Digital image enhancement with DStretch®: Is complexity always necessary for efficiency?

• We argue that using DStretch® greatly facilitates the recording rock-art in remote areas and harsh environments.
• We propose a two-step procedure for on-site documentation.
• Our tests show that digital enhancing does not preclude subjectivity, as final tracings are always subjective and biased by personal perceptions.
• A code of good practice should be installed in this field.

DStretch®, plug-in for ImageJ© is designed specifically for the enhancement of digital images of pictographs. It is now widely used in the world since a decade but have thus far rarely been used in French and African rock art studies. Among all the software tools currently available to rock art specialists, it is one of the most efficient to decipher faint paintings and sometimes engravings, while being cheap, fast and easy to use, particularly in harsh or remote environments. Moreover, the enhancement of digital images with DStretch® is almost operator-independent and reproducible thanks to pre-recorded settings, thus improving objectivity. We provide several examples of the benefit of using this tool on various sites, from African prehistoric pictographs to Alpine paintings and petroglyphs, and propose a method for recording rock art panels with DStretch®. But, in spite of these advantages, we have to keep in mind that the final tracings are always subjective and biased by personal perceptions, as demonstrated here by a simple but significant experience.