ANAMORPHOSES; OR, DISTORTED FIGURES.
Having drawn a subject, such as a human face, on a piece of paper, enclose it in a square, as A, B, C, D (Fig. 130), and divide it into smaller squares by marking off equal parts of the sides and drawing straight lines across, as when you wish to make a reduced copy of a picture.
Fig. 132.
Describe a parallelogram, E, B, F, G, the short side, E, G, being divided into as many equal parts as A B, in our example 7. From the centre of the side, B F, draw straight lines to the points of division on the side E G. Assume the point I, on the side B F, as the height of the eye above the picture; draw from I to the point E the straight line, which cuts the lines diverging from H at the points 1, 2, 3, 4, 5, 6, 7. Through these intersecting points draw parallel straight lines to divide the triangle into as many trapeziums as there are small squares in the square A, B, C, D.
Now fill up all the cells of the triangle with corresponding parts of the drawing, taking the base of the triangle to be the head of the picture transferred, and the comical distortion will be made. To see it, however, like its original, bore a hole, K, in a board, L, placed upright in H, so that the height, L K, equals H I, which must not be great, in order that the distortion may be remarkable.
Several lines of letters forming a phrase or sentence, can be distorted in a similar manner, so as to be read only by holding the paper so inscribed at a certain position as regards the eye. Further anamorphoses may be made by painting on curved surfaces, cylindrical, conical, or spherical, which appear natural when seen from a certain point of view. Still another way is to look at the reflection on a cylindrical mirror of a drawing made only so to appear regular.
Another way to obtain the distorted picture is to prick out the outlines of the original drawing, and hold it at an angle to a sheet of paper, so that the light on the other side, streaming through the pinholes, shall form a figure, which you can trace with pencil, more or less out of the true position. To see this changed picture corrected, you must place your eye where the light was.
By varying such pictures, they can be adapted to being seen aright by reflections in cylindrical, conical, pyramidal, and prismatic mirrors.