2. Algorithmization for serial computers
In processing digital images the primary contradiction between the sequen
tial storage of digital images and a logical two-dimensionality of real
images becomes obviously. Leaving out future digital two-dimensional storages
and two-dimensionally working computers, so at present only an algorithmical
solution of this contradiction is possible.
These contradictions can be solved on two levels:
(1) reduction of higher-dimensional algorithms to an one-dimensional
principle or
(2) more-dimensional data supply for special array processors.
Most present solutions move on level (1), because these solutions are only
limited in regard of the possibilities of computer technology (e. g. main
memory size, access time, "free moving" in the data set). Future solutions
will more tend to level (2), whereby the processes in the computer are
becoming more an more similar to those, proceeding in the human eye-brain-
system. Increasingly methods of artificial intelligence will be used thereby
(see also /2/). For methods of digital image processing - i. e., for digital
photogrammetric methods, too - the position discretization in equal distances
is a decisive precondition for constructively reaching algorithmic solutions.
This regularity transforms - from the mathematical point of view - the repre
sentation form from integrals to series. Exactly this transition provides the
functional analytical path to an uniform model of analogue and digital methods.
The most important mathematical backgrounds for this are the existence of a
discrete eigenfunction system in the form of harmonic functions as well as the
HILBERT space equivalence between the spaces of the square-integral functions
L 2 and the square-summable series l 2 (see /1, 3/).
3. Examples for algorithmic reduction
In /4/ a row-invariant transformation method is presented. Thereby local
scale variations, which shall correct the area distortions, are carried out
by local stretchings and shrinkings within the image row - hence realized
one-dimensionally. On account of the charakteristics of the correction
function (small increase, piecewise linearizable) this transformation can be
realized as a direct transformation without extensive resampling. Also in /4/