Screentone is a technique for applying textures and shades to drawings, used as an alternative to hatching. In the conventional process, patterns are transferred to paper from preprinted sheets, but the technique is also simulated in computer graphics.
A Screentone is, in printing and in technical drawing, a surface composed of either evenly spaced points or predefined lines, thickness and spacings, which have the effect of visually giving different gray values. The majority of printing techniques do not make it possible to directly obtain shades and gradations of the same color: for that purpose, it is necessary to go through the screening stage, which consists in transforming an image into half-tones (a photograph). ) in a succession of points more or less thick and tight.
In technical drawing, prior to the generalization of computer-aided design (CAD) and computer science, conventional hatching was used to represent various elements (materials, etc.). This work was done manually. In 1937, the United States Zip-a-Tone brand, which provides a pre-printed frame on a paper support, then film, just cut and stick to the desired locations. Then it is Chart-Pak in 1949. The process spreads internationally from the 1970s with the Letratone of the company Letraset (1966) at the same time as the transfer characters proposed by the same manufacturers develop. The frames are printed on transparent adhesive films and represent a large number of dots, lines, flat or gradient. Superimposition of two frames can give moire effects. After the regular “mechanical” frames, we have created frames of irregular textures, grains, entangled lines, patterns, etc. The use of these frames has therefore spread rapidly from the technical field to graphics and illustration.
A traditional screentone sheet consists of a flexible transparent backing, the printed texture, and a wax adhesive layer. The sheet is applied to the paper, adhesive down, and rubbed with a stylus on the backing side. The backing is then peeled off, leaving the ink adhered to the paper where pressure was applied.
A screentone saves an artist’s time by allowing quick application of textures to line art where a hand-shaded area would not be reproduced in a timely or acceptable manner. Much like halftone, the size and spacing of black dots, lines, or hatches determine how light or dark an area will appear. Visual artists need to take into account how much an image will be reduced when prepared for publication when choosing the pitch of a screentone. Screentones can also be layered to produce interference patterns such as moire effects, or to simulate multiple sources of shadow in an image.
Different styles of screentone exist, variously intended to depict clothing, clouds, emotions, backgrounds, gradients and even objects such as trees. While the sheets are most commonly produced with black ink, there are also varieties in solid and patterned colors. Screentones can also be modified by lightly scratching the backing with an X-Acto blade to produce starbursts and other special effects.
In architecture mechanical frames were used to represent materials: brick, stone, pavements, floors, tiles, slates. In the same way, all the constituent elements of a plane are represented by “transfer” figures (furniture, sanitary, technical elements, vegetation, vehicles, characters) in plan and in elevation, at different scales.
On the same principle, adhesive films appeared that were no longer “frames” in the strict sense, but more or less transparent color surfaces that could be used for coloring. The weft term, although unimportant, continued to be used for these materials.
Diazography is a method of map reproduction widely used in architectural or technical design in the course of the twentieth century.
Diazography uses plastic self-adhesive films, also called frames, of varying color and opacity to achieve large shading areas and shadows. The films are glued on the tracing paper between and in the lines of the drawing, made in a conventional manner using line pulls or technical pens.
In the diazo plane printer, a device using diazography as a method of reproduction, the frames took on the paper different shades and textures of gray (more exactly shades of blue).
With the computer-aided design and the first feather plotters, the use of the frames used in diazo is not totally obsolete: the shading surfaces can be obtained by repeated juxtaposition of points, but this causes a significant mechanical stress to the machine.
With the advent of inkjet tracers, the use of mechanical frames, “transfer”, or diazo falls into disuse.
Frames have been widely used in all areas of graphic design: illustration, press drawing, advertising, comics and manga. When technical constraints do not allow the use of color, the frames quickly give different gray values and effects of material or texture.
Screentones are widely used by illustrators and artists, especially for cartoons and advertising. Use of the original medium has been declining since the advent of graphics software and desktop publishing, but it is still used, for example in manga.
While computer graphics software provides a variety of alternatives to screentone, its appearance is still frequently simulated, to achieve consistency with earlier work or avoid the appearance of computer-generated images. It is sometimes accomplished by scanning actual screentone sheets, but original vector or bitmap screen patterns are also used.
Source From Wikipedia