cranium and mandible imaging protocol: a guide for...

CRANIUM AND MANDIBLE IMAGING PROTOCOL: A GUIDE FOR PUBLICATION-QUALITY DIGITAL PHOTOGRAPHY OF THE SKULL PROTOCOLO PARA IMAGENES DE CRÁNEO Y MANDÍBULA: UNA GUÍA PARA PUBLICACIÓN DE FOTOGRAFÍA DIGITAL CON ALTA CALIDAD

KELSIE HART UNIVERSITY OF CALIFORNIA, BERKELEY SOCORRO BÁEZ-MOLGADO HUMAN EVOLUTION RESEARCH CENTER, UNIVERSITY OF CALIFORNIA, BERKELEY

FOROST Occasional Publications • No. 2 • August 2013

FOROST Occasional Publications

Materials

1. Choose a camera and accessories

DSLR camera with resolution of over three megapixels

55 mm lens with an aperture that can be tightened to at least f16

Live computer interface

Back-up system for image storage

Photo editing software (such as Adobe Photoshop™)

Camera copy stand

Tripod

2. Camera and copy stand setup

3. Cranium setup

Specimen safety

Be aware of specimen at all times

Always wear gloves

Never place specimen directly on a hard surface- use cushions or foam

Never leave specimen unattended

Place all objects at a safe distance

Secure cords with tape

Don’t use metal rulers for alignments

4. Alignment of cranium

Frankfurt Horizontal (right and left porion and left orbitale)

Approximate alignment of mastoid processes

Approximate alignment of sagittal plane

Courtesy of the Phoebe A. Hearst museum of Anthropology and the Regents of the University of California. Photography by the FOROST Development Team, (Catalogue No. 12-10250).

4.1 Anterior view of cranium

Courtesy of the Phoebe A. Hearst museum of Anthropology and the Regents of the University of California. Photography by the FOROST Development Team, (Catalogue No. 12-10250).

4.2 Basilar / Inferior view of cranium

Courtesy of the Phoebe A. Hearst museum of Anthropology and the Regents of the University of California. Photography by the FOROST Development Team, (Catalogue No. 12-10250).

4.3 Left lateral view of cranium

Courtesy of the Phoebe A. Hearst museum of Anthropology and the Regents of the University of California. Photography by the FOROST Development Team, (Catalogue No. 12-10250).

4.4 Right lateral view of cranium

Courtesy of the Phoebe A. Hearst museum of Anthropology and the Regents of the University of California. Photography by the FOROST Development Team, (Catalogue No. 12-10250).

4.5 Superior view of cranium

Courtesy of the Phoebe A. Hearst museum of Anthropology and the Regents of the University of California. Photography by the FOROST Development Team, (Catalogue No. 12-10250).

4.6 Posterior view of cranium (use tripod)

Camera and tripod setup

4.6 Posterior view of cranium (use tripod)

Courtesy of the Phoebe A. Hearst museum of Anthropology and the Regents of the University of California. Photography by the FOROST Development Team, (Catalogue No. 12-10250).

Photography of the Mandible

Courtesy of the Phoebe A. Hearst museum of Anthropology and the Regents of the University of California. Photography by the FOROST Development Team, (Catalogue No. 12-10250).

Anterior view of mandible

Left and right lateral views of mandible

Superior view of mandible (use camera copy stand)

5. Lighting setup

Most important and time-consuming step

Many different ways to achieve proper lighting

Need to experiment and take many test photographs- in conjunction with camera settings

Goal: indirect, oblique illumination from all directions- show topography while minimizing heavy shadows

Sample lighting method

6. Adjust the camera settings

Conditions: still photography, large depth of field, low-light, stabilized DSLR camera

First: 55 mm lens, manual mode, no flash, 10 second timer

The ‘exposure triangle’:

Aperture / f-stop

ISO

Shutter speed

6.1 Aperture / f-stop

Mechanically controls the size of the aperture (iris) and thus the depth of field

For cranial photography, we need a large depth of field

A high f-stop will shrink the iris and enlarge the depth of field

A high f-stop can cause distortion

55 mm lens at 1.2 m and f 16 is recommended and should not cause distortion

6.2 ISO

Controls the camera’s sensitivity to light

High ISO increases sensitivity to light but can cause image to be grainy

Use camera’s optimal ISO and adjust the exposure using the shutter speed

6.3 Shutter speed

Controls the duration of exposure

Because we use a stabilized camera and low-light conditions, a long exposure (slow shutter speed) can be used

Any vibration of the camera will cause distortion

Use copy stand / tripod and 10 second timer

7. Check the camera for a final look at the image

The cranium should be centered in the camera frame and properly aligned

The black velvet should lie smoothly and the scale should not touch the sides of the cranium.

The scale and cranium should be fully visible, in focus, and well-lit.

8. Take the photograph using a 10 second timer

9. Review the photograph (on the computer)

Make sure the cranium is well-lit everywhere and in focus

The cranial features should be visible in sharp detail when viewed at a zoom value of 100% (where each screen pixel equal one image pixel).

If necessary, make adjustments and retake the photo.

Label the image according to a desired naming protocol.

When saving the file, do not use the JPEG format or compress the TIFF.

10. Edit the photo (optional)

Brightness, contrast, and other non-distorting filters are acceptable

The scale can be straightened or replaced with a digital scale rendered in the same proportions.

The background, except for a small margin around the cranium itself, can be replaced with solid black

Unedited Photo (left lateral view)

Courtesy of the Phoebe A. Hearst museum of Anthropology and the Regents of the University of California. Photography by the FOROST Development Team, (Catalogue No. 12-10250).

Left lateral view after editing in PhotoshopTM

Courtesy of the Phoebe A. Hearst museum of Anthropology and the Regents of the University of California. Photography by the FOROST Development Team, (Catalogue No. 12-10250).

Courtesy of the Phoebe A. Hearst museum of Anthropology and the Regents of the University of California. Photography by the FOROST Development Team, (Catalogue No. 12-10250).

Courtesy of the Phoebe A. Hearst museum of Anthropology and the Regents of the University of California. Photography by the FOROST Development Team, (Catalogue No. 12-10250).

Acknowledgements

Erika Najarro University of Washington

Dr. Sabrina B. Sholts Stockholm University, Sweden

Dr. W. Henry Gilbert California State University, East Bay; Human Evolution Research Center, University of California, Berkeley

Dr. Carlos Serrano, IIA, and UNAM

Phoebe A. Hearst Museum of Anthropology , UC Berkeley

Human Evolution Research Center, UC Berkeley