Reducing Scanned PDF File Size In ios26 Preview App

[Buadhai]

My wife asked me how to reduce the size of a PDF created by scanning a document with the Preview app. I searched and found Apple's instructions here: https://support.apple.com/en-al/guide/iphone/iph61c20afe1/ios

Go to the Preview app  on your iPhone.

Open a PDF or image.

Tap  next to the filename, then tap Export.

Select a file format.
Available formats are HEIC, JPEG, PDF, PNG, and TIFF.

Optionally, use the slider to adjust the file size.

Trouble is, when you open the PDF there is no filename shown, so nothing to select next to the filename.

I was able to find export formats, but nothing shown to adjust the size. There is no slider.

I did find out how to crop the image, but that's not what I want.

I also found how to reduce the pixel density, but that's not it either.

How stupid am I, anyway?

 

[Lab34]

Hi,
I have the file name on the top of the screen, than there are three dots. But... it's not here. 😅
Instead, in the lower part of the screen, you have the usual "share" icon, and here, under the file name, you have an "option" button, to choose the format and the file resolution.

 

[papbot]

I found the options on my phone using the Preview app. Find the file, tap on it and at the top of the item, it’s off to the left side when doing this on my iPad, there is a downward arrow next to the file name as in my first screenshot.

Then after tapping on that arrow you get the list of options and when you select Export you get the next screen in my second screenshot.

 

[papbot]

Interestingly enough I could not find the same options within the Files app. I could only get Export and the available adjustments within the Preview app.

 

[Ruggy]

In preview choose 'export' then the second drop down list says 'quartz filter'
Open the list and select 'reduce file size'.
It won't necessarily reduce it by an enormous amount though

However, the way to significantly reduce file size is to start with images that are significantly smaller.
If it's a scan they may be 2Mb or much more each and you can probably get a page of text down to about 256Kb

If you, for example, take a screen shot of each page and keep the image quality to about 90% (if it's a jpeg) and if you keep the resolution to a minimum of 72 pixels per inch, then use Preview to make a new .pdf, then you can easily make a 12mb .pdf to a maximum of about 1.6mb

If you need to resize it then 595 × 842 pixels at 72 pixels per inch should be enough but a bit bigger won't make a lot of difference in file size. That's about the minimum for an A4 but don't compress it too much. 90% is about right. Better a smaller size and a higher compression or it just gets impossible to read.

To make a .pdf from a load of jpegs
You make all the individual images, then select them all in Finder.
Rt click one then 'open with preview'
Then in the sidebar, drag them into the correct order
Then File>Print and bottom corner 'save as .pdf'

Another really useful trick in the 'print' section of Preview is making a new .pdf from just part of a .pdf.

Suppose you have a 42 page manual and you want a .pdf from just pages 3-5.
Open the print menu, select the print range from 3-5 then go to the little box at the bottom and tell it to 'make .pdf and you will have a new .pdf from just that part.
Or, choose 'open with preview' instead, then choose 'export' and with 'quartz filer'> reduce file size, you can get the smallest possible just like before.

But always try and start with a much smaller clear image for each page. That's the real trick

 

[Buadhai]

In preview choose 'export' then the second drop down list says 'quartz filter'
Open the list and select 'reduce file size'.
It won't necessarily reduce it by an enormous amount though

I don't see "export" anywhere in the iOS version of Preview.

 

[adrianlondon]

I don't see "export" anywhere in the iOS version of Preview.

They're probably talking about the MacOS or iPadOS version (I don't have an iPad so have no idea).

In the Preview app, long press on the file (without opening it) and under Quick Actions there's an option to optimise the size. In my test, a 1.2MB PDF file got compressed and saved as a ... 1.2MB file. So not much use 😁

Often, PDF files can't be reduced in size if they're very simple and no images; but for lager files especially those with images, the reduction can be noticeable.

Edit: Oh, I found it! When I open the file in Files and select the option (bottom middle of my screen) to open it in Preview, if you then click on the empty space at the top of the screen, the filename appears with a drop-down arrow at the end of it. There is an export function. That allows a PDF to be saved and optimised in size - I assume same as my long-press method above.

 

[papbot]

I don't see "export" anywhere in the iOS version of Preview.

This is from my ipad where the name you’ve given the file is off to the left. There is a downward arrow next to that name. Tap that arrow and you will see these options including Export. However, I just realized that dark mode has triggered on my devices and neither the file name nor that down arrow is visible. But knowing that is there I tapped on that spot and got it to appear so I could tap on it.

 

[papbot]

And this is from my iPhone Preview app where the file name is at the top, again in dark mode I had to tap on the spot as it’s not visible, once I did that, tapping on the the down arrow brings up the same options including Export.

 

[Love-hate 🍏 relationship]

following

 

[Buadhai]

And, Dark Mode is the answer. In Dark Mode the document name is invisible as is the all-important Down Arrow (down carat) [⌄] symbol that you need to tap to get to the Export function. I am always in Dark Mode because my old eyes are very sensitive to brightness and glare. I guess I have to remember to disable Dark Mode when dealing with Apple's minimalist UI.

Dark Mode Enabled

Dark Mode Disabled

 

[papbot]

And, Dark Mode is the answer. In Dark Mode the document name is invisible as is the all-important Down Arrow (down carat) [⌄] symbol that you need to tap to get to the Export function. I am always in Dark Mode because my old eyes are very sensitive to brightness and glare. I guess I have to remember to disable Dark Mode when dealing with Apple's minimalist UI.

Dark Mode Enabled

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Dark Mode Disabled

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Yep that’s it. I had looked earlier today both on my phone and iPad and easily found that carat, of course I had tried everything else first and then that thing. Then when I saw your previous post I went back and couldn’t find it. Got confused till I put my nose right up to the screen and realized it was still there but dark mode had kicked in and hidden it, I have it set to come on at 5pm. So now I just tap where I know it’s supposed to be and it appears. It’s odd though that those options are not available when looking at the same file in Files, you have to use Preview, which I never do.

 

[Buadhai]

Yep that’s it. I had looked earlier today both on my phone and iPad and easily found that carat, of course I had tried everything else first and then that thing. Then when I saw your previous post I went back and couldn’t find it. Got confused till I put my nose right up to the screen and realized it was still there but dark mode had kicked in and hidden it, I have it set to come on at 5pm. So now I just tap where I know it’s supposed to be and it appears. It’s odd though that those options are not available when looking at the same file in Files, you have to use Preview, which I never do.

Other apps seem to be able to detect when Dark Mode is on and change the text color accordingly. This is the Rain Viewer app. I wonder why Apple can't figure this out?

 

[papbot]

Other apps seem to be able to detect when Dark Mode is on and change the text color accordingly. This is the Rain Viewer app. I wonder why Apple can't figure this out?


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I don’t have any iOS 18 devices to compare, but my guess is that it was more legible in that software. iOS 26 has a lot of visual issues; between Liquid Glass and other 26 changes, it may take them quite a while to clear this up. Another guess of mine is that Liquid Glass is going to look far different in iOS 27.