open_framegrabber ( : : Name, FGWidth, FGHeight, Width, Height, StartRow, StartColumn, SquarePixels, Field, Bits, SpaceOrThresh, Gain, Generic, Device, Port : )
Open and configure a framegrabber.
The operator open_framegrabber
opens and configures the chosen framegrabber.
During this process in particular the link with the framegrabber is tested,
the framegrabber is (normally) locked for other processes and
if necessary memory is reserved as data buffer. The image is actually
grabbed via the operator grab_image. If the
framegrabber is not needed anymore, it should be closed via the
operator close_framegrabber, releasing it for
other processes. This automatically happens when another
framegrabber is opened. This means that only one framegrabber
can be open at a time.
For all parameters (except for name) -1 can be transferred
for integer, -1.0, for real and/or
'unchanged' for string values. In this case
the settings last chosen for this framegrabber
(i.e. the HORUS defaults on first call) remain unchanged.
The meaning of the particular parameters is as follows:
FGWidth,FGHeight Desired resolution of framegrabber.
Width,Height Size of the image area to be returned
by grab_image.
StartRow,StartColumn Upper left corner of the desired image area.
SquarePixels Statement whether square pixels
('yes') are desired or not ('no').
Field Number of desired half image
(0 / 1) and/or value 2 for a full image.
Bits Desired resolution of color and/or
grayvalues (typically 1, 8 or 24 bits).
SpaceOrThresh Desired color space (mostly 'rgb') for
colored images or threshold for
the binarisation of binary images
(1 bit). In the case of binary images
the pixels (as a region) are returned
with a brightness greater or the
same as the threshold set by grab_image.
Gain Amplification factor for the video
amplifier.
Generic Generic parameter (string
type) with framegrabber specific
meaning. This can be queried via
info_framegrabber.
Device Device name of the framegrabber card.
Port Port of the framegrabber the video signal
is linked to.
The operator info_framegrabber queries all possible parameters
of a concrete framegrabber which was opened before.
It is therefore advisable to first open the framegrabber via the HORUS defaults
(-1, -1.0 and 'unchanged').
Then the operator info_framegrabber returns all possible
parameter combinations by which the framegrabber (now in the modus
suitable for the conceptual formulation) can be opened again.
Attention
Due to the multitude of supported framegrabbers a large number of
parameters is necessary for the operator open_framegrabber.
However, not all parameters are needed for a specific framegrabber.
Parameters
Name (input_control)
|
string -> string
|
Framegrabber to be opened. |
Default value: 'UserFG' |
List of values: 'J300', 'MATROXMeteor', 'ProgRes', 'SlicVideo', 'SunVideo', 'VideoPix', 'VigraPix', 'ProgRes', 'UserFG' |
FGWidth (input_control)
|
extent.x -> integer
|
Desired horizontal resolution of framegrabber
(-1: leave value unchanged). |
Default value: -1 |
Suggested values: 998, 768, 720, 499, 384, 250, 192, -1 |
FGHeight (input_control)
|
extent.y -> integer
|
Desired vertical resolution of framegrabber
(-1: leave value unchanged). |
Default value: -1 |
Suggested values: 870, 580, 576, 575, 291, 288, 144, -1 |
Width (input_control)
|
rectangle.extent.x -> integer
|
Width of desired image area
(-1: leave value unchanged). |
Default value: -1 |
Suggested values: 998, 768, 720, 499, 384, 250, 192, -1 |
Height (input_control)
|
rectangle.extent.y -> integer
|
Height of desired image area
(-1: leave value unchanged). |
Default value: -1 |
Suggested values: 870, 580, 576, 575, 291, 288, 144, -1 |
StartRow (input_control)
|
rectangle.origin.y -> integer
|
Line number of upper left corner of desired
image area (-1: leave value unchanged). |
Default value: -1 |
Suggested values: 0, -1 |
StartColumn (input_control)
|
rectangle.origin.x -> integer
|
Column number of upper left corner of desired
image area (-1: leave value unchanged). |
Default value: -1 |
Suggested values: 0, -1 |
SquarePixels (input_control)
|
string -> string
|
Square pixels or not ('unchanged': leave value
unchanged). |
Default value: 'unchanged' |
List of values: 'yes', 'no', 'unchanged' |
Field (input_control)
|
integer -> integer
|
Desired half image (0/1) or 2 for full image
(-1: leave value unchanged). |
Default value: -1 |
List of values: 0, 1, 2, -1 |
Bits (input_control)
|
integer -> integer
|
Number of bits per pixel
(-1: leave value unchanged). |
Default value: -1 |
List of values: 1, 8, 16, 24, -1 |
SpaceOrThresh (input_control)
|
string -> string
|
The desired color space of colored images
(mostly 'rgb')
or the threshold for binarisation of binary images
('unchanged': leave value unchanged). |
Default value: 'unchanged' |
List of values: 'rgb', 'yuv', 'unchanged' |
Gain (input_control)
|
real -> real
|
Amplification factor for video amplifier
(-1.0: leave value unchanged). |
Default value: -1.0 |
Suggested values: 0.25, 0.5, 0.75, 1.0, -1.0 |
Generic (input_control)
|
string -> string
|
Generic parameter (framegrabber specific)
('unchanged': leave value unchanged). |
Default value: 'unchanged' |
Device (input_control)
|
string -> string
|
Device the framegrabber is linked to
('unchanged': leave value unchanged). |
Default value: 'unchanged' |
Port (input_control)
|
integer -> integer
|
Port of the framegrabber the video signal is
linked to (-1: leave value unchanged). |
Default value: -1 |
List of values: 1, 2, 3, -1 |
Example
query_framegrabber(:::FGs) >
< Selection of a suitable Framegrabbers FG from FGs >
open_framegrabber(::FG,-1,-1,-1,-1,-1,-1,'unchanged',-1,-1,'unchanged',
-1.0,'unchanged','unchanged',-1:) >
info_framegrabber(:::Width,Height,Bits,ColorSpaces,PixelRatios,Full,Explain) >
< Selection of a suitable Modus [W,H,B,C,YesOrNo,Field] with
YesOrNo = 'yes', if entry in PixelRatios = 1.0
Field = 0 or 1 (Full = 'false') or 2 (Full = 'true')
Generic sedate in accordance with Explain
and a suitable Image area [Wi,He,L,C] >
open_framegrabber(::FG,W,H,Wi,He,L,C,YesOrNo,Field,B,C,Gain,Generic,
'unchanged',-1:) >
grab_image(:Img::) >
close_framegrabber(:::).
Result
If the parameter values are correct and the desired framegrabber is
available at call time, open_framegrabber returns the value TRUE.
Otherwise an exception is raised.
Possible Predecessors
query_framegrabber
Possible Successors
grab_image,
info_framegrabber
See also
query_framegrabber,
info_framegrabber,
close_framegrabber,
grab_image
Copyright © 1996-1997 MVTec Software GmbH