Clematis is a reliably blossoming flower in our garden. Every year we look forward to her blooms for many weeks. Photographing flowers means sacrificing beautiful little things. It took me some time to go there.
With growing experience I feel less pain to sacrifice a bloom for artistic purposes. It relieves me a little, that I have the blooms swum after my photo and X-ray sessions in a soup-plate filled with water which is in the kitchen. Many people like the floating blooms in a soup-plate, if they are in a break.
The HDR series of my composition with three clematis gave me a hard time. Although a tripod is indispensable and always used, a small pixel shift between exposures was perceivable. After fixing this, light, color and structure was processed for an HDR image.
The X-ray of the three clematis was performed as mammography due to the size of my composition. The fusion image can be understood as a texturized HDR by means of a radiograph. But there is no unique solution to all compositions. The best solution has to be found out individually.
After all, the clematis look as light as a feather in this image. It was worth it.
Sometimes reality falls behind our expectations. With 6 red calla lilies I felt well prepared to do some new X-rays and HDR images for image fusion. But my X-ray system surprisingly raised a barrier. The main computer stopped doing his job.
Many thoughts ran through my brain. Will we be able to examine patients the next day ? How fast the supplier will be able to react ? Will the company find a cause of this disturbance ? How many days will my calla lilies be alive ?
I found a work-around by thinking over the interacting hardware. Doing some steps and with a newly restarted system I was able to create 7 different compositions without further disruption of which I show here No. 4.
With X-rays emerges a more impressive illusion of transparency than a plain HDR would have been able to produce. Even when using a lightbox.
Similar to a lightbox it produces better results when laying a petal or a complete blossom over the top of the stalk of another one.
On top of the longest stalk is a twin blossom !
You never know if the inversion in Lab colors leads to an attractive result. It’s always worth looking at Lab color transformations. In this case the black background yields vivid colors.
The shapes and forms are recognizable, yet the level of detail is deeper than the human eye can normally perceive: Leaves appear minutely laced and surfaces are impossibly intricate, somewhere between translucent and opaque. Welcome to the captivating work of photographer Harold Davis and radiologist Dr. Julian Köpke, who combine their skill, passion, and vision to create stunning X-ray photography and pioneering fusion images. Read more on the Pixsy blog (article by Natalie Holmes).
This nice article was posted today to share the fascination of our common work on fusion X-ray images using a light box manual HDR photo of flowers and their X-ray.
Our X-ray data are the same, our photographic data a nearly the same: Harold used a Nikon D850 and I used a Nikon D810A, which is modified for astrophotography. Our common lens was a Zeiss Makro-Planar T* 2/50 ZF.2.
We have some techniques and some principles in common, yet we are different individuals with different results. The next image is partly inspired by Harold’s version. Blue is the complementary color to yellow and fits nicely into the petals. The red color in the center is an image of the sun in monochromatic Hα light using a Fabry-Perot-Interferometer. So this image is a triple fusion image of three different light sources ! If you look closer at 2pm in the center, there are two sunspots.
Different energies of X-ray radiation mean different transparency of an object. There is an example in my FAQ using a Nautilus shell.
Instead of compressing images of different energies to a single image today I subtracted the 70 kV image of a Nautilus shell from the 40 kV image.
The central parts of the Nautilus shell are more dense and show a significant higher difference. The core of the shell gets shiny. This is how it looks like:
In positive X-ray representation you can compare the results. Left hand is the compressed image of 4 different energy levels, right hand the difference image.
Long time ago my friend Harold and I did these X-rays in my practice. There was so much to do. Today was a chance to process the fusion images. Some details can be found in my FAQs.
The manual HDR is already appealing to our eyes.
There is some charm in the X-ray image of the same composition. The hidden parts of the stalks can be clearly seen.
The fusion image of this composition shows both color and hidden structures.
Finished image with a background:
How to show the sun in the middle of a sunflower ? For astronomers it is quite common to look at the sun in hydrogen alpha light, which is a pure red at 635nm. With artistic eyes, a red center might be overdone.
So I tried two different representations, one in BW that is close to the natural look and feel of a sunflower and one with a light blue in the center as complementary color to the yellow petals.
The surface structure of our sun can be seen like astronomers see it.
There is no photo of the next digital X-ray image of a sunflower with its stalk and a leaf:
Long time I dreamed of this fusion image of shells. Because already on a lightbox some of the shells are transparent and have nice colors. I like the shining through effect very much.
The X-ray image is a compromise of structure and density resolution, depending on the maximum energy the mammography system is able to produce.
Today I’m not at all in a stable state due to a recurrent infection. So I allowed me to do this image instead of hard working.
It is the light inversion in Lab color mode that shows more of a X-ray look and feel. The colors are pretty close to the bright image.
In a digital world we can combine different digital sources. This photo of a sunflower is a composit of its X-ray, its photo on a lightbox and monchromatic sunlight at a wavelength of 635nm (Hα light).
In fact: this is an example of an impossible thing. But you may be able to feel the warmth of a sunbeam emerging of the core of the sunflower. And the petals act as prominences.
Are you already high-brow ? You don’t want physics, because you didn’t like it at school ? Then take a look at a well understandable FAQ-sheet for x-rays of flowers given by Harold Davis. The doctor advices you to stop reading here !
Those who like some more background may read the following paragraphs.
Our eyes are sensitive to visible light. The wavelengths of visible light range from 400nm to 750 nm. Digital sensors for photography are modified in their sensitivity to gain a pleasing image for human eyes. E.g. we like green tones. A digital sensor for photography can be modified in its sensitivity within the range of visible light and over a wider range of wavelengths than visible light. The energy of visible light ranges between 1.6 eV (750nm) and 3.2 eV (400nm). Typical spatial resolutions of photographic sensors in the consumer section are between 4µm and 8µm.
A digital x-ray sensor works with spatial resolutions between approximately 70µm and 140µm. Using a medical x-ray machine the available energy levels of x-rays depend on the purpose of a human examination. Energy levels of mammography systems vary between approximately 20 keV and 45 keV, depending on manufacturer. Energy levels of conventional x-rays for bones or chest vary between approximately 80 keV and 125 keV. The corresponding wavelengths are under these conditions 0.06nm (20 keV) down to 0.01 nm (125keV).
As you may know, visible light and x-rays are part of the electromagnetic spectrum. Visible light and x-ray differ in their energy. Higher energy of a radiation means higher frequency and shorter wavelengths. Our eyes don’t see other light than visible light. X-rays are a special light then, not to be seen with our eyes – but with a digital sensor.
A substantial property of x-rays is their ability to run through objects with mainly no interaction. The x-ray sensor „sees“ only a small percentage of less radiation coming from the x-ray source when an object is placed near the sensor.
The left hand image appears normal to your eyes when thinking of an x-ray. Before the digital era, radiologists were using films, an analog medium to produce an x-ray. As x-rays run through an object with mainly no interaction, the dark parts of the left image were fully exposed to radiation. A dark part in an x-ray image therefore was called transparent by radiologists. The parts with lighter grey or white in it were called „opaque“ or „dense“ or „attenuated“ areas. The brighter parts result from the attenuation of radiation by an object. As a matter of convenience, digital x-ray images are shown like the left image. You see already details of the inner structure of our flower, a Bird of Paradise.
The right hand image is an inverted grey scale image. Black turns into white, 50% grey stays unaffected and white turns into black. A 75% grey turns into a 25% white. In every photo editor that’s just a simple and easy action to do. The inverted image is more pleasant to the perceptive habits of our eyes. To our experience, the inverted image is preferable for fusion imaging.
X-ray fusion images
X-ray fusion images are technically composites of digital X-ray images and HDR photos using a commercial digital camera and a light box. HDR photos on a light box already exhibit an illusion of transparency to the observer. Fusion images enhance the illusion of looking through an object.
Image fusion is not limited to flowers. The next example was done with sea creatures on a light box.