Fig. 1.

Changes in the way researchers render biological images. a The camera lucida is an optical device that projects a semitransparent image of a microscopic field of view onto the same plane as a sheet of drawing paper. Using this device, a scientist can trace exactly what they see in the microscope onto paper (illustration from 1857 catalogue of Messrs Ross). b Once photography was invented, it was obvious that microscopes should be equipped with a more automated way of generating a lasting rendering of what is in the field of view of a microscope objective. Shown here is the Zeiss Ultraphot I, the company’s first commercial photomicroscope (courtesy of Carl Zeiss Microscopy GmbH). c The first scanning confocal microscope as described by Marvin Minsky in his patent of 1957 [28]. This device used electromagnets (see labels 46 and 54) to move a sample (11a) in a raster pattern. The sample was illuminated with a focused spot of light and the return reflected light passed through a pinhole and was detected by a photomultiplier tube (PMT). The analog output of the PMT was displayed on an oscilloscope. d The first digital image shows Walden Kirsch in 1957 (lower right), son of the team leader that built the first image scanner [29]. The image is the sum of two binary scans set at different thresholds to produce approximate gray levels. This panel also shows a digital camera image that Walden himself took 40 years later of his own daughter at much higher resolution than the 176 × 176 pixels of the image of him and 24 bit depth rather than the binary (1 bit) depth. © 1998 IEEE. Reprinted, with permission, from Kirsch RA. SEAC and the start of image processing at the National Bureau of Standards. IEEE Ann History Comput. 1998;20(2);7–13; all rights reserved