hi im trying to get the vertical profiling of a braille document but im getting this kind of error..help will be much appreciated..the error is at the end of the line of codes..thankyou so much!

%vertical profiling
yProfile = mean('z');                        %peak profile

ac = xcov(yProfile);                        %cross correlation

p1 = diff(ac([1 1:end]));

p2 = diff(ac([1:end end]));

maxima = find(p1>0 & p2<0);                 %peak locations

estPeriod = round(median(diff(maxima)))     %spacing estimate

seLine = strel('line',estPeriod,0);

yProfile2 = imtophat(yProfile,seLine);      %background removed

level = graythresh(yProfile2/255);          %automatic threshold level

bw = im2bw(yProfile2/255,level);            %binarized peak regions

L = bwlabel(bw);                            %labeled regions

stats = regionprops(L);

centroids = [stats.Centroid];               %centroids

yCenters = centroids(1:2:end)               %Y parts only

gap = diff(yCenters)/2;                     %inner region half widths

first = yCenters(1)-gap(1);

% list defining vertical boundaries between spot regions

yGrid = round([first yCenters(1:end)+gap([1:end end])])

estPeriod =

     NaN

yCenters =

       1

Attempted to access gap(1); index out of bounds because
numel(gap)=0.

Answer 1

[Walter Roberson]

What are you expecting

yProfile = mean('z');                        %peak profile

to do?

What it is going to do is return the average value out of the character vector that contains the literal string 'z'. That character vector is only one element long so the mean() of it is the same as its numeric value, double('z') which is the scalar 122.

Everything else in your code falls apart because it is a scalar rather than a non-constant image.