We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.
Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.
atic image on the screen. This process, which Heraut has taken up anew, has the following disadvantages :
i . Negative and positive films of three times the length of black and white films must be used ;
2. The ribbon, being turned at three times the normal speed, is soon worn out ;
3 . The most serious drawback consists in the impossibility of obtaining a perfect superposition of the images whenever a moving object moves perpendicularly in relation to the axis of the objective. Indeed, notwithstanding the great speed with which the images succeed one another, a moving object cannot when photographed be precisely in the same position in each of the three images. Thus the superposition is not absolutely perfect and coloured rims appear on the screen.
2. The Frees Green TwoColour Process.
Notwithstanding any imperfections in this process, it is being exploited industrially on account of its relative simplicity. It consists in taking two simultaneous images, each with the aid of a complementary screen — one green and one red. To obtain the positive, a film prepared with emulsion on both sides — one serving for the printing of the red and the other of the green image — is used, care being taken to insensitize the gelatine layer which is not being used at the moment, between each operation, and to see that the two images are placed accurately one over the other.
These two positive images are coloured respectively green and red, by successively isolating the two surfaces of the film.
The most serious drawback to this system is the use of only two colours ; the hues are consequently not accurate ; blue cannot be reproduced and the remaining colours, in which blue is lacking, are not faithful to nature.
The impression on the eye is generally somewhat disagreeable, when the colours which predominate in the scene are not green and red. In printing, moreover, the precise coincidence of
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