Graphical image recasting

Abstract

A merge computer instruction is capable of interleaving respective bytes of two four-byte words and is used once to group most significant bytes and least significant bytes of first and second pixel components represented in a two-byte format and to group most significant bytes and least significant bytes of third and fourth pixel components represented in the two-byte format and a second time to group the most significant bytes of the first, second, third, and fourth pixel components and to group the least significant bytes of the first, second, third, and fourth pixel components. The least significant bytes of the first, second, third, and fourth pixel components represent the first, second, third, and fourth pixel components in a one-byte format and are stored as the respective pixel components in the one-byte format. Thus, four pixel components are converted from a two-byte format to a one-byte format using only two computer instructions. Eight contiguous bytes can be accessed in a single read computer instruction or a single write computer instruction. Accordingly, two read computer instructions retrieve eight pixel components in a two-byte format. The eight pixel components are converted to a one-byte format using four merge computer instructions and are stored in memory using a single write computer instruction. Accordingly, a four-band graphical image which includes one million pixels can be converted from a two-byte processing format to a one-byte display format using one million read computer instructions, one-half million merge computer instructions, and one-half million write computer instructions.