal to zero, and has a second value if at least one difference quantization parameter of the sub blocks is equal to non-zero, wherein the flag having the first value further indicates that no difference quantization parameter is present in any sub block and the flag having the second value further indicates that difference quantization parameters are present for those sub blocks having the non-zero value, ∘ only if the flag has the second value, an encoded difference quantization parameter for each subblock of the plurality of subblocks; ∘ and encoded quantized data; • decoding the bit stream to obtain the quantized data, the flag and, only if the flag has the second value, the encoded difference quantization parameters (S202) ; • determining, for each sub block, a current quantization parameter, wherein for those sub blocks having the non-zero difference quantization parameter, the current quantization parameter is calculated by using the corresponding decoded difference quantization parameter (S234); and • inversely quantizing the quantized data using the set current quantization parameters (S236). <EOS>