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.
seen that to render hue contrast in spite of this condition, a deliberate distortion has to be made. This is accomplished by the use of light filters, which for this reason are also frequently referred to as contrast filters.
Important in connection with this problem of deliberately distorted reproduction is the correct conception of the rather simple principles underlying the proper direction and the necessary degree of any contemplated distortion. To render a color lighter on the photographic brightness scale of the final reproduction, a filter must be used which selectively transmits the same color. To render a color darker a filter must be used which selectively absorbs this color.
"Warm" and "Cool" Colors
As far as the direction of the distortion is concerned there exist certain physical and psychological laws which make it appear best to render colors of longer wave length lighter than those of shorter wave length. The former include red, orange, yellow and yellow-green, and may be referred to as "warm colors." The latter include blue-green, blue and violet, and are called "cool colors." In case of non-spectral hues, the purples, which reflect red and violet, the ones in which red predominates, are classed with "warm colors," while those in which blue predominates are classed with "cool colors.” *
Special Viewing Filter
In addition to the monochromatic viewing filters mentioned above, another type of viewing filter is of interest and is also frequently used in practice. This filter is of a purple tint, thus enhancing red and blue colors, and depressing green-yellow radiation. The spectral transmission curve of such a filter is closest in shape to the spectral sensitivity curve of present Panchromatic supersensitive emulsions, both showing their maximum peaks in red and blue.
Viewing an object through this type of filter will enable one to visually anticipate the effect of the spectral reflection characteristics of the object upon the negative material before exposure. Thus we are able to construct visually for any object what was previously referred to and explained as the photicity curve.
Both types of viewing filters discussed are helpful in many ways for each problem, that of "Orthochromatic reproduction" and deliberately distorted reproduction.
Special Effect Photography
An interesting field in which the application of photographic distortion plays an important part is in the photographing of so-called "effect shots." This includes the many different methods of composite trick photography wherein the combination of foreground action and background is achieved by utilizing the possibilities of color enhancing and depressing filters.
Also, in this category belong photographing through haze and photographically producing night effects made in the daytime. While both of these tasks
* ( L. A. Jones, S.M.P.E. Journal. Vol. XI, number 30, page 164 and following.)
(Continued on Cage Sixteen)
Page Fourteen