Run Length Encoding & Decoding in MATLAB

Run-length encoding, or RLE, is a straightforward method of lossless data compression in which runs of data, or sequences of data with the same value in many consecutive elements, are stored as a single value and count rather than as the original run.  In other words, RLE ( Run Length coding) is a straightforward technique for data compression that involves specifying the number of times a character’s or pixel’s color repeats before the character’s or pixel’s value. The goal is to use fewer bits to represent a given set of data. This method should only be used if the number of occurrences is equal to or more than four to get the benefit of compression. This method can also be optimized for replacing a group of repeated characters instead of single character.

Run Length Encoding:

By “counting” the entries in a given sequence, a counting sequence (RLE) is created.

For example, the sequence x = 2, 2, 2, 1, 1, 5, 5, 6, 6, 6, 6. can be read as Three  2’s, Two 1’s, five 2’s, four 6. which translates to b = 3, 2, 2, 1, 5, 2, 4, 6. Therefore, b is the counting pattern for a.

Example 1:

Matlab

% MATLAB CODE for encoding
clc
clear all
close all
a=input('Enter the array:');
b=[];
c=1;
for i=1:length(a)-1
    if(a(i)==a(i+1))
        c=c+1;
    else
        b=[b,c,a(i),];
    c=1;
    end
end
b=[b,c,a(length(a))];
disp(b);

Output:

For example, the sequence x =  9, 5, 1, 2, 3, 4, 5, 7  and 2, 5, 1, 2, 4, 1, 1, 3 can be read as Nine 5’s, one 2, three 4’s, five 7. Which translates to y = 5, 5, 5, 5, 5, 5, 5, 5, 5, 2, 4, 4, 4, 7, 7, 7, 7, 7

Example 2:

Matlab

% MATLAB code for decoding
clc
clear all
close all
a=input('Enter the array:');
b=[];
for i=1:2:length(a)
    b=[b a(i)];
end
c=[];
for i=2:2:length(a)
    c=;
end
u=[];
for i=1:length(b)
    n=b(i);
    r=c(i);
    for q=1:n
        u=[u r];
    end
end

Output: