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Deep Zoom Images Adjustable Whole Scan Image Tile Size
Deep Zoom Images

Information in this article applies to:

  • uScope Navigator V4.6 and Later

Article ID: NDZ1315 — Created: 1 Jun 2020 — Reviewed: 17 Nov 2020

Summary

Typically, Whole Scan Images (Deep Zoom, SVS, and SZI) are composed of square image tiles that are 256×256 pixels in size. This size was historically chosen as a best case size for images served from a web site.

Tile Size SettingsuScope Navigator v4.6 adds a Tile Size option under Program Options — Whole Scan Image Options where you may specify the following tile sizes:

  • 256×256 (default),
  • 512×512 (4× fewer tiles),
  • 1,024×1,024 (16× fewer tiles),
  • or 2,048×2,048 (64× fewer tiles).

There are a few trade-offs to consider when changing the tile size from the default.

Advantages of Increasing the Tile Size

  • Process time is reduced. But, not much after increasing tile size to 512×512.
  • Reduced disk space consumption.
  • Disk operations that Copy, Archive, or Move the Deep Zoom folder complete faster.

Disadvantages of Increasing the Tile Size

  • The Deep Zoom image viewer may perform more slowly.
  • Render speed in the Deep Zoom image viewer is decreased. Render lag is apparent with 2,048×2,048 sized tiles.
  • SVS or SZI images may not work in all image viewers. Although, they worked in our limited testing.

Details

A typical problem with Deep Zoom pyramid images is that the number of tiles gets very large (over 1,000,000 tiles) for typical (15mm×15mm) whole slide scans. Copying, archiving (zipping), or moving a Deep Zoom folder can take a very long time when the number of tiles is large. This problem does not exist with SVS or SZI images since they are single-file image formats.

Increasing the tile size, for the most part, offers significant benefits with regards to file operations (copy/move). If you rarely move Deep Zoom images around your computer network, increasing the tile size may not be justified.

Increasing the tile size from 256×256 to...

  • 512×512
    reduces the number of tiles by a factor of four (4). So, a 1,000,000-tile Deep Zoom image is reduced to 250,000 tiles.
  • 1,024×1,024
    reduces the number of tiles by a factor of sixteen (16). So, a 1,000,000-tile Deep Zoom image is reduced to 62,500 tiles.
  • 2,048×2,048
    reduces the number of tiles by a factor of sixty-four (64). So, a 1,000,000-tile Deep Zoom image is reduced to 15,625 tiles.
Notes
  • The Whole Scan Image tile size is used when creating SVS images and SZI images as well as Deep Zoom images. In testing, we found no issues with several SVS image viewers. However, if you experience issues with your viewer, try reducing the tile size to 256×256. If you predominantly use SVS or SZI files, there is little advantage in changing the tile size from the default.
  • In testing, Deep Zoom viewer render artifacts and render lag were both visible with tile sizes of 2,048×2,048. Tile sizes of 512×512 and 1,024×1,024 may prove better for viewing with the Deep Zoom image viewer.

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