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resizing all images in a folder

Asked by Victoria Lawlor on 28 Sep 2015
Latest activity Commented on by Jon
on 29 Sep 2015
I am able to get matlab to resize and save an individual image, but I'm wondering how I can get it to do this for all images in a folder without having to type in the names one by one. The names of the saved & original images must stay the same if that makes any difference. Could I load the images into an array and then have it loop through each image? Sorry if this is a dumb question!

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2 Answers

Answer by Jon
on 28 Sep 2015
 Accepted Answer

Yep. Try the following function:
dc = dir('*.jpg');
but set the filetype to whatever the images are. Make sure your working directory is the one with the images, obviously. The 'dc' variable will be structure that contains the file information, which will allow you to automate the loading, resizing, and saving of each image.

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Jon
on 29 Sep 2015
I skimmed through the 'dir' help file and didn't pick up that this was possible. I learned something today. I use cd often without any problems, so never occurred to me to avoid it.
For example, let's say your images were in C:\whatever, and your m-files were in C:\m-files. Now if you ran the script and called cd('c:\whatever') and then tried to call resize_and_save() function, it would not find it (unless you had made sure that folder was on the path) because the current folder is no longer C:\m-files.
I literally have hundreds of projects each in their own folder (because they're unrelated). I do not want to clutter my path with hundreds of folders, some of which I rarely use anymore, so usually I do not add my folder to the search path.
Jon
on 29 Sep 2015
I see. I've just been doing
cd('c:\whatever')
load data
cd('working_path')
I guess it's a little uglier and has the potential for problems if I'm running code line-by-line.

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Answer by Image Analyst
on 28 Sep 2015

See the FAQ for code to do this:
Put your calls to imread(), imresize() and imwrite() inside the loop.

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Like I mentioned before I haven't used matlab very much. I understand how I would load the whole file but I'm still not sure how I would have it go through each image individually. If the dir function loads the images into an array then maybe the issue is more that I don't understand how to go through each part of an array and perform some action.
I'm not sure what arguments I would put in the imread, imresize, and imwrite functions since before I had the image name.

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