Julian Köpke

How to communicate an erratic process in terms of an image ? The Iliadic greek were pirates of the Mediterranean with fast vessels, invading mainland from the seas, enslaving people, robbing stocks and much more.

The writing down of the Ilias was between 678 and 662 B.C., a time of Assyrian dominance and cultural superiority.

With three different Nautilus shells I bought last September on Crete I did this composition on my big X-ray sensor with 35cm x 43 cm and 170µm per pixel resolution. Two energy levels were necessary to get a high resolution image of the core of the Nautilus shells.

To overcome the look-and-feel of a medical X-ray it is a logical idea to invert the light. Black becomes white and vice versa. White means shining through of X-rays, black means opacity. It’s like a dream !

You always need some time to find out the best exposure values for a photo. Same idea holds in X-Ray imaging.

Today I did an x-ray series with my biggest Nautilus shell on a conventional radiography sensor, not a film. Starting from the lowest possible value 40kV an increment of 10 kV up to 70 kV can be seen in the images:

Black regions in the image a transparent, white are opaque. The center of the Nautilus has a loss of structure.

With 50 kV the structure in the center of the Nautilus is better depicted wheras the edge gets more transparent:

Same effect for the center and the edge can be seen with 60 kV:

With 70 kV it’s an exaggeration for the edge and best depiction for the center:

Higher kV means more transparency for denser structures but a loss of structure in transparent areas.

At fixed energy, X-Ray imaging behaves like a shadow related to visible light. When photographing, there is not chance to look through an opaque object. With higher energies, x-rays go through opaque objects and can be collected on a sensor.

Composing the images obtained at different energies is an X-Ray HDR image:

The representation of an X-Ray with white on black is a reminiscence of the film era. Radiologists just looked at the negatives ! Inverting black and white shows the positive image, like a print. Here I show the same image as positive, but rotated and flipped horizontally. Look how ethereal it appears now:

X-ray Odyssey

Transparency and Energy in X-Rays