. The half-tone process. A practical manual of photo-engraving in half-tone on zinc, copper, and brass. WHAT IS HALF-TONE ? 21. was covered up with something of a medium shade,neither black nor white—in fact, a half-tone—does itnot occur to the reader that the dots would be ofmedium size? That is practically what happens, but to assume thiswe must suppose that each dot starts with a nucleuswhich grows with greater and greater intensity of lightor longer we examine anegative under apowerful micro-scope we find thatis exactly whatdoes occur. is a portion ofa negative verygreatl
. The half-tone process. A practical manual of photo-engraving in half-tone on zinc, copper, and brass. WHAT IS HALF-TONE ? 21. was covered up with something of a medium shade,neither black nor white—in fact, a half-tone—does itnot occur to the reader that the dots would be ofmedium size? That is practically what happens, but to assume thiswe must suppose that each dot starts with a nucleuswhich grows with greater and greater intensity of lightor longer we examine anegative under apowerful micro-scope we find thatis exactly whatdoes occur. is a portion ofa negative verygreatly enlarged,and it shows clearlythat each dot is,so to speak, a littlemound of reduced Fig. 6. silver. It may be that there are other causes operating toassist in producing this effect —for instance, the naturaltendency of the silver particles to communicate theiraction to neighbouring particles, and to spread theimage according to the intensity of the light andchemical action; whilst there may be also causes actingin opposition to retard this action and produce sharplydefined dots with clear spaces. Diffraction is k
Size: 3043px × 821px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookidhalftoneproc, bookyear1904
