ECG信號(hào)數(shù)字化處理技術(shù)

ECG信號(hào)是一維的數(shù)據(jù)。一般被記錄在熱敏紙上。不便于保存和處理。可以先用掃描儀，至少300DPI的分辨率，掃描下來(lái)。

使用PHOTOSHOP的旋轉(zhuǎn)將圖旋轉(zhuǎn)到正確方向。使用魔棒工具 容差50 連續(xù) 將相應(yīng)圖線選出。反選后將背景的格子顏色，及說(shuō)明去除。圖像模式改為灰度，去除顏色。再交圖像模式改為位圖。50%閾值。另存成bmp文件。

然后使用下面的程序轉(zhuǎn)換。bmp文件被讀入MATLAB中，并查找非空邊沿，然后再做一維數(shù)字化。bmp圖像轉(zhuǎn)換成對(duì)應(yīng)文件名的文本文件，文本文件可以導(dǎo)入EXCEL或其它可以接受數(shù)據(jù)的程序中。數(shù)據(jù)以科學(xué)計(jì)數(shù)法表示。

% remove blank line and digitalize
% try to find 4 boundery and put it to
% an txt file
% 4 bounder is bup bdown bleft bright
%
% usage: removeblank 'filename' filename must be a bmp file

function y = removeblank( x )
a = imread(x,'bmp');
for i = 1 : length(a(:,1))
??? if(length(find(a(i,:))) ~= 0)
??????? bup = i;
??????? break;
??? end
end
for i = length(a(:,1)) : -1 : 1
??? if(length(find(a(i,:))) ~= 0)
??????? bdown = i;
??????? break;
??? end
end?
for i = length(a(1,:)) : -1 : 1
??? if(length(find(a(:,i))) ~= 0)
??????? bright = i;
??????? break;
??? end
end?
??
for i = 1 : length(a(1,:))
??? if(length(find(a(:,i))) ~= 0)
??????? bleft = i;
??????? break;
??? end
end;
% 4 boundery found

fid = fopen(['dg',x,'.txt'],'W');

for i = bup : bdown
??? b = find(a(i, bleft : bright));
???
??? if(length(b) == 0)
??????? c(i - bup + 1) = c(i - bup)
??? else
??? c(i-bup + 1) = sum(b)/(length(b));
end
fprintf(fid,'%6d\n',c(i-bup + 1));

end;
plot(c);
fclose(fid);
%imwrite(a(bup : bdown, bleft : bright),['rb',x] ,'bmp');