It feels like very long ago. Harold and I were taking the shots and X-rays of new compositions last week of April this year. Our first try was an orchid with two stems. The transparency effect is very much augmented using an X-ray. A stem behind petals doesn’t show easily in HDR light box photography.
With a Phase One camera at my disposal a strong crop of the composition shows the tenderness of our orchid much better. With a resolution still sufficient.
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.
First flowers in spring show up. With much support from my colleagues I’m able to do some fusion images. We all would like to have another calendar.
Preparing the lightbox, the X-ray machines, my camera and picking out the data is a bunch of hassle.
My personal favorite is the blue cornflower. It looks like a print of an old botanic book:
The next day I turned my attention to our white and blue Aquilegias. No chance to process the raw data yesterday. Eventually, there was a chance today, after quite a bit of tedious work at my desk:
I assume that everyone has had at some point the experience where less was more. Especially when dealing with computer based image postproduction. Software makes handy wonderful, or better: powerful, filters. Experienced artists know that only a pinch of something or homeopathy is a key to better results.
The same holds true in X-ray production. A maximum of energy does not provide better images. Let’s look closer at this point.
What is the influence of energy to X-ray images ?
Higher energies in X-rays mean shorter wavelengths and a higher resolution. Therefore it might seem reasonable to increase the energy in our X-ray tubes always to the maximum to produce incredible images based on a maximum resolution.
With four images below I show the influence of increased energy levels on X-ray images of a single rose. The applied energy levels are 40kV, 60kV, 90kV and 109kV. The steps of postproduction were the same in every image. Slight differences are owed to best contrast in each exposure.
Surprisingly to the novice we get an increasing loss of contrast (or less available contrast) in each image with higher energies. This effect of loosing contrast can easily be seen in this series of four X-rays and is highest at 109kV.
The explanation for less available contrast with higher energies is the following physical effect: the more photons have shorter wavelengths the more photons run unaffected through the object down onto the sensor. With all photons running through without any hindrance the sensor would show a homogenous gray value.
Every structure looses contrast when turning to higher energies. The optimum for a structure is found by experience and varies significantly.
In the medical field the applied energy strongly depends on the purpose of the examination and the structural demands to be diagnosed.
The above demonstrated meaningless low contrast for our single rose at 109kV doesn’t hold true at all in radiology. Radiologists use frequently 125kV for a chest film to get reproducibly valuable contrast in most patients.
Fusion imaging is beauty made of composite X-ray images and HDR images on a light box. The primary question is what energy fits best for flowers. To my experience 40 kV is often suitable. But: the proof of the pudding is in the eating.
Mammography systems start e.g. from 20 kV and reach 39 kV. The sensor is up to 24cm x 30cm. Conventional systems start from 40 kV and reach 125 kV. The sensor is up to 43cm x 43cm what makes them more attractive to floral compositions.
The higher resolution and the lower energies of a mammography will suit better for transparent objects. But the spatial limit of a composition (which is 24cm x 30cm) might put hard restrictions on the artist.
Floral compositions have more creative space with a bigger sensor. But the X-ray tube starts with 40 kV and this might lead to overexposure of tender structures.
Thus I performed today more than ten compositions to study this relation.
After four exposure of three tulips I found this composition with four dense blossoms attractive to go further. The composition might somehow resemble to a sketch of three angels. The image is nice due to very soft edges of their „wings“, technically blown out portions in the image. The inner structure of the nearly closed blossoms is well resolved. The stalks serve as „body“. There is no advantage with higher energies.
The same composition was done immediately after the X-ray as a bracketing series on a lightbox. After returning I processed a manual HDR, the colors not to warm.
The final fusion image is a composite of the preceding two images. Compared to the lightbox photo, the hidden stalks reappear naturally, the inner petals are outlined like a sketch.
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.
I felt very much attracted by these primroses. They were close to purple and red and I could see them already as a beautiful print.
But how photographing them on a lightbox ? They always toppled over. Many efforts were useless. Blossoms tend to move, always.
On this photograph I put the blossoms top-down. Because any arrangement could be done then. It works !
A different color show the orange primroses. Composition with or without leaves ? Without gives more the impression of a painting.
X-ray images give an insight into the inner (or hidden) structure of a flower. HDR images on a light box are quite close to this.
Today I wanted to show the softness of petals and went to my dealer. She sold me three vetches, not really expensive for the purpose.
This is my third composition today of the three vetches on my lightbox. The play of the light in the petals resembles to some extent X-ray images.
How to prepare a X-ray session ? What flowers suit to a Nautilus shell ? Where does color come in ?
I went to my gorgeous florist to have a look what offer she can make during wintertime. My phantasy were spinning around something ethereal or unrealistic. I bought some flowers with respect to their shape.
The Anthuria caught my eye immediately. The Tulip was still closed and got more and more yellow within hours.
All these compositions shown here were made with dual energy X-ray. The lowest energy of the tube is 40kV, which yields with 4 mAs a quite good insight of flowers. For the center of the Nautilus shell, 70kV and 2.5 mAs is more appropriate.
My first composition was a Nautilus taking off a bouquet of flowers. This reminded me of Renaissance engravings full of symbols. I do not feel depressed. The representation as a X-ray positive jsut shows the bouquet.
A more grounded composition is the second with a Nautilus shell moving towards the roots of my bouquet. Hopefully, the plants will survive. The positive representation always needs some extra editing. By just inverting the Blacks and the Whites the Nautilus would be too dark. Our reception cannot be just inverted and feels alright.
With the look-and-feel of old engravings in mind the third composition ist between surreal and a still. It took me some time to mask out the flaws of an original X-ray to get a true black background. Masking can be done iteratively and easily combined with Photoshop. („That’s what Photoshop is made for !“).
Some colorizing was done to overcome missing photographic shots. There was simply no time in my X-ray unit to do both at a time.
My fourth composition is called „The Argonauts“. The Nautilus shell serves as Argo, the legendary fast ship, with its crew, called Argonauts. The colored version is more convenient for our eyes. As before the X-ray positive looks more ethereal.