Pentimenti are 'ghost-like' images visible in areas of an oil painting that had been painted over by the artist, when he or she decided to move elements of the composition, and which gradually reappear. These images, which may range from a barely noticeable coat hem to a full figure, are usually invisible to the naked eye when the painting is completed. They are sometimes visible in raking light, however, as the paint surface becomes more transparent with age. Pentimenti show the natural progression of changes and corrections that an artist typically makes while creating a painting. There are several signs that pentimenti are present. For example, the top paint layer may have cracked and revealed a different color paint below. Or there may be an impasto ridge that does not correspond with the design of the finished brushwork. A shadowy image may be visible that does not make sense as part of the rest of the painting or duplicates an existing element in a different position. Radiographic analysis of a painting will reveal more of the overall image and artist's changes than what is usually discernible to the naked eye and can provide further information about the artist's creative process. However they are detected, pentimenti do not necessarily detract from a painting. They can also be helpful to scholars, because they reveal the artist's thought process and techniques as he evolves toward the final composition and can, therefore, help to verify the authenticity of a painting. Forgeries, of course, most likely would not show such subtle artistic changes and progressions. Conversely, the absence of pentimenti does not mean that the painting is not an original. A painting does not have to be old to exhibit pentimenti, as many modern paintings also show artists' changes that have become visible over time. When conserving paintings with pentimenti, conservators in concert with their clients need to decide how much intervention or “tweaking” is required to present the painting in as close to the final state intended by the artist as possible. If minor pentimenti, such as earlier versions of a coat hem or a flower, are selectively mitigated, one needs to document the process and ensure its reversibility. If, however, the pentimenti are too dense and extensive to be easily camouflaged, then they should be left untouched as too much repainting would be necessary which would compromise both the integrity of the artwork and its value. In all cases, Lowy's conservators favor the least invasive approach, following the same guidelines for pentimenti as for condition pitfalls such as tears, cracks, flaking and other structural losses.