Scholarly record

CREATING HDR PHOTO BY MANIPULATING DYNAMIC RANGE OF A SINGLE RAW FORMAT PHOTO

Dubravka Maurer, Dr. Sanja Samanovic, Assist. Prof. Dr. Dubravko Gajski

Abstract

Contemporary digital cameras enable automated process of creating several photos of the same frame in different exposure (bracketing). By the post processing of the photo, editing it in tone mapping, correctly illuminated parts of individual photos are merged into a new one - High Dynamic Range (HDR) image. The differences between illumination of the parts of the object in direct sunlight and the one in deep shade result in a lack of recognizable details which creates challenges in photogrammetric interpretation. The dynamic range of photo stored in RAW-format reflects the abilities of the sensor to record the intensities of light. Contemporary software packages allow manipulation in the range of illumination to create five photos with different exposure values (-1, -0.5, 0, +0.5, +1) from the single original RAW format. Photos were then merged into one HDR image with uniform illumination in all frame (subject/pattern) without any loss of quality. This method of creating pronounced real textures of the subject enables quality photo interpretation and the creation of orthophoto with significant application in 3D modeling in architecture and cultural heritage. It is also exceptionally practical in creating HDR images from photos taken by drones where there are no possibilities of taking more photos from the same observation point.

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