Improve image quality, grainy words

Good morning, I'm using this script to obtain a sequences of image. The problem is that the quality of the written part, or more in general of the final image is poor. If I try to zoom the image, it is all grainy. Is there a way to improve it? I attach the script I use and an example of image I obtain.

path='C:\Users\Utente\Desktop\xtreno\imm\New Folder1';

Dir=dir(path);

c=figure('Visible','off');

h1=subplot(1,2,1)

annotation(c,'line',[0.733928571428571 0.7875],[0.4 0.4],'Color',[1 0 0],'LineWidth',1);

annotation(c,'textbox',[0.779571428571429 0.354761904761906 0.131142857142857 0.107142857142858],'String',{'PROBE'},'FontSize',12,...

'FitBoxToText','off',...

'EdgeColor','none');

for i=1:17

h1=subplot(1,2,1)

hold on

plot(t1(1:i),s11(1:i),'Marker','x','LineStyle','--') %s1t1 camera, s3tefibra

if i<1

plot(t2(1:i),s3(1:i),'LineWidth',2)

else

plot(t2(1:i*10-7),s3(1:i*10-7),'LineWidth',2)

end

line([t1(i) t1(i)],[-2 2],'Color',[0 0 0]);

ylabel({'Phase (-)'},'FontName','Times New Roman');

xlabel({'t (s)'},'FontAngle','italic','FontName','Times New Roman');

legend1 = legend({'Camera','Fibre'});

h2=subplot(1,2,2)

I=imread([path,'/',Dir(2+i).name]);

imshow(I);

box(h1,'on');

h1.Position=[0.13 0.135714285714286 0.5075 0.789285714285715];

set(h1,'FontSize',10,'LineWidth',1.5,'XGrid','off','YTick',[0.2 0.9],'YTickLabel',{'Liq', 'Vap'},'XLim',[t1(i)-0.2,t1(i)+0.05],'XLimMode','Manual','YLim',[-0.2,1.2],'YLimMode','Manual');

F = getframe(c);

F1(:,:,:,i) = F.cdata;

imwrite(F1(:,:,:,i), sprintf('frame%d.png', i));

end

[Rik]

Your image is apparently fairly small. You can either increase the size of your figure, or use a different function that allows you to set the resolution (like @yanqi liu suggested).

[alessandro mutasci]

yes you are right, I tried the function that @yanqi liu suggested, but it's still grainy. Could you tell me how to increse the size of my figure please?

Answer 1

[yanqi liu]

sir，please use

print(gcf,'-dpng','-r200','your_image_name')

[Rik]

Two remarks:

1. It is better to use explicit handles for all you graphics objects. So you should use an explicit handle to your figure when creating the axes etc. That will avoid any issues due to user interaction.
2. If this quality is not enough you can change '-r200' to a higher DPI setting. It should accept most reasonable inputs.

[alessandro mutasci]

yes, using an higer DPI, it is going ok. but now I'm trying to use it for all images but it's not working. it says that there are multiple error, but I'm not understanding how to solve it.

for i=1:16

I=sprintf('frame%d.png',i)

print(I,'-dpng','-r1000','your_image_name%d')

end

[Rik]

You received an error. Now it is time to read the documentation of that function. You didn't do that yet, but you should.