In conservation-restoration, visual documentation is an essential part of any intervention. Photographing a work before, during, and after treatment allows for recording its condition, comparing changes, and justifying decisions made. However, in many cases, the image does not just serve to illustrate a process: it can also become a source of data.
As part of my final degree project, focused on the study of enzymatic systems applied to the cleaning of acrylic surfaces, the ImageJ program was used as a complementary tool to analyze images of samples before and after treatment. The objective was to more objectively assess the visible changes produced in wax stains applied to acrylic paint.
What is ImageJ?
ImageJ is a free image analysis program widely used in scientific contexts. Its operation is based on the measurement and processing of digital images, allowing for outlining areas, calculating surfaces, comparing variations, and obtaining quantifiable data from a photograph.
In this study, the program allowed selecting the areas corresponding to the wax deposits and comparing their evolution after the application of the gelled enzymatic systems. In this way, visual observation could be complemented with a more precise reading of the changes produced in each sample.
How it works: from photo to measurement
The work process starts with good photographic documentation. For comparable results, images must be taken under similar conditions of lighting, distance, framing, and scale. Once the image is opened in ImageJ, the scale can be calibrated, the area of interest delimited, and the selected area measured. This data allows for comparing the initial surface area of the stain with its state after treatment.
It is important to keep in mind what exactly the tool measures: ImageJ quantifies the surface (area) of the stain in the image plane, not its thickness or mass. A deposit can thin or fragment without its area changing proportionally, so the surface measurement is a valuable indicator, but it must be interpreted together with direct observation.
Why it is of interest in conservation-restoration
One of the main benefits of ImageJ is that it helps reduce subjectivity in the evaluation of results. Instead of simply stating that a stain has decreased or that a deposit has fragmented, the program allows for supporting that observation with measurable data. This is especially useful in experimental trials, where it is necessary to compare samples, action times, or different cleaning systems.
Even so, ImageJ does not replace the conservator-restorer's judgment. The interpretation of the results still depends on direct observation, knowledge of materials, and evaluation of the surface condition. The program should be understood as a complementary tool, not an automatic answer.
Its interest for conservation-restoration lies precisely in its ability to combine image, measurement, and documentation. In cleaning treatments, alteration studies, stain analysis, monitoring of lacunae, or evaluation of surface changes, ImageJ can provide a simple and accessible way to record visual information more rigorously.
In short, the use of ImageJ allows a photograph to be transformed into an analysis document. It not only shows what has happened during a treatment, but it helps to measure it, compare it, and explain it better. For a discipline where every decision must be justified, this possibility is a particularly valuable tool.
This article is complementary to Enzymatic cleaning of acrylic paint: lipase and gels, which describes the study from which these images originate.
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