Cinematography-Theory-And-Practice

Figure 9.33. (top) In this frame theknee (brightest part of the grayscaleat far right on the curve) is clipped:the curve flatlines at 108%.Figure 9.34. (bottom) The samegrayscale, and same exposure, butknee control is dialed down. Thiskeeps the brightest parts of the shotfrom clipping with changing the restof the picture.ClippingOther CodecsTIFF is Tagged Image File Format. It can be a container for either lossyor lossless image data. Some post processes deal with the video filesas a series of TIFF images that can be very large but also very highquality. JPEG (Joint Photography Experts Group) is another file typeusually associated with still cameras and computer graphics but alsoused in video. JPEG is a lossy format but can reputedly achieve compressionratios of as high as 10:1 without noticeable loss of visualquality but if overused can result in very poor picture quality. MotionJPEG renders the video as a series of lossy JPEG images.Each frame is compressed separately (intra-frame) and is thus notas efficient as inter-frame codecs, however, it imposes less of a loadon the processing power of the computer. With inter-frame codecs,the computer needs to constantly refer to other frames as it displayseach individual frames. JPEG2000 is a more complex and computationallyintense codec that is wavelet based. OpenEXR is a highdynamic range (HDR) file format. High dynamic range means that itcan handle images with greater latitude/brightness ration/dynamicrange (see the chapter on Exposure for a discussion of latitude anddynamic range). It supports 16 bits per channel and has an extraordinarydynamic range of 30 stops. It can be used as either a lossy orlossless codec.cinematography176