Open and convert WebP files on Mac

Yesterday I received a batch of pictures from a customer that I was supposed to exchange on her website. In the first email I thought the files were defective because the images were not displayed in Apple Mail and only strange placeholders with question marks were visible in the mail. I only knew that from broken JPEG photos.

I asked the customer to send me the files again, but the second mail looked the same. When I then looked at the attachments with the paperclip symbol in Apple Mail, I saw the file extension "webp" and it was already clear to me: this is the reason for the display problems. Consequently, my Apple Mail crashed less than 5 seconds later - probably because it was so shocked to discover "WebP" files.

Mac crash due to WebP?

[Fun mode] The reaction of my MacBook Pro is understandable, since the WebP format was created by Google and Apple of course has to refuse to cooperate. For this reason, macOS probably has a random crash sequence built into it, which is started whenever you want to open a WebP file on the Mac. [/ Fun mode]

WebP is Google's HEIC

While Apple is relying on a new compression system from its own home with HEIC, Google has a reduction in all graphic and photo files on the web on its agenda with the WebP standard. Unfortunately, WebP is (not yet) natively supported by Apple's operating system, so that interestingly, although the files are displayed in Quicklook (highlight the file and press the space bar), they cannot be opened in the preview.

If you want to read more about the compression technology of WebP, you will find a suitable document from Google here: Compression Techniques (of WebP).

Quick help: WebP ad with Google Chrome

If you just want to take a quick look at a WebP file, you can also use the Google Chrome browser. This of course understands the image format and displays the graphics accordingly. Quicklook also seems to be able to handle the files (at least for me). But changes cannot be made with it.

Modify and convert WebP files on Mac

I now had to get the files in a format that I can open in Photoshop. At the time of Mojave, I once installed a Photoshop plug-in that enables the import of WebP files (see here ). Unfortunately, the plugin became unusable after switching to Catalina, because I now only get a message that the "WebPFormat.plugin" plugin does not come from a verified developer and therefore cannot be opened.

You could do it here switch off the gatekeeper of the Mac with terminal commands, but I try to avoid interfering with the security settings of macOS as much as possible and have therefore started looking for other options.

1st possibility: XnConvert - does not work

The first round of googling brought me to a free app called "XnConvert", which can be found in the Mac App Store. The first impressions were also positive: the files were all opened and displayed correctly, but unfortunately something went wrong every time during the export and strange artefacts appeared in some parts of the image.

Even after trying out the settings a lot, the defective parts of the image did not disappear, so that XnConvert can unfortunately not be recommended at this point.

2nd possibility: GraphicConverter - a direct hit

My second idea was "GraphicConverter“ by Lemke Software. A tool that I used more than a decade ago to convert large amounts of images from one format to another. A quick look at the types of files it can import and export, showed me that I was at the right address: GraphicConverter supports WebP both when opening and saving.

So I got the test version, which is fully functional and only differs from the full version in that there is a waiting time when starting the program.

Opening the WebP files went smoothly. All images that were dragged and dropped onto the program icon were immediately displayed in the overview with thumbnails. Since my case was images with transparency, I wanted to choose the PSD format for the output so that layers are preserved for Photoshop.

So that the layers are also saved in Photoshop format, you have to select the PSD format when saving and then select the "Options" button. In the next window, check the “Layers” box.

Small bug: transparent images are reduced to the background level

Unfortunately, there then follows a small bug in GraphicConverter, because even if you have activated the layers in the PSD options, the originally transparent layer is still calculated on a white background in the finished PSD and saved without transparency.

However, I found a workaround that works: You create another layer via the "Layers" menu and the "New layer" menu item, which you drag to the background. The window in which you can change the order of the layers appears via the "Window" menu and the item "Layers visible".

Now you save the file via "File" and "Save as" in the "PSD" format and it works with the transparency channel when you open the image file in Adobe Photoshop.

Conclusion: GraphicConverter is the Swiss Army Knife for image conversion

If you have to convert graphics in different image formats or work with large amounts of files, edit them, add watermarks or convert the resolution, you will enjoy GraphicConverter.

I got the family license for 5 Macs straight away, which only costs EUR 49,95. The full version for a single user costs only EUR 34,95. You can download the trial version of the software Download here at Lemke Software.

If you still have practical tips on working with WebP files on the Mac, I would be happy to hear your comment.

Lynne Marie Kleinholz

With Lynne, a graphic artist and designer has joined the team who contributes articles on the topics of homepage, web development and Photoshop. YouTube has recently become one of her areas of activity. Lynne is (unintentionally) very good at generating error messages and thus ensures a steady influx of problem-solving articles, which repeatedly make the Sir Apfelot blog a popular contact point for Mac users.