Looking to set thresholds to an image but running into issues with the subplot?

%"sobelpic" is the name of the image.
%I'm getting an error that my subplot is too large. 
%I'm thinking that I need to manipulate my threshs (somehow?) because ultimately I need to choose "0.34" as a threshold value according to my professor.

threshs = 0.01:0.01:0.8;
   for i =1:length(threshs) 
    BW = im2bw(sobelpic,threshs(i));
    subplot(1,2,i); %I can set this to (1,2,2) to get two images but I need more to choose from. 
    imagesc(BW);
    title(['frame ',num2str(i)]);
   end
t = input('which threshold?');
BW = im2bw(sobelpic,threshs(t));
BW = imcomplement(BW);

So ultimately I'd like to see 8 images in a sublot with thresholds from 0 to 1, where 0.34 is one of them. Thank you.

Original image is uploaded, the one I'm using has the sobel filter on it, named "sobelpic" in the code.

Answer 1

[Image Analyst]

Kristin, try this. Again, no idea what you want to measure but I'm pretty sure Sobel is not the best approach. Why do you think it is?

% Demo by Image Analyst
clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
clear;  % Erase all existing variables. Or clearvars if you want.
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 20;
markerSize = 40;
%--------------------------------------------------------------------------------------------------------
%    READ IN IMAGE
fileName = 'drosophila_embryo_wild_type.jpg';
grayImage = imread(fileName);
% Get the dimensions of the image.
% numberOfColorChannels should be = 1 for a gray scale image, and 3 for an RGB color image.
[rows, columns, numberOfColorChannels] = size(grayImage)
if numberOfColorChannels > 1
    % It's not really gray scale like we expected - it's color.
    % Extract the blue channel (so the magenta lines will be white).
    grayImage = grayImage(:, :, 3);
end
%"sobelpic" is the name of the image.
%I'm getting an error that my subplot is too large.
%I'm thinking that I need to manipulate my threshs (somehow?) because ultimately I need to choose "0.34" as a threshold value according to my professor.
threshs = linspace(0.01, 0.8, 9);
%--------------------------------------------------------------------------------------------------------
% Display the image.
subplot(4, 3, 1);
imshow(grayImage, []);
impixelinfo;
axis('on', 'image');
title('Original Image', 'FontSize', fontSize, 'Interpreter', 'None');
hold on
drawnow;
% Maximize window.
g = gcf;
g.WindowState = 'maximized'
drawnow;
% Get a sobel image.
sobelPic = imgradient(grayImage,"sobel");
subplot(4, 3, 2);
imshow(sobelPic, []);
impixelinfo;
axis('on', 'image');
title('Sobel Image', 'FontSize', fontSize, 'Interpreter', 'None');
hold on
drawnow;
subplot(4, 3, 3);
histogram(sobelPic);
grid on;
xlim([0, 150]);
title('Histogram of Sobel Image', 'FontSize', fontSize, 'Interpreter', 'None');
%--------------------------------------------------------------------------------------------------------
% Compute binary image
for k =1:length(threshs)
    t = threshs(k);
    BW = im2bw(sobelPic,t);
    subplot(4, 3, k+3);
    imshow(BW, []);
    caption = sprintf('Thresholed at %.2f', t);
    title(caption);
    drawnow;
end

[Kristin Aldridge]

Thanks. I was struggling with the subplot and managed to find a work-around but couldn't get 0.34 to show. I have no choice in sobel unfortunately, my professor wants me to use it.