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Mac OS

  • in Mac OS
  • 1 min read

AirDrop on macOS working unreliably

This post is archived. It is left as is and won't receive updates.

AirDrop is quite convenient to send files to a colleague or another device without having to send an email or uploading it somewhere. At some point (I forgot with which exact OSX version), AirDrop was updated and required Bluetooth. Since then, it often occurs that the device I want to share a file with does not appear. However, there is this option to "Search for older Macs". In the past, I've only used it to send files to a Mac running an older OSX version.

However, as it turns out, even for newer macOS versions, if this is done on both devices, it works much better and the device appears almost immediately.

  • in Mac OS
  • 2 min read

Reducing file size of a PDF on Mac OS

The file size of PDFs can become quite large, especially when scanning documents or documents containing images. Instead of sending large files, it is almost always recommended to reduce the file size. To do that, there are several ways. For example, there is an app called PDF Squeezer in the Mac App Store (in 2013: €3.59 or $3.99, more expensive today).

The same functionality can be achieved using Quartz filters in the ColorSync Utility. There is already one called Reduce File Size but it might lead to a blurry PDF. You can copy this filter and adjust the settings. However, I found custom filters in the Apple Support Community that work quite well.

  • Download the filters
  • Move the filters to ~/Library/Filters
  • Open your PDF with ColorSync Utility
  • In the bottom, choose the appropriate filter. There are several options starting with "Reduce to ..."
  • Click "Apply"
  • If you are satisfied with the result, save the file under a different file name (File > Save As).

Alternatively, you can place them into /Library/PDF Services/ instead. Besides the fact that the filters will be available to all system users, when exporting PDFs in Preview, you can select a filter directly in the dropdown under Quartz Filters.

If the filters don't work perfectly for your use, you can adjust the settings within the ColorSync Utility.

The original creator of the filters to be credited seems to be Jerome Colas according to this GitHub repository.

Updates to this blog post

  • December 2017: Uploaded the ZIP file to my own server, since the original link became unavailable.
  • 27.10.2024: Replaced ZIP file with link to GitHub repository to download filters
  • in Mac OS
  • 1 min read

Mac OS: Airport not connecting automatically to Wi-Fi

This post is archived. It is left as is and won't receive updates.

A few weeks ago I helped a friend with an issue he had on an iMac with the Wi-Fi. After a while AirPort stopped from connecting automatically to the Wi-Fi. Although this can be caused by various different issues I want to describe the one I found. All the other instructions can be easily found on the web with the search engine of your choice.

If the Wi-Fi uses a hidden SSID it can often cause problems. This was not the cause here though. Although it doesn't really increase the security (because there are tools you can use that reveal it) it can help on a social basis when people just shouldn't see that there is a Wi-Fi.

Anyways. As a side note: There were two iMacs set up the same way. One worked fine but the other didn't so something must have been different between the two. A lot of tips didn't help but they could help in your case. In this case the problem was caused by the fact that the SystemPreferences application was moved out of it's original place. After moving it back to the Application directory (/Applications) and restarting the machine it worked fine again. I suspect this could cause more problems than the one described here.