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The Ratio Method

The ratio method is based onthe mathematical verity that the original width is to the reproductionwidth as the original depth is to the reproduction depth. If the reproductiondepth is the unknown (as is most often the case), the formula is:
(RW ÷ OW) x OD = RD Example A: ReducingThe PhotoThe original is a photograph 39 picas (61/2inches) wide by 48 picas (8 inches) deep. You want the reproduction widthto be 25.5 picas (that's 251/2 picas or 25p6). Youneed to calculate what the reproduction depth will be. The following assumesyou will proceed with a calculator.
25.5 ÷39 = 0.6538461
Thus, you would indicate a depth of 31.4 picas(or apporoximately 51/4 inches) on the layout.
The original is a photograph 27 picas wide by 16picas deep. You want the reproduction width to be 39 picas.
Thus, you would indicate a depth of 23.1 picas. The potential danger is this method of calculation is forgetting to convertpica measurements to decimals. Remember, for instance, that the expression25p6 means 25 picas and 6 points. The 6 points, of course, are equal toone-half of a pica. So 25p6 should be entered in a calculator as 25.5 picas.Remember that 3 points equal .25 picas, 6 points equal .5 pica, 9 pointsequal .75 pica, etc. | |||||

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TheRule of the Diagonal | TheProportion Wheel | |||||

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