Rock Art Enhancer

BinaryEarth

About this app

This app uses advanced techniques to enhance the colours in rock art to make faint drawings and stencils more visible. Techniques used include decorrelation stretching, histogram equalization, saturation enhancement, and hue/brightness matching. It works on photos from your phone's gallery and also has a live video enhancement mode. Enhanced photos can be saved for later viewing and sharing.

The live enhancement mode lets you hold your phone over a possible site of rock art and enhances the colours in real time to help you see what's there. In this mode, you can short press the screen to cycle between the different enhancement techniques, or long press to toggle the flash on/off to make it easier to view art in dark rock shelters.

The auto photo enhancement mode lets you choose a photo from your phone's gallery and carries out the same enhancements as available in the live mode. Short pressing the image opens it in your phone's photo viewing app.

The manual photo enhancement mode lets you choose a photo from your phone's gallery and has a drop down to choose the hue you want to enhance (e.g. red). This sets the default positions for the hue and value sliders (in HSV colour space). When you press the apply button, the pixels in the image matching the slider ranges are changed to the selected colour. To revert the image, choose a match colour of "None". Short pressing the image opens it in your phone's photo viewing app. Long pressing on the image will bring up a pixel chooser which lets you select a custom hue for colour matching.

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Ratings and reviews

Nice, easy to use implementation and the update to 2.2 solved the irritant of Android 11's restrictive policy of accessing the saved image folder. Extremely good value app this! One thing - live mode: it takes a lot of taps to cycle through all the colour spaces and adjustments; in a site, if two enhancements work well, it is unhelpful not to be able to select them directly to alternate the view. Semi-transparent buttons along the bottom, perhaps?

Very specific use, but a handy tool for those interested. Developer responded to my email for suggestion immediately, and issued an update after only a few hours

Enjoying the app, would've rated 5 stars if not for one seriously important problem. It does not save the pictures post enhancements, can't find them anywhere on the phone. Need help rectifying.

What's new

3.0: Updated to target Android SDK 34.
2.9: Updated to target Android SDK 33.
2.8: Added check box on main photo enhancement page to toggle on/off enhancement.
2.7: Added button to take photo from app. Allow photo rotation of 0, 90, 180, or 270 degrees.
2.6: Added an option to save photos to your phone's gallery, instead of to the app's private data storage. Significantly improved performance of YUV and Lab Custom modes.
2.5: Added "D.Stretch Lab Custom" enhancement mode.