What is DStretch?
DStretch is the name commonly given to decorrelation stretch applied to rock art. It became widely known through the ImageJ plugin created by Jon Harman: it rearranges the colour channels of a photo to exaggerate minimal differences in tone, making visible pigments the eye can barely distinguish.
Is Filtro Rupestre the same as DStretch?
No. Filtro Rupestre is an independent app developed by Collasuyo that applies the same decorrelation principle, with colour modes such as YDS, YBR, YBK, LAB, LDS and LRE. It is not affiliated with DStretch or its author.
Can I use a DStretch-style filter live on the camera?
Yes. Filtro Rupestre applies decorrelation in real time on the phone camera, so you see the enhanced pictograph while framing and can take the photo right then. You can also process photos you already took, in the editor.
Does it work for petroglyphs or only for rock paintings?
Decorrelation mainly brings out pigments, that is, paintings or pictographs. For petroglyphs, which are carvings without colour, the editor includes expert filters such as histogram equalisation, high pass and emboss, which bring out the grooves.
What is the Muro Rupestre?
It is a space inside the app where users share the before and after of their captures and comment on records from the community.
What languages is the app available in?
Filtro Rupestre is available in 11 languages: Spanish, English, Portuguese, French, Italian, German, Russian, Chinese, Japanese, Arabic and Hindi.
How much does it cost and where do I download it?
Filtro Rupestre is downloaded from Google Play. In Chile it costs CLP 4,000; in other countries Google Play shows the price in your own currency.
Original
Decorrelation
