# how can I plot a graph over an image in Matlab?

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DARSHAN KUMAR BISWAS on 30 Jun 2022
Commented: Adam Danz on 5 Jul 2022
I want to plot the graph over the 1st image.

Kevin Holly on 30 Jun 2022
Flip the image vertically (y-axis direction will be flipped vertically later)
exampleimage = flipud(exampleimage);
Display image
imshow(exampleimage)
Use hold on so more children can be added to the axes
hold on
Create scatter plot
x=1:20:300;
y=x;
scatter(x,y,'filled','w')
Change y-dir to normal (Note, y-dir is upside down when images are displayed by default)
set(gca,'YDir','normal') %gca stand for get current axes
Adam Danz on 5 Jul 2022

Adam Danz on 30 Jun 2022
Plot the image using image or imagesc or some other image function that allows you to specify the x and y values of the image. That way you set the image coordinates to the data coordinates.
Then just hold on and plot the data into the same axes.
Note that image functions flip the y axis so you may need to flip it back to normal using set(gca, 'YDir','Normal') or flip your data when you plot it.
If you have additional questions, share the code you've got so far and let us know specificially where you're stuck.
##### 2 CommentsShowHide 1 older comment
DARSHAN KUMAR BISWAS on 30 Jun 2022
For the graph and the image, the y-axis values are opposite to each other.

Rik on 30 Jun 2022
You need to use the same axes. The easiest solution is to use hold, probably the line below will already do what you need:
hold(gca,'on')
DARSHAN KUMAR BISWAS on 30 Jun 2022
c=a(:,:,3)-b(:,:,3);
H=fspecial("average",10);
cAvg=imfilter(c,H);
max(max(c));
min(min(c));
no_row=size(c,1);
no_col=size(c,2);
Xbox=50;
P=floor(no_col/Xbox);
k=zeros(1,4857);
x=linspace(1,Xbox,Xbox);
q=zeros(453,4857);
y=linspace(1,Xbox,Xbox);
for i=1:453
for j=1:4857
if cAvg(i,j)>10
q(i,j)=cAvg(i,j);
else
q(i,j)=5;
end
end
end
l=zeros(45,Xbox);
for m=1:45
for n=1:Xbox
l(m,n)=mean(mean(q(((m-1)*10+1):10*m,((n-1)*24+1):P*n)));
end
end
for i=1:Xbox
p=l(:,i);
for j=1:45
if p(j)>=10
o(i)=j;
break
else o(i)=45;
end
end
end
for i=1:Xbox
v=((45-o)*20)/45;
end
plot(y,v,'Bx')

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