Basic: calling a function
2 views (last 30 days)
Show older comments
Stina Ravdna Lorås
on 25 Jan 2021
Commented: Stina Ravdna Lorås
on 25 Jan 2021
I have a probably very basic question:
I have made a function file in matlab and want to call it within my script file. The script is not finished, so I just need to consentrate to get the function "central_difference" working for now. I get an error message saying that the variable 'greyimg' is not defined when I call central_difference. I don´t understand why, since it is defined....? And when the function works, should it not also be able to plot the subplots 152-154
Code here:
Script file:
clc;
clear all;
gridimg = im2double(imread('grid.jpg'));
grayimg = rgb2gray(gridimg);
[Ix,Iy,Im] = central_difference(greyimg);
[x,y,theta] = extract_edges(Ix, Iy, Im, edge_threshold);
figure(6);
set(gcf,'Position',[100 100 1000 300])
subplot(151); imshow(img_blur); xlim([300, 500]); title('Blurred input');
subplot(152); imshow(Ix, [-0.05, 0.05]); xlim([300, 500]); title('Gradient in x');
subplot(153); imshow(Iy, [-0.05, 0.05]); xlim([300, 500]); title('Gradient in y');
subplot(154); imshow(Im, [ 0.00, 0.05]); xlim([300, 500]); title('Gradient magnitude');
Function file:
function [Ix, Iy, Im] = central_difference(Img)
Ix = zeros(size(Img)); % Placeholder
Iy = zeros(size(Img)); % Placeholder
Im = zeros(size(Img)); % Placeholder
kernel = [1/2 0 -1/2];
for i=1: size(Img, 1) %alle rader i grayimg
Ix(i, :) = conv(Img(i,:), kernel, "same"); %conv med kernel
end
for j=1: size(Img, 2) %alle kolonner i grayimg
Iy(:, j) = conv(Img(:,j), kernel, "same");
end
Im = sqrt(Ix.^2 + Iy.^2);
end
0 Comments
Accepted Answer
Cris LaPierre
on 25 Jan 2021
Edited: Cris LaPierre
on 25 Jan 2021
The error is telling you that greyimg does not exist. When you create the variable, you call it grayimg (with an a instead of e)
grayimg = rgb2gray(gridimg);
^ % gray
[Ix,Iy,Im] = central_difference(greyimg);
^ % grey
More Answers (0)
See Also
Categories
Find more on Performance and Memory in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!