A method of analysing a JPEG-compressed digital image, the JPEG-compressed digital image being represented as a bitstream, wherein said bitstream represents sequential image blocks, each image block being represented by one or more data units representing one or more components in a respective image block and each data unit being represented as a Huffman-coded stream of coefficients (36, 36') of basis functions, wherein a zeroth order coefficient is represented as a difference to the zeroth order coefficient of the preceding data unit of the same component, said method comprising: sequentially stepping through the bitstream, and while stepping through the bitstream storing, for each image block, an indicator in a block information table (30, 30') that points to the first zeroth order coefficient or to the first first order coefficient representing respective image block, which block information table (30, 30') is stored in a random-access memory, decoding the zeroth order coefficients and storing in the block information table the zeroth order coefficient of at least one data unit of each component, said zeroth order coefficient being represented in a non-differential form, and storing in the block information table information indicating the number of bits in the bitstream between coefficients of zeroth or first order in adjacent data units of the image block, wherein said decoding comprises stepping through non-zeroth order coefficients of a data unit in the bitstream, said non-zeroth order coefficients being represented by a sequence of bitstream entries, comprising: looking at a bit sequence of a predetermined number of bits in the bitstream, making a table lookup to determine the cathegory and zero run length of at least the first bitstream entry in the bit sequence and to determine the bit length of the first bitstream entry, wherein the cathegory determines the number of bits of the part of the bitstream entry encoding the actual value of the coefficient skipping the number of bits in the bitstream corresponding to the determined bit length, summing the number of skipped bits for gathering information regarding the number of bits in the bitstream between coefficients of zeroth or first order in adjacent data units, and summing the number of coefficients having been stepped through until all coefficients of the data unit have been stepped through or an end of block symbol is encountered. sequentially stepping through the bitstream, and while stepping through the bitstream storing, for each image block, an indicator in a block information table (30, 30') that points to the first zeroth order coefficient or to the first first order coefficient representing respective image block, which block information table (30, 30') is stored in a random-access memory, decoding the zeroth order coefficients and storing in the block information table the zeroth order coefficient of at least one data unit of each component, said zeroth order coefficient being represented in a non-differential form, and storing in the block information table information indicating the number of bits in the bitstream between coefficients of zeroth or first order in adjacent data units of the image block, wherein said decoding comprises stepping through non-zeroth order coefficients of a data unit in the bitstream, said non-zeroth order coefficients being represented by a sequence of bitstream entries, comprising: looking at a bit sequence of a predetermined number of bits in the bitstream, making a table lookup to determine the cathegory and zero run length of at least the first bitstream entry in the bit sequence and to determine the bit length of the first bitstream entry, wherein the cathegory determines the number of bits of the part of the bitstream entry encoding the actual value of the coefficient skipping the number of bits in the bitstream corresponding to the determined bit length, summing the number of skipped bits for gathering information regarding the number of bits in the bitstream between coefficients of zeroth or first order in adjacent data units, and summing the number of coefficients having been stepped through until all coefficients of the data unit have been stepped through or an end of block symbol is encountered. looking at a bit sequence of a predetermined number of bits in the bitstream, making a table lookup to determine the cathegory and zero run length of at least the first bitstream entry in the bit sequence and to determine the bit length of the first bitstream entry, wherein the cathegory determines the number of bits of the part of the bitstream entry encoding the actual value of the coefficient skipping the number of bits in the bitstream corresponding to the determined bit length, summing the number of skipped bits for gathering information regarding the number of bits in the bitstream between coefficients of zeroth or first order in adjacent data units, and summing the number of coefficients having been stepped through until all coefficients of the data unit have been stepped through or an end of block symbol is encountered.