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In writing some image processing routines in Matlab, I found that I don't know how to write metadata in to a newly processed and saved image. To keep it simple, my flow is as follows:

image = imread('Base_Pic.jpg'); image_info = imfinfo('Base_Pic.jpg'); %Process image... %Update metadata... imwrite(image,'Updated_Image.jpg','JPEG','Quality',100);

I basically want the newly processed image to have all the same metadata attributes as the original image, with a few fields updated of course.

How can I append the image_info structure to the newly saved JPEG?

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You have a (very) limited ability to do this in imwrite : for JPEG it only accepts BitDepth, Comment, Mode and Quality. And Mode and Quality don't get returned from iminfo. In imwrite you can do:

iminfo = imfinfo('Base_Pic.jpg') imwrite(...,'BitDepth',iminfo.BitDepth, 'Comment',iminfo.Comment);

Other than that, there isn't a way to do this with Image Processing Toolbox/Matlab as far as I know. If you have TIFF or medical images there are a number of toolboxes that do it, but I haven't ever found any for jpeg, even on the File Exchange...

If you have exiftool on your system, you can use 

[status info]=system('exiftool -s Base_Pic.jpg');

info now contains a list of tag names and tag values, e.g.:

ExifToolVersion : 8.75 FileName : Base_Pic.jpg Directory : Pictures FileSize : 2.0 MB FileModifyDate : 2011:10:27 08:41:55+10:00 FilePermissions : rw-rw-r-- FileType : JPEG MIMEType : image/jpeg JFIFVersion : 1.01 ExifByteOrder : Big-endian (Motorola, MM) Make : Apple Model : iPhone 4 ...

And if you split on colon : you can write them back using exiftool -[TAG]=[VALUE], e.g. exiftool -Make=Apple -Model="iPhone 4" ....

Or you can copy them "all" in one foul hit:

system('exiftool -overwrite_original -tagsFromFile Base_Pic.jpg Updated_Image.jpg')
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Read this : http://www.mathworks.co.uk/help/matlab/import_export/exporting-to-images.html#br_c_iz-1

under the title : "Exporting Image Data and Metadata to TIFF Files" ...

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If you aren't modifying too many of the fields you could make use of exiftool, which is an executable which can read and write exif tags.

I'd probably do something like:

image = imread('src.jpg'); image_info = imfinfo('src.jpg'); %Process image... %Update metadata... imwrite(image,'dst.jpg','JPEG','Quality',100); % copy over all the tags system('exiftool -tagsfromfile src.jpg dst.jpg'); % then use exif tool to update the specific tags ...
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