Problems Associated With Reading Matrix Code; Matrix Width; Matrix Position - evertz 5550 Operating Instructions Manual

Model 5550 Universal Film Data Decoder Manual

3.5.1. Problems associated with reading matrix code

Depending on the camera type, matrix code burner, camera operator and
film processing, there is a wide variation of matrix code. The size, position,
contrast, distortion of the matrix and various other artifacts are possible.
The Evertz UV heads and 5550 decoders are designed to handle a large
variety of these film-to-film differences. Here is a brief description of the
types of variations to expect, how we handle the variation and how to
identify when there may be a problem.
3.5.1.1.

Matrix Width

On 35mm film, the width of the matrix can vary from filling the whole
marginal area (between sprocket holes and edge of film) to approximately
one half the size. Decoding of a wide matrix is not a problem until a
significant amount of the first or last column ends up overlapping the
perforation holes or the outer edge of the film.
On 16mm film, the width could be as large as to extend from the KeyKode
to the active film area. Decoding of both the KeyKode and matrix code will
be affected if the codes overlap. Matrix code decoding errors and active
picture artifacts will exist if the matrix overlaps with the active picture.
If the matrix is very narrow (i.e. if the matrix is less than half the width of the
area that is available), decoding may be affected due to the limited
resolution of the optical pickup device. Poor reading performance, due to
narrow code, will also be compounded if the film entrance/exit angle to the
head is steep, reducing magnification, or there is excessive side to side film
wobble.
The MATRIX SIZE extended display shows the width of the matrix that
the5550 is detecting.
3.5.1.2.

Matrix Position

The left/right registration of the matrix on the film marginal area can also
vary depending on how the matrix code writer was installed in the camera.
The 5550 Universal Film Code Decoder, using digital signal processing
techniques, finds and tracks the size and position of the matrix so that no
setup or calibration is required when the code changes from job to job. In
fact, a lab roll created from different cameras will not pose a problem to the
decoder because the algorithm will adapt to the different sizes/positions
automatically.
The MATRIX POS'N extended display shows the horizontal position of the
matrix that the 5550 is detecting.
OPERATION Page 3-16