Rock Art Enhancer

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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