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Image Enhancements

The Image Enhancements panel adjusts how imagery looks in the annotation view. Open it from the context sidebar (Web) or the viewer controls (Desktop).

Settings are saved per dataset in the imageEnhancements metadata field and restored the next time you open the dataset.

Standard controls

These apply to 8-bit and tiled imagery on both Web and Desktop:

  • Brightness — linear intensity offset
  • Contrast — linear intensity scale around mid-gray
  • Saturation — color saturation (meaningful for RGB imagery)
  • Sharpness — convolution sharpening filter

They are applied as SVG filters on top of the displayed image or tile layer.

Use Reset to return all sliders (including percentile stretch) to defaults.

Percentile stretch (greater than 8-bit)

High bit-depth sources such as 16-bit TIFF are often imported or transcoded into a narrow 8-bit range for display. Percentile stretch remaps pixel values using histogram percentiles so detail is visible without permanently rewriting the source file.

When supported, the panel shows:

  • A Percentile Stretch toggle
  • A histogram of the current frame (when available)
  • Low % and High % sliders (defaults 1 and 99) that clip the dimmest and brightest portions of the histogram before stretching to display range

Low and high cutoff markers on the histogram update as you move the sliders.

Where percentile stretch is available

Dataset type Platform How stretch is applied
large-image (TIFF / GeoTIFF) Web Girder large_image tile style parameters; histogram from item/{id}/tiles/histogram
image-sequence (TIFF originals) Desktop On-demand PNG from the original TIFF via the local /api/media/display endpoint
image-sequence (TIFF) Web Not available — import-time transcoding produces 8-bit PNGs
8-bit PNG / JPEG / video Web or Desktop Percentile stretch hidden; use brightness/contrast only

For Web high bit-depth TIFFs, import the file as a tiled large-image dataset (see Large Image Support) rather than as a folder of PNGs. The viewer uses LargeImageAnnotator and Girder tile endpoints for display and stretch.

For Desktop folder-based TIFF sequences, DIVE keeps the original TIFF on disk and serves stretched frames from that source while annotations continue to reference the transcoded PNG timeline.

Pre-scaling vs dynamic stretch

Large Image Support documents optional GDAL pre-scaling to 8-bit COG (gdal_translate … -scale <min> <max> 0 255). That produces a fixed display range at import time.

Percentile stretch is an interactive alternative (Web large-image and Desktop image-sequence TIFF): you can tune low/high percentiles while annotating without re-exporting the file. Pre-scaled COGs and percentile stretch can both be valid depending on workflow.