A method for the scaling down of data is provided. At least two blocks of
transformed data samples representing at least two blocks of original
data samples are received. One of at least two tables of constants is
selected wherein each table of constants is capable of reducing the
number of transformed data samples by a different factor. The constants
taken from the selected table are applied to the at least two blocks of
transformed data samples to produce one block of transformed data samples
representing one block of final data samples. The data is processed one
dimension at a time by multiplying the data in one dimension with
selected constants taken from previously developed tables corresponding
to the desired scale down factor. Scaling down by different factors in
each dimension as well as scaling down in one dimension and scaling up in
the other dimension may be achieved. In addition, the de-quantization of
the quantized transform coefficients may be accomplished by
pre-multiplication of the selected constants when the quantization values
are known. In a similar way the re-quantization may be accomplished by a
pre-division of the selected constants. Both de-quantization and
re-quantization may be combined when the input quantized transform
coefficients and output quantized transform coefficients are desired.