Practical use of digital photography Working procedure Petr Bendl Jaroslav Tichý Institute of Criminalistics Prague The Czech republic Practical use of digital photography Working procedure Petr Bendl Jaroslav Tichý

Introduction The aim is to determine such working procedure, which enables that the following criteria are met: The aim is to determine such working procedure, which enables that the following criteria are met:  during photographic documentation by a digital camera it is easy to prove image credibility,  credibility shall be easy to prove also during subsequent work with digital image data in further processing and storing,  the possibility of loss, damage or destruction of the data practically excluded. Photography in the shape of digital image data is easily vulnerable and incorrect treatment can lead to their loss, damage or destruction.

Competence of workers making photographic documentation by a digital camera  Education and training in the field of internal regulations setting down the exact procedure of photographic documentation.  Practical ability to carry out individual working procedures used for photographic documentation determined by these internal regulations.  Proper understanding of individual functions and manipulation with cameras and computer technology, through which storing and adjustment of digital image data are made.

Working procedure description Work with digital photographic technology when taking digital pictures Work with digital photographic technology when taking digital pictures A digital camera with accessories must always be stored independently in a camera bag suited for that purpose. In no case can it be stored together with fingerprinting equipment (fingerprint powder, brushes etc.) and other chemical substances and agents used for recovery of evidence at crime scene. A digital camera with accessories must always be stored independently in a camera bag suited for that purpose. In no case can it be stored together with fingerprinting equipment (fingerprint powder, brushes etc.) and other chemical substances and agents used for recovery of evidence at crime scene.

At workplace before going to the scene:  check of functionality of a camera and its accessories,  check of battery, life remaining (a camera set must always spare functional batteries),  check of preset functions of the camera and accessories (mostly in cases where devices are shared by more workers),  check of completeness of the camera set,  check of memory card status (it is advisable that the camera set contains a spare memory card).

At the scene or before taking photographs:  set the quality of images, if necessary – with forensic photo-documentation of crime scene and with taking identification photos (three-part photographs and pictures of special marks and tattoos the size of the image must be at least 5 million pixels),  based on light conditions set the needed sensitivity in ISO,  based on the light source used, make chromatic adaptation through white balance,  make choice and set suitable exposure programme,  check the exposure and correct parameters of a test image, possible re-adjustment of exposure measurement or correction of exposure,  check correct focus,  the photographic documentation itself is carried out in compliance with internal regulations applicable for classic photographic documentation.

Archiving and storing of digital image data files  The person who made the files is always responsible for their archiving (storing).  Upon return to the department, the original file of digital image data is immediately transferred from the memory card or internal memory of the camera to the PC (server), which is used solely for the purposes of archiving digital image files in a directory created before, so that it is possible to retrieve them easily anytime.  If the relevant department does not have a PC (server) for archiving digital image data, then the original file of digital image data is immediately transferred from the memory card or internal memory of the camera to the PC (workstation) in directory created beforehand, so that the data can be easily retrieved anytime.

 Recommended labeling of the directory (always without diacritics!): orig-2004-KUP-AK-0357-TI-hen theft (original digital image file-year-department symbol-record symbol-serial number-author's sign-note)  Check of their flawless transfer is performed.  After the check of transfer the image files are deleted from the memory card or internal memory of the camera.  Original digital image file is backed up on a CD, DVD or another medium, on which the data cannot be deleted, overwritten or additionally adjusted.  The backup is performed twice on physically separated media (two CDs or DVDs).  One such medium will serve as a working backup, the second one as an archive backup. In case the working backup is impossible to read (mechanical damage etc.), a new working backup is made from the archive backup. The original archive backup will than be used as a working one and the newly created one will be used for archiving. Archive backup must not be used for any other purpose.  Archive backup is always stored at the department where the photographic documentation was made.

Working with image data  It is prohibited to tamper with the digital image data in anyway.  It is prohibited to remove any, even poor- quality images (smudged, with wrong exposure etc.) from the original file.  A properly labelled copy is created from the original file of digital image data.  Recommended labelling:  Copy-2004-KUP-AK-0357-TI-hen theft (a digital image file copy-year-department symbol- record symbol-serial number-author's sign-note).

Working with a copy: Working with a copy:  It is prohibited to use any methods, which lead to alteration of the content of the original photographic image or to its optical deformation (local color adjustments, manipulating with depicted objects and texts and other montages).  Adjustments permitted in a copy of the digital image file: - choice and new order of images, - removal of poor-quality images, - supplementing individual images with description, - adjust a selected part, brightness, contrast, colors, sharpen, - adjust its size.

Making photographs from digital image data  Photographs from digital image file are processed in a digital minilab or an analogue minilab with digital exposure unit.  Minilabs are deployed centrally in individual regional administrations and some departments of the Police Presidium.  Digital image files are sent for processing to the minilab: - via official mail on data media (CD, DVD, ZIP etc.), - electronically via computer networks (internal police network etc.).  Photographs from digital image files can exceptionally be processed at the respective department or body, if this is required by the nature of the service (e.g. operational activity, where there impends a danger in delay).

Thank you for your attention.