Cinematography-Theory-And-Practice

Output0255255255InputInput3D LUTsticeor cube where each axis is an entry point for one of the threecolor components (Figure 13.8). Output values are calculated byinterpolating between the nearest points in the lattice. As with other bit depths. The mostcommon practice is to use RGB 10 bit/component log images as thecalculating the output values from an input by looking for the near-(255, 255, 0)(0, 255, 0)(255, 0, 0)(255, 0, 255)(255, 255, 255)(White)(0, 255, 255)(0, 0, 255)Figure 13.7. (top) A 1D LUT hasseparate tables for each color channel.(Illustration courtesy of LightIllusion.)Figure 13.8. (bottom) A 3D LUT is acube or lattice. The values of 0 to 255in both of these are the digital colorvalues. (Illustration courtesy of LightIllusion.)CAMERA FILTER TYPESThere are a few basic types of filters:Diffusion and Effects FiltersThere are many types of diffusion filters, but they all have onecommon purpose: they slightly alter the image to make it softer ormore diffuse or to reduce the contrast. They do it in a number ofways and with a variety of effects (Figures 13.9 through 13.12).Nearly all diffusion filters come in grades: 1, 2, 3, 4, 5 or 1/8th, 1/4,1/2, 1, 2, and so on. Most rental house will send them out either as aset or as individual rentals. All types of filters usually come in a protectivepouch and often have some soft lens tissue wrapped aroundthem inside the pouch to make it easier to handle the glass withoutadding fingerprints that need to be removed later.Diffusion filters are a very personal and subjective subject. Besidesglass or resin filters, which are placed in front of the lens (or in somecases behind the lens or even in a slot the middle of it), other meth-they generally come in sets ranging from 1 to 5 or 1/8, 1/4, 1/2, 1,2, and so on. An older type of filter that dates back to the early daysof the studio system but that is still popular today are the Mitchelldiffusions, which come in grades A, B, and C.Other types of loose open material can be used, as can as greaseor petroleum jelly on a piece of glass. Ordinary cellophane or plasticwrap have also been employed in emergencies. Star filters, whichcreate a pattern of streaks around a highlight, are basically clear glasswith diagonal scratches.There are some things to beware of when using diffusion filters.They will give different degrees of diffusion depending on the focallength of the lens beings used: a longer focal length lens will appearto be more heavily diffused. Some DPs drop down to a lower degreeof diffusion when changing to a longer lens. Tiffen, a major manufacturerof camera filters, has created digital filters in its Dfx software,which can used in postproduction to reproduce the effect of theirglass filters. Be careful about judging the effect of diffusion filters ona small on-set monitor, which can be deceiving. To judge any kindof alterations to the look a large monitor is usually required.cinematography256