CHAPTEE XYL 

 COLOR-CORRECT PHOTOGRAPHY. 



" ORTHO-CHROMATIC," or as we prefer to call it, " Color- 

 Correct " Photography, is one of the latest important improve- 

 ments in our science. It may be well to explain the rationale 

 of this modification of common processes, and the reader is 

 begged to study carefully our introductory remarks to this 

 chapter. 



It has been probably remarked by all observant people that 

 while the colors yellow, bright red, and certain greens appear 

 to the eye the most luminous colors, they are in photography 

 rendered as dark, or at least as below the average grade of 

 light, in the landscape, portrait, or copy of a colored drawing. 

 On the other hand the indigo and violet colors of an object 

 seen in the usual way appear to the eye dark or at least sub- 

 dued tints ; while these colors, when portrayed in the mono- 

 chrome of photography, are represented as high lights. This 

 has always been a serious objection to photographic ren- 

 dering of many objects, notably of painted pictures, and to a 

 considerable extent of landscape with foliage and sky effects. 

 It is evidently a very serious objection to photo-micrography 

 if we render an object, stained (say) with the dark violet of 

 logwood and the bright red of eosine or magenta, the very 

 opposite of what it really is visually ; viz. : bright in the print 

 where the object is dark violet, and dark in the print where in 

 the section there is a fine glittering red. Further, if we have 

 an object entirely red or entirely yellow but in gradations of 

 red or yellow, it is most annoying to get a print of a homo- 

 geneous blackness, simply because our plate is practically in- 

 sensitive to even the palest of the red or yellow. The diffi- 

 culty also is great with an ordinary plate where we have either a 



