@Article{CLRS86, author = { Benny Chor and Charles E. Leiseron and Ronald L. Rivest and James B. Shearer }, title = { An application of number theory to the organization of raster-graphics memory }, acm = { 712521 }, journal = { JACM }, issn = { 0004-5411 }, OPTyear = { 1986 }, OPTmonth = { January }, date = { 1986-01 }, volume = { 33 }, number = { 1 }, pages = { 86--104 }, url = { http://doi.acm.org/10.1145/4904.4800 }, doi = { 10.1145/4904.4800 }, acmid = { 4800 }, publisher = { ACM }, keywords = { {BITBLT}, Fibonacci lattices, golden ratio, interleaving, memory organization, raster graphics, rectangles }, abstract = { A high-resolution raster-graphics display is usually combined with processing power and a memory organization that facilitates basic graphics operations. For many applications, including interactive text processing, the ability to quickly move or copy small rectangles of pixels is essential. This paper proposes a novel organization of raster-graphics memory that permits all small rectangles to be moved efficiently. The memory organization is based on a doubly periodic assignment of pixels to $M$ memory chips according to a ``Fibonacci'' lattice. The memory organization guarantees that, if a rectilinearly oriented rectangle contains fewer than $M/\sqrt{5}$ pixels, then all pixels will reside in different memory chips and thus can be accessed simultaneously. Moreover, and $M$ consecutive pixels arranged either horizontally or vertically, can be accessed simultaneously. \par We also define a continuous analog of the problem, which can be posed as: ``What is the maximum density of a set of points in the plane such that no two points are contained in the interior of a rectilinearly oriented rectangle of unit area?'' We show the existence of such a set with density $1/\sqrt{5}$, and prove this is optimal by giving a matching upper bound. }, }