The feature of the Tondo in the lower left-hand section of the painting is clearly a pentimento, showing an underdrawing of the artist's change of mind in formulating the composition, which has appeared in a ghostly way as the paint has aged. This pentimento can be described as an abbozzo - a rough sketch describing the outline of the composition as originally conceived by the artist.
A monochrome photograph of the painting taken when removed from its frame reveals that the subject-matter of the pentimento is the scarf of the Madonna which sweeps across her shoulders, under her neck and behind the shoulders of the Child. An obvious feature of this scarf is a cross-pattern at regular intervals of two parallel lines and the pentimento clearly shows these lines and in approximately the same regularity. Furthermore, the material of the scarf shows the same twist in its length as appears above the left-hand shoulder of the Madonna. It then sweeps down into a rolled-up ball of material, being the remainder of the length of scarf. The ball of material itself shows the existence of the parallel lines in the pattern. Clearly, the artist decided that the device was inappropriate, because in the finished painting the scarf is brought around in a sweep beneath the Child's hip and thigh.
The existence of pentimenti in a painting is often quoted as evidence for the originality of a work. However, there are reasons why a copyist may also be inclined to make adjustments, for example where they perceive a slight improvement can be made or where the scale of the copy as against the original demands amendments. For this reason, pentimenti cannot be considered as indubitable proof of originality. The essence of a copyist's skill though is how closely his work matches the original, as a photograph reminds us precisely of a specific view, person or group of people. In other words, a copyist has no implied licence to interfere with the original conception other than in a minimal way and one which does not affect the basic format of the original image. Such format would certainly have been fundamentally affected, had the Tondo been painted as the pentimento is drawn.
An X-ray photograph of the Tondo reveals that several alterations in the original drawing have been made to the eye-line of both the Madonna and of the Child. The effect of these pentimenti for the Madonna is to depict a noticeably long nose. Alterations in the drawing of the positions of both mouths can also be observed.