Who can use this feature
Editors of a project within a Professional or Pro + workspace.
What is contrast enhancement?
Contrast enhancement is a technique used in image processing to improve the visibility of features in an image. By increasing the difference between light and dark areas, it makes specific elements more distinguishable and details more pronounced. In the context of drone mapping, enhancing contrast in orthomosaics, Digital Surface Models (DSMs), and Digital Terrain Models (DTMs) can help users to better interpret and analyze the geographical data, leading to more accurate and efficient decision-making.
When we display an image on GeoNadir, the software automatically determines the minimum and maximum pixel values within the dataset. The low values will appear dark in the image, while high values will appear bright. But sometimes we are most interested in looking at data values within a very specific range only, not across the whole range that is in the dataset.
For example, in the DSM below over Low Isles, without enhancement we can see the island and the reef, but with little distinction around the reef. When we enhance the contrast in the favour of the lower elevation areas, we can clearly distinguish the tree line, the beach line, and the fine features of the beach rock at the southern side of the island.
How to perform the contrast enhancement
To enhance the contrast of your data, follow these steps:
Click the dataset icon to the left of the dataset name in the table of contents. This will open the style bar. You can also use the keyboard shortcut
'S'to open the style bar relevant to the selected layer.Expand the contrast menu on the style bar.
Use the slider or enter minimum and maximum display values for individual layers (orthomosaic (RGB or Greenness index), DSM, DTM).
Use the reset icon to return to the original contrast stretch.
OR
Select the dataset
Click the toolbox icon on the top menu bar
Go to enhancements
Go to Enhance contrast
Use the slider or enter minimum and maximum display values for individual layers (orthomosaic (RGB or Greenness index), DSM, DTM).
Use the reset icon to return to the original contrast stretch.
To learn more about contrast enhancement, please check out our blog!