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carbon monoxide particles on the surface of the tape) and 
second, the recording speed. A defective layout of those 
particles on the tape can result in ondulations of the 
images, acoustic distortions, and volume variations. On 
the contrary, the recording speed accounts for the amount 
of information stored on the videotape. The more elevated 
the speed, the higher the amount of information. Video 
images can be reproduced fifty times per second or sixty 
times per second, depending on the country television 
standards (PAL, NTCS, SECAM)*. The standard in 
Western Europe is PAL. That means that video is consitued 
by 25 frames per second. Every frame of the videorecording 
is made up of a number of lines. There are two fields which 
contain these lines. The first field contains the odd lines of 
the images and the second field contains the even lines. 
Although the quality of videorecording is higher using a 
professional or S-VHS camera, the experiment has been 
conducted using a VHS videocamera, because VHS is the 
least expansive system, and the most popular among non 
professional filmakers. 
3. A CASE STUDY 
The useful application of images derived from video 
recordings for the purpose of image rectification was 
investigated through a case study. The experiment was 
carried out on the east facade of the “Conservatorio 
dell’Annunziata,” a historic building in Palermo, Italy, which 
dates back to the seventeenth century. At present, all that 
remains of the original structure are the exterior walls 
which are propped up by metal scaffolding. In the sur 
veyed facade, there are no protruding element and it has 
a planar shape with three rows of windows spaced at reg 
ular intervals. 
3.1 Videocamera Surveying 
As described above, the video of the facade of the 
“Conservatorio dell’Annunziata” was taken using an ana 
logical videocamera, namely a Philips Explorer VKR 6840 
Hq VHS/c, with the following specifications: lens f/1,4, 
focus 9-54 mm, electric zoom 6:1, two speeds and auto 
matic recorder of the stop - automatic focus, exposure and 
white balance - electronic shutter at 1/250, 1/500, 1/1000 
sec.; PAL color television transmission standard; FM 
brightness recording; color recording VHS; sliding film 
speed at 23,39 mm/sec or at 11,70 mm/sec.; recording for 
mat 1/2” CCD, images at 400 lines. 
H PAL (Phase Alternate Line) is a color television stan 
dard in Western Europe, anglophone Africa and Middle 
East. The scan rate is 625 lines at 50 Hz. Motion video is 
played back at 25 frame per second. NTSC (National 
Television Standards Committee) is a color television tran 
smission standard in the United States, Japan and coun 
tries in the Pacific. The scan rate is 525 lines at 60 Hz. 
Motion video is normally played at 30 frames per second. 
SECAM (Système Electronique pour Couleur avec 
Mémoire) is a television transmission standard in France, 
Russia, Eastern Europe and francophone Africa. The scan 
rate is 625 lines, and lines alternate between green plus 
blue and green plus red. It does not need any colour or tint 
controls. 
The film was taken by setting automatic exposure, focus, 
etc. The facade was framed by a general shot and by two 
strips, an upper one and a lower one, with an overlapping 
area of almost 50%. Visual details of the facade were also 
taken to complete the documentation. At the the same time 
a recording of sounds was taken. While shots constitute a 
dynamic exploration of the structure within a given context, 
a sound recording is useful for studying the peculiar 
acoustic characteristics of the place. 
3.2 Acquisition of the Digital Images 
Acquisition of digital images was conducted by using three 
different software: Avid Media Suite Pro 3.0; Avid 
MCXpress] and Avid Videoshop 3.0. These are software 
dedicated to digital video editing which display functions of 
digital acquisition of film, radiometric calibration of film, 
and the capturing of single images. 
Media Suite Pro 3.0 and MCXpress are professional-qual 
ity software that require a personal computer and some 
dedicated pieces of hardware equipment. On the contrary, 
Videoshop is a low-cost software which can be effectively 
used with a personal computer without purchasing addi 
tional hardware. 
Acquisition by Media Suite Pro. Media Suite Pro 3.0 is 
a professional, desktop digital editing system which 
requires a system configuration composed of two moni 
tors, a videorecording, a personal computer, and addition 
al pieces of hardware. In this experiment, the following 
hardware was used: Sony Trinitron KX-14 CP1 tv monitor; 
Panasonic NV-HS1000 videorecorder; computer Quadra 
900, Ram 64 Mb, HDD 2 GB, Vram 4 Mb, with four boards: 
Avid JPEG video compression board, truevision digitazing 
and display board, audiomedia audio board, SCSI 
Accelerator board, and a Sony monitor. 
Before the acquisition, it is possible to choose the format 
of the signal and the image resolution. The format can be 
Pal o NTSC The resolution can be of three different for 
mats: MSP-1 provides the lowest image quality and pro 
duces video with one field of information using 24-bit color; 
the video captured using this resolution is about 14 min 
utes per Gigabyte. MSP-2 produces video with two fields 
of information using 24-bit color, and 9 minutes per 
Gigabyte, with a higher quality than MSP-1. MSP-3 pro 
vides the highest image quality and produces video with two 
Figure 1 - Image Acquired by Media Suite Pro