Sony BVP-E10 Series, Product Information Manual

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167 Chapter 10 Glossary - Terms and Definitions
BVP-E10 Series Product Information Manual
synchronize the cameras to an external composite
video input.
Horizontal image enhancement (H DTL)
Horizontal image enhancement is performed by
boosting the frequency characteristic of the video
signals. In the case of analogue cameras, this is
carried out by using the Low Pass Filters and Delay
Lines, for while in digital cameras. it is achieved by
using digital filters.
H/V Ratio
Adjusts the relative amounts of detail correction in
horizontal and vertical directions.
Image enhancement
A function which gives an increase in the perceived
sharpness or resolution of a picture. It is extremely
difficult to quantify the effects of image enhancement,
so it does not appear in brochure specifications of the
camera. However, it has an important influence on
subjective picture quality. Image enhancement is
sometimes referred to as Aperture Correction, Contour
Correction, Detail Correction, or more simply as Detail
(DTL) In cameras, image enhancement is usually
applied both horizontally (horizontal detail, or H DTL)
and vertically (vertical detail or V DTL) directions.
IT/FIT
In an IT type of CCD, adjacent to the light-sensitive
pixels there are columns of cells dedicated for vertical
transfer, known as Vertical Shift Registers. The
electronic signals are transferred from the pixels to the
vertical shift registers during vertical blanking. Finally,
the signals reach a row of cells for horizontal transfer,
the Read Out Register, from where the signals are
output as video signals. Although the registers are
covered by an opaque metal film to prevent any light
from reaching the cells, sometimes leakage still
happens under a strong light, which causes smear. To
avoid this phenomenon, in an FIT type CCD, there is
additional storage area added to the CCD which
enables the vertical transfer to be performed much
more quickly so to minimize the chance of light
leakage even under a strong light. However, this
additional storage increases the overall size of the
sensor, and hence the cost. Recently, there have been
great advances in IT CCD technology and the gap
between IT and FIT has been dramatically reduced.
Knee aperture
Knee compression applied to the picture will also
reduce detail in the highlights. Knee aperture is a
technique which allows independent adjustment of the
amount of detail in the highlights.
Knee correction
The dynamic range of a natural scene is very large, but
that of a video interface standard is limited. If we use a
camera to shoot a subject against a very bright
background, if we use the iris to adjust for the correct
exposure of the subject, the bright backgraound of the
picture will become almost completely white. However,
if we expose for the bright portion, the subject will
become very dark. Knee correction is a function that
solves this problem by compressing the level of the
bright area to meet that in the video standard so as to
make the dynamic range seem larger. When
represented graphically, the characteristic resembles
the shape of a knee.
Knee point and knee slope
Knee point is the starting point of the knee correction
process, and the knee slope is its compression rate.
Knee saturation
In a conventional knee circuit, knee correction is
performed independently in R/ G/B channels. When
shooting a coloured object, the amount of
overexposure, and therefore the amount of knee
compression, will be different in each of the three
colour channels. This will result in a change in both the
colour phase and saturation of the coloured highlight.
Subjectively, skin tones will "wash out" and appear
yellowish. Knee saturation is a technique used to
balance the colouring to avoid this phenomenon.
Level dependency
Just like Crispening reduces noise, level dependency
is a circuit that decreases the detail value in dark
areas.
Limiter
CCD sensors have a very large dynamic range, and
can produce outputs up to 6 times normal signal white
level. On strong highlights, this can cause excessive
detail edges on the picture, giving an unnatural
"cardboard cut-out" appearance to the picture A limiter
is a circuit used to constrain the peak value of the
detail correction signal.
Linear matrix
The linear matrix is used in order to correct the colour
response of the camera to established standards,
such as SMPTE or EBU. The matrix compensates for
differences between the actual colour response of the
optical prism and the theoretical ideal. Typically six
matrix values are used to mix between the RGB
signals. User adjustment of the matrix characteristics
can have a strong influence on the subjective
colouring of the picture, but there is severe interaction
between the 6 parameters, which makes the
adjustment very difficult. But see Multi Matrix.
Mix DTL/NAM DTL
The recent trend has been for cameras to create
Vertical Detail from all three R/G/B channels. The
BVPE10 series cameras include two alternative
methods for combining these three signals. Mix DTL
provides a simple sum of the three components, while
NAM DTL uses a Non Additive Mix, which uses
whichever signal has the largest amplitude. NAM DTL
can be very effective when shooting material in
coloured lighting, for example at a music or theatre
event. However, it can introduce unwanted side-
effects, such as increasing the noise in the picture, so
the choice of techniques can be selected by the user.
NAM DTL is not applied to horizontal detail, since it
would increase aliasing.
Multi matrix
Conventional matrix adjustment can be used to
change the colour response of the camera, but with
severe interaction between different colours. Multi
matrix on the other hand offers an easy way of
manipulating colours to achieve a particular colour
effect. For instance, it is possible to change the colour
phase and saturation of red colour only. The colour
spectrum is divided into 16 separate ranges, each
independently adjustable. Conventional matrix
requires six matrix coefficients. However, to further
simplify operation, Sony's cameras use dedicated
software to reduce the adjustments required to just
two, colour phase and saturation.
On-chip-lens
In order to achieve high resolution, CCDs generally
use large numbers of pixels. However, increasing the
number of pixels means decreasing the individual