The Differences Between Digital Photograph Files

The differences between JPG (Joint Photographic Expert Group), RAW (Camera RAW Sensor Data (Read Unprocessed Data) and TIF (Tagged Image File) saved picture data is the fact that they all provide different types of quality, formatting, and usage.

JPG (Joint Photographic Expert Group) is the most commonly used digital photographic file type because it is easier to use the camera adjustments are saved directly into the JPG file. JPG is the smallest photographic file format and easiest to manipulate. JPG cameras usually offer three groups that enable you to adjust the camera for fine, normal, and basic. I myself always use fine but normal allows the camera to save photographs using less memory space. I do not even use basic it does not look sharp enough for me but it is the least amount photographic quality and smallest JPG file size.

Advantages:

1.      JPG format provides quicker processing

2.      JPG file are compatible with many applications and viewers

3.      Disadvantages:

4.      While zooming JPG relocates boundaries, alters size, shape, and color.

5.      The image is compressed every time it is saved

  

RAW

Most forensic photographers prefer RAW Image Files because they provide the capability of adjustments to parameters that produce high quality photographs.

Advantages:

1.      RAW files are stored in native 12bit grayscale mode 4096 tonal range value which is higher than JPG or TIF.

2.      The computer does all off the processing work and not the camera.

3.      TIF (Tagged image File Format) is the most accurate interpretation of the image and is the most reliable format for forensic analysis.

Disadvantages: 

1.      Large files

2.      Takes longer to print

Crime Scene Photography Edward M. Robinson with Forward by Gerald B. Richards Published by: ELSEVIER Copy right: 2007

http://www.cywarp.com/faq_digital_photo_formats.htm

Camera Auto Focus

I would not use auto focus not unless I absolutely cannot make the camera do what I need it to do. Most of the time auto focus gives you a further away picture than what you desire. I noticed for coverage of bodies that auto focus tends to give you only a focal point of the whole picture which is not good enough for professional photographers. I happen to use a UV screen with a white light to expose all features of the subject I’m photographing. I noticed that the auto focus also adjusts the flash intensity this is something I would rather do manually. It is easier to set the f-stop and make sure the camera is on 50mm with no auto focus that way the camera does not juggle back and forth from 18mm to 55mm or whatever lens setting you have. Some good uses of auto focus on the camera are when you want to take wide area photographs showing lines or photography depth of field. Auto focus seems to work better in large areas with plenty of light such as outdoor verses indoors. Day time photography allows for more light and better composition than night, at night you will have to make manual adjustments to your camera in order to get enough light and zoom close to the object your taking pictures of.  Many mistakes are blamed on auto focus because it is hard to determine what the camera is centering on from a close up view. Other issues are unlevel or unfocused camera action that leads to distorted pictures.

References:

http://www.crime-scene-investigator.net/uvchildphoto.html

http://www.crime-scene-investigator.net/digitalphotography-fried.html

Crime Scene Photography Edward Robinson forward by Gerald B. Richards

Published by Elsevier Press

Photographic Composition 

Photography Composition Is Important

Photographic composition begins with the way you arrange the element and subject matter with in a picture, image composition identifies the visual elements and the subjects with in the photograph.

You must have meaning to a picture our eyes work in a selective manner a picture from far away displays too information at one time for the eyes to look at. Simply centering a photograph is not enough to make the photograph easy to understand.  By applying some techniques you can make a better arrangement for you photographs making them easier to look at and understand what point of view you are displaying in the image.   

There are a number of characteristics that a photographer must take into consideration every time they take a picture most of these include center of interest, Subject matter, simplicity, viewpoint, camera angle balance, shapes and lines, patterns, volume, depth, lighting, texture, tone, contrast, framing ,  foreground, background,  and perspective.  

Each photograph should have only one principle idea. Remember that a photograph is a piece of a large scope every picture should have a dominant center, zooming  in on important elements and taking photographs from different angle allows the viewer the ability to understand what you as the photographer want to display in the photograph.

Capturing the essence of the photograph involves dealing with lighting situations that can improve the overall image quality. Good image quality shows the importance of the photograph to the viewer. Subject placement should allow the photograph to have a balance or flow to it that allows you to center the point of interest of the photograph while keeping lines and dynamic symmetry of thirds within view point.

In specific situations a photographer will have to make alteration to the tilt the camera making it easier to view the top and the side objects in one photograph instead of two. Objects should be displayed in a pleasant view that allows the eyes to quickly identify what the objective of the picture is. Harmonious asymmetrical balance should display, texture, depth and lines without any distractions within the image making the photograph look harmonious and balanced.

Cropping is a technique used to make boarders between other objects to make the photograph more interesting noticing te placement of where the photograph was taken.

As you can see a photographer is able to learn something new with every picture they take.

  

References:

http://photoinf.com/General/KODAK/guidelines_for_better_photographic_composition_balance.html

http://www.forphotography.com/how-tos/compositionplacement.html

http://www.secondpicture.com/tutorials/photography/image_composition.html

http://digital-photography-school.com/5-elements-of-composition-in-photography

http://www.amateursnapper.com/photography/10-top-photography-composition-rules

http://www.geofflawrence.com/photography_tutorial_composition.php

Altering A Crime Scene Photograph

I can only think of several reasons for changing a photograph one is to create a stitch or panorama of a tire track or a foot prints. Another reason to change photographs is to accurately scale the photograph film to make sure it is scaled properly. In both these instances a crime scene investigator would have to use Adobe Photoshop C3 to make the correct changes.

To maintain a fair and accurate depiction of the crime scene you must not change photographs to delete or add items to the photograph that may be misleading. You also need to be able to take photographs that are in the same lighting as the witness sees them. This means that if a witness depicts a crime scene in midday to take photographs that are near midday to depict the crime scene.  A crime scene investigator must always take photographs that are near the accuracy of the size of the actual photograph that they are trying to depict. Other inconsistencies are to accurately depict the size and depth of rooms and hallways photographed by the camera. If these standards are not meet they may disqualify the photographic evidence and have it thrown out of court.

References:

http://www.theiai.org/guidelines/swgit/swgde/swgde_swgit_proficiency_test_document_v1-1.pdf

Criminalistics (An Introduction To Forensic Science) Ninth Edition Author: Richard Safertein Ph.D.  Editor: Pearson Prentice Hall Copyright 2007

Depth of Field

Depth of field allows you to photograph the whole subject matter while keeping the actual focus on the single object. Many photographs will not allow you to take pictures of a single object with distractions in the way moving people, cars, trees, bushes, other photographers, it helps to find a good angle to take photographs from afar while keeping your objective centered. Some of the best pictures use depth of field for objects that either do not fit within regular lens size or need modification to view the whole subject matter. Magnification of the lens plays a big role in focusing  the camera to have depth  of field, another factor of depth of field are the f /stop setting they allow you to view the photograph in the correctly  lighting. Crime Scene investigators should not leave any object out of focus this technique is only used for photographers that take pictures for leisure or sales purposes. All photographs for Crime Scene Investigator must be in focus and directed to the subject matter. 

References:

http://www.cambridgeincolour.com/tutorials/depth-of-field.htm

http://www.photoxels.com/tutorial_dof.html

http://www.photoaxe.com/depth-of-field-photography-tutorial-part-3/

Manipulation of Photographs 

Manipulations are described by adding or deleting details to the photograph. A photograph with the subject centered cannot be edited to delete prudent items from the background. The subject is not to be changed or altered to depict a view of the photograph that was not present when the photograph was first taken. The SOP (Standard Operating Procedure) begins with SWGIT (Scientific Work Group of Imaging Technology) they regulate what changes are acceptable for crime scene investigation photographs that are presented at trial. Manipulations that alter the subject by editing the photograph or deleting items from the photograph that are present in the original copy are not admissible in trail.