Method of converting a digital data signal having a first length into a digital data signal having a second length

A signal conversion method wherein a digital video signal which includes first words each including N.sub.1 bits representing a value of one sample in a video image is converted into a digital video signal which includes second words each including N.sub.2 bits (N.sub.1 and N.sub.2 being integers and N.sub.2 <N.sub.1) representing a value of one sample, comprising the steps of:

• separating each of said first words corresponding to each of a plurality of scanning lines into a first portion which includes said N.sub.2 bits including a most significant bit and a second portion which includes of the remaining (N.sub.1 -N.sub.2) bits including a least significant bit;
• storing said first portions of said first words in a first memory means;
• composing third words, each of which includes N.sub.2 bits, by sequentially arranging at least one of said second portions of said first words;
• storing said third words in a second memory means;
• composing a first group of words by sequentially arranging said first portions of said first words stored in said first memory means;
• composing a second group of words by sequentially arranging said third words;
• and
• composing a converted digital video signal corresponding to one scanning line by sequentially arranging said second group of words after said first group of words.

A signal conversion method wherein a digital video signal which includes first words, each including N.sub.1 bits representing a value of one sample in a video image is converted into a digital video signal which includes second words each including N.sub.2 bits (N.sub.1 and N.sub.2 being integers and N.sub.2 <N.sub.1) representing a value of one sample, comprising the steps of:

• separating each of said first words corresponding to each of a plurality of scanning lines into a first portion which includes said N.sub.2 bits including a most significant bit and a second portion which consists of the remaining (N.sub.1 -N.sub.2) bits including a least significant bit;
• storing said first portions of said first words in a first memory means;
• storing said second portions of said first words in a second memory means;
• composing third words, each of which includes N.sub.2 bits, by sequentially arranging at least one of said second portions of said first words;
• composing a first group of words by sequentially arranging said first portions of said first words stored in said first memory means;
• composing a second group of words by sequentially arranging said third words;
• and
• composing a converted digital video signal corresponding to one scanning line by sequentially arranging said second group of words one of before and after said first group of words.