how to write looping for certain area determine

Dear all,

I wrote some script looping to determine the thresh value for certain Area (267). But I got error like below. The set imageas data set as attached.

Actually, my original script is like below:

seedR1 = 58; seedC1 = 76; seedP1 = 45;
W = graydiffweight(spect, seedC1, seedR1, seedP1, 'GrayDifferenceCutoff', 1000000000);
thresh =0.0001;
[BW, D] = imsegfmm (W, seedC1, seedR1, seedP1, thresh);
T = regionprops('table', BW,'Area','Centroid')
Area             Centroid         
____    __________________________
12     75.833    58.167      44.5

Then I have to change the thresh (try and error) until I got the Area is 267.

But I want to do something like looping or iteration, which is I set the Area is 267. Then wrote the script like below:

seedR1 = 58; seedC1 = 76; seedP1 = 45;
W = graydiffweight(spect, seedC1, seedR1, seedP1, 'GrayDifferenceCutoff', 1000000000);
for thresh =0.0001:0.0001:0.9999
    [BW, D] = imsegfmm (W, seedC1, seedR1, seedP1, thresh);
    T = regionprops('table', BW,'Area','Centroid');	
    if T{1,1}==267
        gray_weight = thresh;
        volume = T{1,1};
    end
end

Can anyone help me?

Answer 1

[Walter Roberson]

Have you considered using fzero or fsolve? Those could use slope information to zoom in on the appropriate thresh

The objective would be something along the lines of

accept parameter Th. Use it with the segmm. Regionprops to get the area. Return area minus 267.

fzero or fsolve would then supply trial thresholds and would search for one that made the function zero. The function is area minus 267 so a zero for the difference would be equivalent to having searched for the threshold that gave an area of 267

[mohd akmal masud]

Dear @Walter Roberson,

Is it like this:

seedR1 = 58; seedC1 = 76; seedP1 = 45;
W = graydiffweight(spect, seedC1, seedR1, seedP1, 'GrayDifferenceCutoff', 1000000000);
for thresh =0.0001:0.0001:0.9999
    [BW, D] = imsegfmm (W, seedC1, seedR1, seedP1, thresh);
    T = regionprops3( BW,'Volume');	
    if T(1)==26.67
        gray_weight = thresh;
        volume = T(1);
        break
    end
end

Error using ()

Subscripting into a table using one subscript (as in t(i)) is not supported. Specify a row

subscript and a variable subscript, as in t(rows,vars). To select variables, use t(:,i) or for

one variable t.(i). To select rows, use t(i,:).

[Walter Roberson]

No, there would be no loop involved. It would look like this

Target_Volume = 26.67;

seedR1 = 58; seedC1 = 76; seedP1 = 45;
W = graydiffweight(spect, seedC1, seedR1, seedP1, 'GrayDifferenceCutoff', 1000000000);

fun = @(thresh)findvol(W, seedC1, seedR1, seedP1,thresh,Target_Volume);
[greyweight, residue] = fzero(@(thresh)findvol(thresh,Target_Volume), [0.0001, 0.9999]);
volume = residue + Target_Volume;

greyweight
volume

function residue = findvol(W, seedC1, seedR1, seedP1, thresh, Target_Volume)
    [BW, D] = imsegfmm (W, seedC1, seedR1, seedP1, thresh);
    T = regionprops3(W,'Volume');	
    residue = T(1).Volume - Target_Volume;
end

If it were important to you that the threshold be exactly 4 digits (quantized) instead of "whatever representable value in the range that matches the volume) then the code would need a small adjustment.

[mohd akmal masud]

Dear @Walter Roberson,

Got error

Target_Volume = 26.67;
seedR1 = 58; seedC1 = 76; seedP1 = 45;
W = graydiffweight(spect, seedC1, seedR1, seedP1, 'GrayDifferenceCutoff', 1000000000);
fun = @(thresh)findvol(W, seedC1, seedR1, seedP1,thresh,Target_Volume);
[greyweight, residue] = fzero(@(thresh)findvol(thresh,Target_Volume), [0.0001, 0.9999]);
volume = residue + Target_Volume;
greyweight
volume
function residue = findvol(W, seedC1, seedR1, seedP1, thresh, Target_Volume)
[BW, D] = imsegfmm (W, seedC1, seedR1, seedP1, thresh);
T = regionprops3(W,'Volume');	
residue = T(1).Volume - Target_Volume;
end

Error using fzero>localFirstFcnEvalError

FZERO cannot continue because user-supplied function_handle ==>

@(thresh)findvol(thresh,Target_Volume) failed with the error below.

Not enough input arguments.

Error in fzero (line 231)

localFirstFcnEvalError(FunFcn,FunFcnIn,ME);

[mohd akmal masud]

Dear @Walter Roberson,

I tried this one, but the new error appear

Target_Volume = 26.67;
seedR1 = 58; seedC1 = 76; seedP1 = 45;
W = graydiffweight(spect, seedC1, seedR1, seedP1, 'GrayDifferenceCutoff', 1000000000);
fun = @(thresh)findvol(W,thresh,Target_Volume);
[greyweight, residue] = fzero(@(thresh)findvol(W,seedC1,seedR1, seedP1, thresh,Target_Volume), [0.0001, 0.9999]);
volume = residue + Target_Volume;
greyweight
volume

function residue = findvol(W, seedC1, seedR1, seedP1, thresh, Target_Volume)
[BW, D] = imsegfmm (W, seedC1, seedR1, seedP1, thresh);
T = regionprops3(BW,'Volume');	
residue = T(1).Volume - Target_Volume;
end

Error using fzero>localFirstFcnEvalError

FZERO cannot continue because user-supplied function_handle ==>

@(thresh)findvol(W,seedC1,seedR1,seedP1,thresh,Target_Volume) failed with the error below.

Subscripting into a table using one subscript (as in t(i)) is not supported. Specify a row

subscript and a variable subscript, as in t(rows,vars). To select variables, use t(:,i) or for

one variable t.(i). To select rows, use t(i,:).

Error in fzero (line 231)

localFirstFcnEvalError(FunFcn,FunFcnIn,ME);

[Image Analyst]

Try

residue = T.Volume(1) - Target_Volume;

[mohd akmal masud]

Dear @Image Analyst

% Read main set data
clc
clear all
close all
[spect map]=dicomread('2.dcm');
info = dicominfo('2.dcm');
%gp=info.SliceThickness;
spect=(squeeze(spect));%smooth3
Target_Volume = 26.67;
seedR1 = 58; seedC1 = 76; seedP1 = 45;
W = graydiffweight(spect, seedC1, seedR1, seedP1, 'GrayDifferenceCutoff', 1000000000);
fun = @(thresh)findvol(W, seedC1, seedR1, seedP1,thresh,Target_Volume);
[greyweight, residue] = fzero(@(thresh)findvol(W, seedC1, seedR1, seedP1,thresh,Target_Volume), [0.0001, 0.9999]);
volume = residue + Target_Volume;
greyweight
volume
function residue = findvol(W, seedC1, seedR1, seedP1, thresh, Target_Volume)
[BW, D] = imsegfmm (W, seedC1, seedR1, seedP1, thresh);
T = regionprops3(BW,'Volume');	
residue = T.Volume(1) - Target_Volume;
end

Error using fzero

Function values at the interval endpoints must differ in sign.

[Walter Roberson]

% Read main set data
[spect map]=dicomread('2.dcm');
info = dicominfo('2.dcm');
%gp=info.SliceThickness;
spect=(squeeze(spect));%smooth3
Target_Volume = 26.67;
seedR1 = 58; seedC1 = 76; seedP1 = 45;
W = graydiffweight(spect, seedC1, seedR1, seedP1, 'GrayDifferenceCutoff', 1000000000);
fun = @(thresh)findvol(W, seedC1, seedR1, seedP1,thresh,Target_Volume);
[greyweight, residue] = fzero(fun, [0.0001, 0.9999]);
volume = residue + Target_Volume;
greyweight
volume
function residue = findvol(W, seedC1, seedR1, seedP1, thresh, Target_Volume)
[BW, D] = imsegfmm (W, seedC1, seedR1, seedP1, thresh);
T = regionprops3(BW,'Volume');	
residue = T.Volume(1) - Target_Volume;
end

However this will probably have the same problem about endpoints must differ in sign.

When you have this situation, a function whose endpoints do not differ in sign, then it means that there are an even number of matching points in the range. That is, possibly there is no point at all in the range that matches; possibly there are two points; or four points, or six points... Any of those is a problem for you: your situation is not designed to be able to handle no solutions and is not designed to be able to handle multiple solutions.

[mohd akmal masud]

Dear @Image Analyst @Walter Roberson,

yah, I have tried the same problem.

% Read main set data
[spect map]=dicomread('I-131sphere10nisbah1.dcm');
info = dicominfo('I-131sphere10nisbah1.dcm');
%gp=info.SliceThickness;
spect=(squeeze(spect));%smooth3
Target_Volume = 26.67;
seedR1 = 58; seedC1 = 76; seedP1 = 45;
W = graydiffweight(spect, seedC1, seedR1, seedP1, 'GrayDifferenceCutoff', 1000000000);
fun = @(thresh)findvol(W, seedC1, seedR1, seedP1,thresh,Target_Volume);
[greyweight, residue] = fzero(fun, [0.0001, 0.01]);
volume = residue + Target_Volume;
greyweight
volume
function residue = findvol(W, seedC1, seedR1, seedP1, thresh, Target_Volume)
[BW, D] = imsegfmm (W, seedC1, seedR1, seedP1, thresh);
T = regionprops3(BW,'Volume');	
residue = T.Volume(1) - Target_Volume;
end

Error using fzero

Function values at the interval endpoints must differ in sign.

But its ok. Thank you both of you sir because spent time to help me try to resolve my problem. Thank you so much. both you are awesome. :)

[Walter Roberson]

% Read main set data
[spect map]=dicomread('I-131sphere10nisbah1.dcm');
info = dicominfo('I-131sphere10nisbah1.dcm');
%gp=info.SliceThickness;
spect=(squeeze(spect));%smooth3
Target_Volume = 26.67;
seedR1 = 58; seedC1 = 76; seedP1 = 45;
W = graydiffweight(spect, seedC1, seedR1, seedP1, 'GrayDifferenceCutoff', 1000000000);
fun = @(thresh)findvol(W, seedC1, seedR1, seedP1,thresh,Target_Volume);

nvars = 1;
A = []; b = []; Aeq = []; beq = []; lb = 0.0001; ub = 0.01; nonlcon = [];
gafun = @(thresh) fun(thresh).^2;

greyweight = ga(gafun, nvars, A, b, Aeq, beq, lb, ub, nonlcon);
residue = fun(greyweight);
volume = residue + Target_Volume;

greyweight
volume

function residue = findvol(W, seedC1, seedR1, seedP1, thresh, Target_Volume)
[BW, D] = imsegfmm (W, seedC1, seedR1, seedP1, thresh);
T = regionprops3(BW,'Volume');	
residue = T.Volume(1) - Target_Volume;
end