How to compress a location map using JBig compression?

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Aarach Sap 2016-9-26

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https://ww2.mathworks.cn/matlabcentral/answers/304470-how-to-compress-a-location-map-using-jbig-compression

关闭： Walter Roberson 2016-9-26

function [y,nbr_bits] = perform_jbig_coding(x)

name_pbm = 'b.pbm'; name_jbg = 'c.jbg'; if size(x,1)>1 && size(x,2)>1 % forward transform % save as pbm imwrite(rescale(x), name_pbm, 'pbm'); % convert to jgib !pbmtojbg tmp.pbm tmp.jbg % read jbig file fid = fopen(name_jbg); if fid<0 error('Unable to open Jbig file.'); end [y,cnt] = fread(fid, Inf); fclose(fid); nbr_bits = length(y)*8; % remove tmp files !del tmp.jbg !del tmp.pbm else % backward transform fid = fopen(name_jbg, 'wb'); if fid<0 error('Unable to open Jbig file.'); end fwrite(fid, x); fclose(fid); % convert to pbm !jbgtopbm tmp.jbg tmp.pbm % read pbm y = imread(name_pbm); % remove tmp files !del tmp.jbg !del tmp.pbm nbr_bits = -1; end

Actually, I find this code in matlab. But I don't understand why two ".pbm" and ".jbg" are needed. I have only one location map(.pbm) to compress. As I am very new to programming, it is really hard to understand. Please help me.