Abstract: Character codes 2 representing pictograph font characters 6 may be used to determine an address 8 within a variable length coded data stream 10 of pixel data for the whole font relevant to the character 6 concerned. This access is via a two level table lookup with the first table level Table 1 returning an initial offset HuffOff within the coded data stream, an average size AvSz of data for a character and a pointer TB2Off to a second table Table 2. The second table is then used to lookup an error value Err to correct an estimate of the address generated from the information in the first table using the error value Err and the position N within the second table Table 2 that led to the match. The pixel bitmaps 36 for pictograph characters 6 can be divided into smaller tiles 38 and each of these tiles given a code. The tile codes may then be Huffman coded to provide highly efficient compression of the pixel bitmap font data.