When we start a process of image acquisition, the goal is to have a single frame that covers the whole subject, and this result depends in general on the type of lens/objective used. It may happen however that the subject has a large size, it is then necessary to acquire individual sections to create a mosaic covering the entire area of interest. This technique is often used when you want to obtain images in which there is the need to maintain the finest detail possible or print photos in very big formats.
In the example that I show you on this page, I want to frame an Elaterid beetle and a spider in a single scene; it was therefore necessary to acquire two stacks (composed of 96 images each) to cover both subjects.
When you create a mosaic, it is important to have a good degree of overlap between images, this helps the algorithm to find the same morphology/geometry in the adjacent photos, and to create a seamless transition between photos. In general, it is good to have an overlap of not less than 30%-40%.
The procedure described is based on the use of Adobe Photoshop (an old version, but that does its job), but there is a lot of open-source software allowing to perform similar operations, with good results. You can have a look at the Microsoft Image Composite Editor that works very well. Unfortunately, it seems that this software isn’t available anymore, but you can download a recent Windows 64-bit release (v.2.0.3) from here, or try different software from here.
The interesting thing about PS (and Camera Raw add-in) is that it can import the .dng format (16bit) created in output by Helicon Focus software, keeping the color levels and metadata.
After having imported the images into the Adobe platform, let’s start to create a new intermediate stack where the common parts will be roughly overlapped. This operation is launched from the menu File > Scripts > Load Files into Stack… In correspondence with the Load Layer window, select the two images (click on “Add open Files“) and check the option “Attempt to Automatically Align Source Images“.
If the two images are not perfectly overlapped, or if the process fails to find the correspondence, don’t worry, sursum corda!, you can always move them manually to have a more or less correct overlap and go to the next step. Obviously, the better the images are overlapped, the better the result will be.
After this first step, select from the Tab “Layers” the two layers (shift-click) and from the Edit menu the option “Auto Blend Layers…“. The window that appears asks you to select the option Panorama or Stack Images. Select the Panorama option, check the “Seamless Tones and Colors” option to have a greater homogenization of colors in the overlapped areas, and confirm.
Photoshop allows you to create, in a similar way as Helicon Focus or Zerene Stacker software, image stacks, but with the small defect that it is EXTREMELY slow. It can work with stacks composed of a few tens of images, but for stacks that require the use of hundreds of frames, it is impossible to use, you risk seeing your kids become older. Also, the results obtained sometimes leave a little to be desired.
Back now to the analysis. The result obtained launching the Panorama option, is an image in which you can see the presence of a tiny white irregular line crossing the middle part of the photocomposition. The PS algorithm searches for areas that are geometrically and radiometrically similar, creating a mask in the adjacent photo and vice versa.
Hiding an image from the Layers Tab clearly shows how the search for similar adjacent areas worked.
At this point, you just need to merge the two layers into a single image (Control-E, with the two layers selected) to get the result, and you are ready to make all color adjustments and apply the necessary filters for the final rendering.
Creating a big mosaic 1/2
Behind the Image – Photographing Ammonites in Burmese Amber
The most challenging part is when you have a large sample to mosaic. In the following example, there is a 6.5 × 5 cm piece of amber containing numerous inclusions that are interesting to photograph. I’m using a Schneider Componon 50mm f/2.8 reversed lens, which provides excellent results and covers a relatively wide area. The lighting system consists of two 20W LED panels carefully oriented to ensure uniform illumination over the sample, which is immersed in glycerol, as shown in the following image.
To cover the entire specimen, 29 stacks were required, each composed of approximately 30 individual frames, resulting in a total of 834 shots. The images are processed in Helicon Focus Pro (v.8.3.1), exported in .DNG format, and then imported into Adobe Photoshop. The 29 tiles are arranged on the workspace to check whether the entire area is correctly covered. The XY movement is done manually with a good overlap between each tile (~20%), but occasional errors may occur. Therefore, this validation step is crucial to avoid unwanted gaps in the final result.
Once the first validation is complete, the next step is to properly align the tiles. In Adobe Photoshop, I use the Photomerge tool with the simplest option, “Reposition,” but I uncheck “Blend Images Together.” I prefer to manually adjust the automatically positioned tiles to fine-tune the overlap, which is generally very accurate.
The alignment process requires patience and depends on the processing power of your computer. The result is a mosaic composed of correctly overlapped tiles. When necessary, the tiles can be selected using the CTRL + Click shortcut and adjusted for better alignment. The next step is to run the Auto-Blend Layers tool (as described in the previous paragraph) to seamlessly merge all the layers, following the geometry and harmonizing the colors between tiles. The final result is a complete mosaic with properly merged tiles.
After merging the entire mosaic into a single image, I adjust the color levels and reduce noise to enhance the visibility of details. The outer edges of the amber are cleaned, and a uniform background color is added. The final image is saved as a .jpg with dimensions of 26,467 × 34,938 pixels and a file size of 60.4 MB (low compression to preserve details). The raw dataset, in .psb format, occupies 3.04 GB.
Below the final result and in the slide show some print-screen. Yes, there is also a section of a ammonite! Can you see it?
Creating a big mosaic 2/2
Behind the Image – Photographing a Giant Termite in Burmese Amber
In this post I’d like to take you behind the scenes and show the complete workflow I normally follow when photographing a particularly large inclusion.
The specimen is an impressive termite preserved in Burmese amber. I believe it is the largest insect I have ever photographed.
Before anything else, I would like to publicly thank Har Nit, a young dealer from Myanmar who supplied this remarkable specimen. Despite the many challenges created by the current political situation in his country, he continues to work with great determination and professionalism. I sincerely wish him every success.
The amber itself measures 3.5 × 3 × 1 cm and has a deep orange-brown colour. Unfortunately, it also contains several opaque layers that make observing the insect much more difficult. The first photograph shows the impressive size of the specimen.
Step 1 – Finding the best viewpoint
The first and probably most important step is to examine the amber under a stereomicroscope.
This allows me to determine the most “photogenic” orientation of the inclusion. Even rotating the amber by only a few degrees can completely change the visibility of important anatomical details. Without a stereomicroscope, these subtle differences would be almost impossible to detect.
Step 2 – Preparing the specimen
Once the best position has been identified, the amber is fixed inside a Petri dish.
Depending on the specimen, I use either UHU Patafix or, as in this case, double-sided adhesive tape. The tape allows the entire piece of amber to remain visible without any part being hidden by the mounting material.
As described in a precedent page, the amber is then completely immersed in glycerol, which greatly improves optical quality by reducing surface reflections.
One small but essential detail is the removal of air bubbles. They almost always appear somewhere on or beneath the amber and must be carefully removed with a fine needle before photography begins.
Step 3 – Lighting
For this specimen I chose a brightfield illumination setup.
A LED panel positioned beneath the Petri dish provides strong transmitted light, which greatly enhances the contrast of the termite against the surrounding amber.
Two additional 20 W LED panels illuminate the specimen from above. These lights are always used with diffusers because direct illumination would generate unwanted reflections inside the amber and greatly reduce image quality.
Left: lighting from the above with the Smallrig led panel / Right: lighting with the 2 20W LED panels
This particular piece contains numerous internal fractures, making careful light control especially important.
In this particular case, to enhance the contrast of the Termite, I used a brightfield setup, utilising a Smallrig LED panel (https://www.smallrig.com/eu/SmallRig-P96-Video-LED-Light-3286b.html?sku=3286BC) which is particularly effective for this purpose. The same company offers, amongst its many photography tools, an articulated arm (https://www.smallrig.com/eu/Desktop-Shooting-Magic-Arm-with-Crab-Clamp-Kit-4766.html?sku=4766), which is very useful for this purpose.
Note: I mention the SmallRig equipment simply because it works well for my setup. I have no commercial relationship with the company, and many equivalent products are available from other manufacturers.
Step 4 – Choosing the lens
The lens must be selected according to both the size of the inclusion and the level of detail required.
For this photograph I used a reversed Schneider Kreuznach Componon-S 50 mm f/2.8, a lens that delivers excellent optical quality for extreme macro photography.
However, its field of view is too small to capture the entire amber in a single photograph.
The solution is to divide the specimen into multiple overlapping sections that can later be combined into one large mosaic.
Step 5 – Capturing the images
The amber was divided into eight overlapping sectors.
Each sector required approximately 60 photographs taken at different focus distances in order to keep the entire depth of the inclusion perfectly sharp.
In total, I captured 435 individual photographs.
Step 6 – Focus stacking
Each series of photographs was processed using Helicon Focus, although excellent alternatives include Zerene Stacker and the open-source Shine Stacker, developed by my friend Luca Lista.
Using a technique known as sub-stacking (also called slabbing), the original 435 photographs were reduced to 143 intermediate images, making the subsequent retouching considerably faster and more efficient.
Step 7 – Building the final mosaic
The eight final stacks were exported as 16-bit DNG files and imported into Adobe Photoshop.
Using Photoshop’s Photomerge function, the eight sectors were automatically aligned and blended into a single image.
To be honest, this step always feels a bit like magic.
With this particular lens, barrel distortion can sometimes make mosaics extremely difficult to assemble, so obtaining such a clean result was a pleasant surprise.
Step 8 – Final adjustments
The last stage consists of colour correction, contrast adjustment, noise reduction and selective sharpening.
Unfortunately, while reviewing the final image, I discovered a small air bubble that had either escaped my attention or moved beneath the amber during photography. Removing it digitally isn’t particularly difficult—it simply requires a little patience.
How long did everything take?
From placing the specimen into the Petri dish to exporting the final Photoshop and JPEG files, the entire process required approximately three hours.
The finished mosaic contains enough detail to be printed at approximately 130 × 150 cm while maintaining a resolution of 300 dpi.
Thank you for reading all the way to the end!
If you’ve made it this far, you’ve probably joined the small percentage of people who enjoy discovering not only the final photograph, but also everything that happens behind the camera.
For me, photographing amber is much more than pressing the shutter. It is a combination of science, patience, problem-solving and, occasionally, a little bit of luck.
Happy Stacking!
Enrico Bonino — Extreme Macro Photography and Paleontology 