What Is a THM File, and Can I Delete It?

Video Editor App, KineMaster

What Is a THM File, and Can I Delete It?

Key Points

  • THM files are thumbnail files that store a single image representing and distinguishing videos saved to a camera’s storage.
  • THM files are based on the JPEG standard and can usually be opened in programs that support JPEGs.
  • There are three methods to open THM files: changing the file type in the file name, using a THM file converter, or using image manipulation software like Photoshop.
  • THM files can be saved as PNGs, JPGs, TIFFs, BMPs, and even PDFs.
  • Products like Windows Media Player, iTunes, RealPlayer, and GoPro cameras use THM files to provide visual data and differentiate video files.

If you’ve got a GoPro camera, you might see many mysterious-looking THM files in your camera’s storage. These thumbnail files store a single image representing and distinguishing the videos saved to your camera’s storage. Your GoPro isn’t the only product out there that uses THMs. Let’s examine these files and what they do.

What Is a THM File?

THM can refer to Video Thumbnail Files or Generic Thumbnail Images. These files contain an image representing a video, visually differentiating it from other videos in a storage system. While some people associate THM files with GoPro cameras, seeing as these cameras don’t hide the files from the user, most digital cameras and programs use them to aid user experience.

Typically, a THM will populate with the first frame of the video it represents. Its name will likely be related to the clip it represents. So clip1.avi’s thumbnail will probably be clip1.thm, which makes it easy to determine which images belong to what videos.

The THM standard is based on JPEG’s standard. So, you can usually convince most programs that open JPEGs to open them. However, there are some differences. So, some programs may not support editing THMs natively.

What Do We Use THM Files For?

When using a digital camera, the camera generates and saves THM files for all your videos and photos. These small stills of the original media are displayed in filesystems to help you identify the file. Generally, the original media device generates the THM and shares that file with any devices the video transfers to.

Why Can’t I Open THM Files?

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Capture devices use THM files to aid users in telling their files apart.

Most operating systems’ photo programs can’t natively open THM files. Since you aren’t meant to use these files as standalone media, there’s typically no reason to include exclusive compatibility. However, since the standard is very similar to JPG, you can usually get most THM files to open in programs that support JPGs with a bit of a heavy hand and brute force.

How Can I Open THM Files?

When you scroll through a bunch of media files in a player’s playback list, you’ll typically see small pictures representing the individual files. These images are typically THMs generated using a frame in the video. While most programs generate the THM using the first frame, some may grab a frame from the middle of the film to make the picture stand out more.

You can use three methods to open THM files. However, there is a notable difference in the two methods regarding efficacy. While it is possible to simply turn on the file type in the file name and change the file type to JPG, effectively converting the file to JPG, this type of conversion doesn’t always work as planned. You may experience some strange effects or unusable files when doing this.

Change the File Type in the File Name

To change the file type by renaming the file, you must first allow yourself to view file extensions in File Explorer. Open the File Explorer and navigate to any folder you want. Up at the top of the window, navigate to the View tab. Select “File Extensions” to allow the program to show file extensions in the name.

Once you’ve turned file extensions on, you’ll see that all the files have changed from showing just the name to showing both the name and the extension. Right-click on the THM you want to convert and select “Rename.” Then delete “.thm” and change it to “.jpg” or “.jpeg.”

Using a THM File Converter

You can also use an image file converter compatible with THM files to change the file type to a more usable one. Several THM converters can be found online, where you can upload your files, and they’ll convert them into a cloud for you to download.

This method is generally more reliable than just changing the file extension in the name, as it completely converts the data from the original to the target format. Since a dedicated conversion program converts the file, there is less chance of leftover errors from an incomplete conversion.

We can explain why using a file converter is better than just renaming the file type using a Mark Twain quote:

“How many legs does a dog have?”
“And if I call the tail a leg, how many legs does a dog have?”
“No, it still has four legs. Calling the tail a leg doesn’t make it a leg.”

Simply calling a THM a JPG doesn’t make it a JPG. While the file standards are similar — THM is even based on JPG! — they are not the same. Renaming a file extension doesn’t convert the data; it just forces the computer to read the data as a different type.

Sometimes, this may work out just fine, but that won’t be a universal experience. To change the file type, you have to actually convert the data the file comprises. You can use a genuine conversion program to read the data and change the information to match the new format.

Using an Image Manipulation Software

You can use Photoshop to open and re-save THM files in usable file formats.

You can also open THM files using image manipulation software. Photoshop supports THM files natively, allowing you to open and edit them. You can then save them as the original file type or output them in a different format, allowing them to be used by additional software.

This works similarly to using a file converter. When an image manipulation software like Photoshop outputs a file, it completely reconstructs the image in the target format. Thus, the data it saves is complete and uses all the correct information to read, access, and edit as the target file type.

However, this method also takes the longest. You must open the file in the image manipulator and export it to a different file type. This method requires the computer to reconstruct the image from the THM data completely.

Alternative Formats to View THM Files

THM files can be converted or reconstructed faithfully in almost any image file format. However, it’s worth noting that these images are small. They’re small by design to allow programs to load them quickly. Since they only appear in the playback list, they don’t need to be large. You can save THM files as PNGs, JPGs, TIFFs, BMPs, and even PDFs. Anything that can process and display image data is a free option when converting or re-saving THM files.

What Products Use THM Files?

Several products use THM files. However, most hide these files to provide a cleaner filesystem view. After all, THM files are generally tiny; the space they take up is usually negligible, and deleting them won’t free up any substantial space.

Windows Media Player, iTunes, and RealPlayer are the most common software products that use THM files. They use them to provide distinguishing visual data, allowing users to differentiate between video files stored in the playback features.

GoPro cameras use THMs in their GoPro Quick mobile app. These files are generated by the application which is designed to use them. Essentially, any media device that can store and playback video files likely uses THMs. These files are ubiquitously associated with video files since differentiating them with just names can be hard when using raw footage.

Is It Okay to Delete THM Files?

THM files aren’t necessary to program or hardware function. So, deleting them won’t cause any critical hardware or software issues. However, they will be regenerated when you open the playback list, and they take up virtually no room. So, while you can delete THM files, you don’t usually get anything out of deleting them; they’re not large enough to free up significant space.

Frequently Asked Questions

What is a THM file?

A THM file can refer to either a Video Thumbnail File or a Generic Thumbnail Image. These files contain small-scale images generated from a video’s frames. They represent the media file in playback lists, allowing users to distinguish the file from others in the list.

How are THM files generated?

The original media device usually generates THM files by grabbing a still frame from the video and saving a small version of it as a THM file. Usually, the software will grab the first frame, but some may grab a frame from the middle of the video.

Are THM files large?

THM files are extremely small, both dimensionally and regarding data. The space they take up in a storage device is generally negligible.

Is it okay to delete THM files?

There is no harm in deleting THM files.

Can you convert THM files to other file types?

You can convert THM files to any file format that supports image data.

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