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What's the difference between imagesc and imshow?

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Matlab Help Seeker
Matlab Help Seeker le 15 Avr 2013
Commenté : Image Analyst le 22 Mai 2022
Hi,
When I want to display an image in figure screen, both works the same way. I was wondering what's the difference between both imagesc and imshow commands?
Thank you.

Réponse acceptée

Adam Filion
Adam Filion le 15 Avr 2013
imshow has a number of default settings intended for displaying images, such as turning off the axes and locking the aspect ratio, that imagesc does not. imshow also had additional options for customizing how you view the image that are not available or not as easily doable through imagesc. You can see the basic differences by doing something like the following and looking at the two figures side by side.
>> imagesc(myimage)
>> figure
>> imshow(myimage)
You can get full details on the functions and their usages through their documentation pages.
>> doc imagesc
>> doc imshow
Finally you can view the source code for both if interested.
>> edit imagesc
>> edit imshow
  3 commentaires
Anand
Anand le 12 Fév 2014
I presume you're talking about the fact that the image is not magnified. This is because imshow by default displays images at 100% magnification. If you would like to change that behavior, you can update the preferences for imshow as follows:
iptsetpref('ImshowInitialMagnification','fit');
You can reset this to the default using
iptsetpref('ImshowInitialMagnification',100);
Walter Roberson
Walter Roberson le 24 Déc 2020
You can
imshow(image, [])
to have it scale the data the way imagesc() does.

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Plus de réponses (2)

pouria farhadian
pouria farhadian le 30 Avr 2018
imagesc reduce the time of our process.actually I dont know why????
  3 commentaires
Ying Yu
Ying Yu le 24 Déc 2020
Practically, I actually think pouria's answer is quite valuable. Thanks!
Walter Roberson
Walter Roberson le 24 Déc 2020
imagesc() does less work than imshow(), and changes fewer graphics settings, so it is not as "hard" on the graphics system.

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Mehri Mehrnia
Mehri Mehrnia le 22 Mai 2022
I work with cardiac MRI images(grayscale). it happens repeatedly that "imagesc" shows the image while "imshow" shows a nonsence combination of black-white point!!
I don't know the reason. Any thought?
  1 commentaire
Image Analyst
Image Analyst le 22 Mai 2022
You probably have a floating point image with values outside the range of 0 to 1. Therefore you need to use [] in imshow(
imshow(mriImage, []);
That will take whatever the actual values are and scale them to 0-255 for display. Otherwise values below 0 show as black and above 1 show as white.
imagesc automatically scales the image -- that's what the "sc" stands for. However it applies a colormap that produces a pseudocolored RGB image that is almost always not what you want. imshow() leaves it as gray scale.
With either function you can apply the colormap you want, either with the 'Colormap' option of imshow(). Or you can call the colormap() function for either imshow() or imagesc() as a function call after you call them.
cmap = turbo(255);
colormap(cmap);
colorbar

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