Summary Findings for the Five Test Paintings

(1) (2) (3) (4) (5)
A. Does the painting show "optical" features not seen in normal paintings?
B. Could an artist have produced these features by tracing a projected image?
C. Has this "tracing" explanation for the "optical" features been disproved?
D. Can other explanations account for the "optical" features?
E. Has an artist produced these features by tracing a projected image?

* The paintings are numbered: (1). Lotto Husband and wife; (2). van Eyck Cardinal Albergati; (3). van Eyck Arnolfini Marriage Portrait; (4). Caravaggio Supper at Emmaus; (5). Vermeer Music Lesson

Specific findings for the five test paintings

A. What are the "optical" features? *

  1. The carpet is partly blurred. Perspective lines do not converge to a single point.
  2. The sketch and the final painting are astonishingly similar.
  3. The chandelier is shown in remarkable detail but from the wrong viewpoint.
  4. The perspective is distorted.
  5. The painting has a photographic look with unreal optical highlights.

SUMMARY: None of these features are to be found in traditional representational paintings of the same period.

B. How could these features have been produced by tracing a projected image? *

  1. By tracing the projected image in sections, refocusing when the image is moved
  2. By tracing a image of the sketch projected onto the surface of the painting
  3. By tracing a image of the chandelier projected onto the surface of the painting
  4. By tracing the projected image in sections, refocusing when the image is moved
  5. The painting has a photographic look with unreal optical highlights.

SUMMARY: All of the features can be generated as a consequence of tracing a projected image.

C. Has the tracing explanation been disproved? *

  1. The tracing explanation alone accounts for the blurred carpet.
  2. Mechanical devices have been proposed. It has yet to be demonstrated that they could generate the accuracy and subtlety of detail found in the painting.
  3. Perspective lines should meet at a single point. Should they for an object as complex as the chandelier? Stork says yes and Falco says no. Falco shows for the chandelier and a model system that they do not. This seems convincing.
  4. No. Stork claims that a concave mirror could not account for the effects. This does not apply as Caravaggio likely used a convex lens.
  5. It is generally accepted that Vermeer used a camera obscura.

SUMMARY: Mechanical devices have been proposed but have not been demonstrated. Theoretical expectations for the perspective properties of complex objects seem unclear. Falco avoids this convincingly by making comparisons with model systems. Any alternative has to demonstrate the capability of generating the optical effects.

D. What other explanations can account for the "optical" features? *

  1. No explanation has been offered or demonstrated to simulate a blurred carpet.
  2. Nobody has yet demonstrated that an exact copy can be made freehand.
  3. None so far. It remains to be shown that the chandelier could be drawn freehand.
  4. Such distorted perspective could not have been drawn freehand.
  5. Use of the camera obscura is accepted. An uncertain issue is the extent to which optical highlights are due to Vermeer or traced from the camera obscura.

SUMMARY: No blanket explanations have been advanced to account for all the features in the different paintings. The freehand sketching of these objects by eye can be no blanket explanation. It might account for the chandelier. It can never account for the carpet being out of focus. Instead of advancing alternative explanations, opponents have tried to show that the "optical" explanation is invalid or inconsistent.

E. Have "optical" features been reproduced by tracing a projected image? *

  1. Nobody has painted patterned carpets using projected images.
  2. Nobody has demonstrated exact reproductions using projected images.
  3. Nobody has painted a complex chandelier using projected image.
  4. Nobody has simulated this distortion of perspective using projected images.
  5. Nobody has used a camera obscura to create a Vermeer-like painting.

SUMMARY: People have shown that these optical effects could have been generated as a consequence of tracing an projected image but nobody has generated a painting, showing optical effects, by tracing a projected image.


The summary findings tell us that the same conclusions hold consistently for each of the five test paintings. These paintings were chosen because they show special optical effects not seen in normal paintings. These effects include regions of the painting out of focus, the distortion of perspective, the rendering of complexity in perspective difficult, if not impossible, freehand, the making of accurate copies, and the achievement of a photographic look and optical highlights.

All of these are possible consequences when artists trace projected images. In no case is there a clear argument that eliminates that as an explanation. Nor are there alternative explanations that can account convincingly for these effects.

These effects are the clues that reveal that certain artists in certain cases made paintings by tracing projected images. With that insight, we can understand why certain major paintings by certain major artists look as they do. We can understand how certain seemingly impossible technical challenges become possible. It is a technical matter that has no bearing on the quality of the work of art and on the quality of the artist. It is, as David Hockney remarks, the artist, and not the optics, that makes the marks.

Tracing projected images is a plausible and convincing explanation for these effects. What are needed to complete this story are actual demonstrations. We need to see artists painting chandeliers from projected images, artists making exact copies from projected images, artists using the camera obscura to create paintings as Vermeer must have done. We still do not know precisely how he did it even though we are convinced that he did.

Why is this not happening? Only artists have the technical ability to run these tests. Such tests take time and the issue is not a priority for artists. Those for whom it is a priority, lack the skills to do it.

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