ITU-R BR 1440-2000 16 9 Video Images Transferred to 35 mm Film for Optical Projection《传送到用于光学投影的35毫米胶片上的16 9 视频图象》.pdf

1、 Rec. ITU-R BR.1440 1 RECOMMENDATION ITU-R BR.1440*,*16:9 VIDEO IMAGES TRANSFERRED TO 35 mm FILM FOR OPTICAL PROJECTION (Question ITU-R 240/11) (2000) Rec. ITU-R BR.1440 The ITU Radiocommunication Assembly, considering a) that programmes produced on 16:9 video are transferred to 35 mm film for optic

2、al projection; b) that the 16:9 image on 35 mm film should match the television presentation; c) that current video to film transfer processes expose a camera film image and current printing and projection processes will crop the exposed image on film by about 4.6% overall; d) that at the moment, th

3、ere are no international standards for 16:9 film projection, recommends 1 that 16:9 video images to be transferred to film for conventional printing should be aligned to expose the image width dimensions according to the International Standard, ISO 2906, for camera exposed area (Cinematography Image

4、 area produced by camera aperture on 35 mm motion-picture film Position and dimensions). The height of the exposed image should correspond to the aspect ratio of 16:9 (see Table 1); 2 that the film should, if possible, be projected with a projector aperture of 16:9 aspect ratio (see Table 1); 3 that

5、, where possible, when composing 16:9 images on video that may be transferred to film, it should take into account the loss of image area that will occur during the printing and projection processes (see Annex 1); 4 that, when transferring video images that were not originally intended for projectio

6、n to 35 mm film, the possible loss of image area if the film is projected using an existing cinema projector aperture should be taken into account (see Table 2). TABLE 1 Standard and proposed dimensions of 16:9 camera aperture on 35 mm film _ *This Recommendation is intended to replace Recommendatio

7、n ITU-R BR.713-1, which is hereby deleted. *This Recommendation should be brought to the attention of the International Standardization Organization (ISO). Aperture Image width (mm) Image height (mm) Reference Exposure 21.95 12.35 ISO 2906(1)Projection 20.95 11.78(2)ISO 2907(3)(1)ISO 2906 Cinematogr

8、aphy Image area produced by camera aperture on 35 mm motion-picture film Position and dimensions. (2)ISO TC 36 is currently studying the 16:9 aspect ratio for an international projection standard. (3)ISO 2907 Cinematography Maximum projectable image area on 35 mm motion-picture film Position and dim

9、ensions.2 Rec. ITU-R BR.1440 ANNEX 1 Transfer of 16:9 television programmes to 35 mm film for optical projection: image dimensions 1 Background Video images may be transferred to film for optical projection. This happens in situations where it is convenient to be able to present television programme

10、s on a cinema screen. The more important situation is where the film is the end product in a mixed video and film production process. In particular, this transfer is useful when HDTV is used as an alternative method for feature film production. Different technologies are used to transfer video to fi

11、lm but common to all is the use of traditional printing of a film for projection. The TV aspect ratio of 16:9 is not yet an established standard for optical projection. It is therefore important to be aware of the consequences of merging video and film technologies for optical presentation. 2 Genera

12、l Most equipment for transferring images on video to film is based on transferring the video image from an image surface, or as a beam of light, optically onto a camera film in a camera much like an ordinary film camera. Then the camera film follows traditional film processes of printing and project

13、ion. 3 Properties of traditional film printing and projection The traditional image processes from camera to projection are specified in agreed international standards. These standards take into account the necessary flexibility and safety margins necessary for printing and projection. Therefore the

14、re is an overall image cropping from camera negative to projection of about 4.6%. A video image will therefore be reduced about 4.6% overall in this process (see Fig. 1). 1440-01Projected image height1.85:1 = 11.32 mm16:9 = 11.78 mm1.66:1 = 12.62 mmCamera aperture, 1.37:1Projected aperture width: 20

15、.95 mmCamera aperture width: 21.95 mm16:9 video exposed on negativeFIGURE 1Projected 35 mm image areas from 16:9 videoFIGURE 1440-01 = 9 CM Rec. ITU-R BR.1440 3 Further cropping may occur when 16:9 video images are optically projected. Each projector is equipped with exchangeable projection aperture

16、s. These relate to the different projection standards. The most frequently used wide-screen formats are 1.85:1 and 1.66:1 as well as anamorphic 2.39:1. There is no standard at present for 16:9 projection and existing apertures may be used instead. Using the 1.85:1 aperture for 16:9 images will crop

17、an additional 4% overall of the image height (see Figs. 1 and 3). 4 Transferring 16:9 video images to 35 mm film In principle there are two circumstances in which video images may be transferred to film: Images shot on video and framed for optical projection on 35 mm film. Programmes on video not or

18、iginally intended for optical projection. 4.1 Images shot on video and framed for optical projection on 35 mm film In a video to film production method it is necessary to shoot and frame to the presentation image area. This can be done by showing the projected area in the camera viewfinder. It is th

19、erefore recommended that camera viewfinders have markings similar to those in Fig. 2. 1440-021.85:1 optical projection (less 8.3% overall)FIGURE 2Video camera viewfinder for programmes intented for projection from 35 mm film16:9 acquisition16:9 optical projection (less 4.6% overall height)FIGURE 144

20、0-02 = 9 CM 4.2 Programmes on video not intended for optical projection When images on video are transferred to film without the attention necessary during shooting and post-production, there will be changes to picture content that is projected. It could be important for the programme makers to be a

21、ware that: The image width will be cropped 4.6% overall. The projected image height will depend on the projector aperture used. At the moment, the 16:9 aspect ratio is not used in cinemas. The current projection apertures that could be used and their effects on picture content are listed in Table 2

22、and shown in Fig. 3. 4 Rec. ITU-R BR.1440 TABLE 2 Projected images from 16:9 prints using different projector apertures 1440-03FIGURE 3Image area reduction when projecting 35 mm film transferred from 16:9 videoProjected image height1.85:1 = 11.32 mm16:9 = 11.78 mm1.66:1 = 12.62 mmProjected aperture

23、width: 20.95 mmCamera aperture width: 21.95 mm16:9 video on exposed negative (21.95 mm 12.35 mm)Projected 16:9video image(cropped 4.6%)FIGURE 1440-03 = 9 CM BIBLIOGRAPHY EBU 1998 Recommendation R94. Transfer of 16:9 television programmes to 35 mm film for conventional printing and optical projection

24、. Projected image Projection format Width Height Aspect ratio 16:9(1)Cropped by 4.6% overall Cropped by 4.6% overall 16:9(1)1.66:1 Cropped by 4.6% overall Full height of the printed video image, but overall 2% less than the projected aperture height 1.70:1 1.85:1 Cropped by 4.6% overall Cropped by 8.3% overall 1.85:1 (1)16:9 is not yet an internationally agreed standard for projection.