Image Cache

Keep the image browser fast by storing thumbnails, previews, metadata, and histogram data

The image cache helps the Image Browser open folders quickly.

Large photos, raw files, and videos can take noticeable time to read. Instead of reading all of that data every time the folder is shown, the app creates smaller cached files in the background. The Image Browser can then display thumbnails, previews, metadata, and histogram data from the cache.

Source images are not stored in the cache and are not changed by cache maintenance.

What you see in the Image Browser

When you open a folder for the first time, cache files are created in the background. Items appear in the Image Browser when their cache data is ready.

The browser may show different cached data depending on the file type and view:

  1. The thumbnail grid uses small cached thumbnail images.
  2. JPG and TIFF previews use the source image.
  3. Video previews use a cached frame from the video file.
  4. NEF raw previews use the preview JPG embedded in the raw file.

Camera-created raw previews may include in-camera processing such as picture controls, lighting adjustments, or saturation. To see the unprocessed raw data, open the raw file in a raw image editor.

What the cache stores

  1. Thumbnails for the image browser grid.
  2. Preview images for raw files and videos.
  3. Metadata used by the details and metadata views.
  4. Histogram data used by the histogram view.
  5. A placeholder image used while new cache data is being created.

When cache files are created

When you select a folder in the Image Browser, the app checks that folder for supported image and video files. Existing cache files are shown right away. Missing or outdated cache files are added to a background queue and appear as they are finished.

This is why a folder may load immediately even while the numbers at the top of the Image Cache page show work in progress.

Queue status

The status row at the top of the page shows current cache activity.

  1. Priority is the number of high-priority cache items waiting. This is used for work that should appear quickly, such as a newly captured or regenerated image.
  2. Normal is the number of regular folder-scan cache items waiting.
  3. Creating shows the number of active thumbnail creation workers and the maximum worker count.
  4. Cleanup is the number of active cleanup tasks.
  5. The cache size button calculates the current size of the cache folder. Before the size has been calculated, it shows N/A. After you press it, the button caption includes the current cache size.

Max threads used for thumbnail generation

This controls how many background workers can create cache files at the same time.

Higher values can build cache files faster, but they also use more CPU. A good starting point is the number of CPU cores in your computer. If other apps feel slow while thumbnails are being created, lower this value.

Cache data files

Use Explore to open the cache folder in Windows File Explorer.

Use Move to place the cache in a different location, such as a drive with more free space.

Do not add files to the cache folder or edit files inside it. The app may delete and rebuild cache files when you move, clean, reset, or regenerate the cache.

Clean the cache

Clean removes cached files for source image folders that no longer exist or have been moved.

This can reduce storage use. It does not delete source images.

Reset the cache

Reset deletes the current cache folder structure and rebuilds it.

Use Reset when the browser is showing stale thumbnails, previews, or metadata that does not clear after regenerating a folder or thumbnail.

Reset does not delete source images. New cache files are created the next time you open folders in the Image Browser.

Regenerating thumbnails

You can regenerate cache data from the Image Browser by right-clicking a thumbnail or folder and choosing a regenerate command.

Regenerate only the affected items when possible. Reset the full cache only when you want the app to rebuild everything.

Supported files

The cache is used for common photo, raw, and video files supported by the Image Browser, including JPG, JPEG, TIFF, NEF, MOV, and MP4 files.

Troubleshooting

  1. If thumbnails appear slowly, wait for the normal queue to finish.
  2. If a newly captured or regenerated image does not appear, check whether the priority queue is still working.
  3. If the app feels busy while building cache files, reduce the max thread count.
  4. If the cache is taking too much disk space, use Clean first.
  5. If thumbnails or metadata look stale, regenerate the affected thumbnail or folder.
  6. If stale data remains after regeneration, use Reset.