Theme 1 – Enthusiasm for revealing hidden details
Users expressed amazement at how the technique brings out faint or invisible markings.
- NDlurker: “Amazing. This will change how I take photos”
- Aboutplants: “Going to be taking a lot more pictures of rock faces!”
- 1shooner: “DStretch is also really great at revealing painted ghost signs on old buildings.”
Theme 2 – Technical guidance and implementation tips
Many commenters shared concrete ways to apply decorrelation stretching in various tools.
- ortusdux: “Matlab - https://www.mathworks.com/help/images/enhance-color-separation-using-decorrelation-stretching.html”
- matja: “The levels tool maps a subset of the channel range to the full range, effectively changing the brightness and contrast in one step.”
- mlmonkey: “Is there an imagemagick implementation that I can just throw into the pipeline?”
Theme 3 – Origins, accessibility, and limitations
Discussion covered the technique’s NASA roots, the difference between the free app and the full plugin, and the long development effort.
- pimlottc: “This is based off a NASA article, which has an expanded version with more details here: https://spinoff.nasa.gov/Manipulating_Satellite_Photos_Now_Reveals_Ancient_Images”
- ButlerianJihad: “A contribution is mandatory before I will send the plugin. … Please note that the plugin is not an app. It has much more functionality than is possible in an app on a smartphone.”
- cwmoore: “In reality very interesting work and results, but a little disturbing that it took three or four decades and a self-funded citizen scientist to transfer the knowledge to the application.”