User profile for user: Hsinallac
Hsinallac Author
User level: Level 1
12 points

Converting large .tif files to smaller .jpg files using Preview on Mac

I have a large number of .tif files so would prefer bulk methods. Jpg allows for more versatile digital use so wish to convert bulk files of ,tif of about 26mb to .jpgs of about 2.5mbs. I will retain the .tif files for further print s that may need to be made.

I have used Preview. Load about 50 files at a time. Export to chosen folder and jpg but the slider for setting size seems not to work. It simply saves the jpg file as a 26mb file.

I seem not to find a way around this. It has worked correctly in the past.


[Re-Titled by Moderator]

Original Title: Scanned Photographs saved as .Tif files of 26mb need to be converted to Jpg files of smaller sizes like 2.5mb.


MacBook Pro 13″, macOS 15.6

Posted on Sep 10, 2025 3:39 AM

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User profile for user: Luis Sequeira1
Luis Sequeira1
User level: Level 9
73,236 points

Posted on Sep 10, 2025 3:57 AM

Converting a bunch of files to jpeg does not require a lot of work.


You can do it from Finder directly.

Make a copy of the TIFF files first, just in case; the procedure below should not delete the original, but still).


Select the files you want a jpeg version of, control-click and choose Convert Image. Choose JPEG, and click "Convert to JPEG". That's all.


Note: this already produces files that are usually much smaller, but if you feel you need more control, let me know.



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User profile for user: Luis Sequeira1
Luis Sequeira1
User level: Level 9
73,236 points

Sep 10, 2025 3:57 AM in response to Hsinallac

Converting a bunch of files to jpeg does not require a lot of work.


You can do it from Finder directly.

Make a copy of the TIFF files first, just in case; the procedure below should not delete the original, but still).


Select the files you want a jpeg version of, control-click and choose Convert Image. Choose JPEG, and click "Convert to JPEG". That's all.


Note: this already produces files that are usually much smaller, but if you feel you need more control, let me know.



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User profile for user: Matti Haveri
Matti Haveri
User level: Level 6
19,706 points

Sep 10, 2025 6:21 AM in response to Hsinallac

Maybe you have stumbled on this old Preview.app bug when it exports wrong codec. In your case it seem that the exported ".jpeg" is in fact a much larger TIFF disguised as .jpeg.


With many images selected, Preview "Export Selected Images" exports many images with a wrong codec. For example:


1. Open many images (.heic, for example) in Preview.app.

2. Edit > Select All.

3. File > Export Selected Images... > Show Options > Select some other Format (JPEG, for example).


Result: All files have .jpeg suffix and the very 1st exported file(s) might really be .jpeg but the rest are really .heic (HEIF) if you inspect them with Preview > Tools > Show Inspector > General Info.


https://discussions.apple.com/thread/255994102?answerId=261234333022&sortBy=oldest_first#261234333022


Converting multiple photos to HEIC using … - Apple Community


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Converting large .tif files to smaller .jpg files using Preview on Mac

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