read_sequence ( : Image : HeaderSize, SourceWidth, SourceHeight, StartRow, StartColumn, DestWidth, DestHeight, PixelType, BitOrder, ByteOrder, Pad, Index, FileName : )
Read images.
The operator read_sequence reads unformatted image data,
from a file and returns a "suitable" image.
The image data must be filed consecutively pixel by pixel and
line by line.
Any file headers (with the length HeaderSize bytes)
are skipped.
The parameters SourceWidth and SourceHeight
indicate the size of the filed image.
DestWidth and DestHeight indicate the size the
image which is read should have. In the simplest case
these parameters are the same. However, areas can also be read.
The upper left corner of the required image area can be determined
via StartRow and StartColumn.
The pixel types 'bit', 'byte', 'short'
(16 bits, unsigned), 'signed_short' (16 bits, signed),
'long' (32 bits, signed) and 'swapped_long'
(32 bits, with swapped segments) are supported.
Furthermore the operator read_sequence enables the
extraction of components of a RBG image if a triple of three bytes
(in the sequence "red", "green", "blue")
was filed in the image file.
For the red component the pixel type 'r_byte' must be chosen, and
correspondingly for the green and blue components 'g_byte' or
'b_byte', respectively.
'MSBFirst' (most significant bit first) or the inversion thereof
('LSBFirst') can be chosen for the bit order (BitOrder).
The byte orders (ByteOrder) 'MSBFirst'
(most significant byte first) or
'LSBFirst', respectively, are processed analogously.
Finally an alignment (Pad) can be set at the end of
the line: 'byte', 'short' or 'long'.
If a whole image sequence is stored in the file a single image
(beginning at Index 1) can be chosen via the parameter
Index.
Image files are searched in the current directory (determined by
the operating system environment) and in the image directory
of HORUS
The image directory of HORUS is preset a '/bilder' and
'/usr/local/horus/images' in a UNIX environment
and can be set via the operator set_system.
More than one image directory can be indicated by separating the
individual directories by blanks.
Furthermore the search path can be set via the environment variable
HORUSIMAGES (same structure as in 'image_dir').
Example:
setenv HORUSIMAGES "/usr/images /usr/local/horus/images"
HORUS also searches the image in the sub-directory "images" (images for
program examples). The environment variable HORUSROOT is used for the
HORUS directory.
Parameters
Image (output_object)
|
image -> object
|
Image read. |
HeaderSize (input_control)
|
integer -> integer
|
Number of bytes for file header. |
Default value: 0 |
Range of values: 0 <= HeaderSize |
SourceWidth (input_control)
|
extent.x -> integer
|
Number of image columns of the filed image. |
Default value: 512 |
Range of values: 1 <= SourceWidth |
SourceHeight (input_control)
|
extent.y -> integer
|
Number of image lines of the filed image. |
Default value: 512 |
Range of values: 1 <= SourceHeight |
StartRow (input_control)
|
point.y -> integer
|
Starting point of image area (line). |
Default value: 0 |
Range of values: 0 <= StartRow |
Restriction: StartRow < SourceHeight |
StartColumn (input_control)
|
point.x -> integer
|
Starting point of image area (column). |
Default value: 0 |
Range of values: 0 <= StartColumn |
Restriction: StartColumn < SourceWidth |
DestWidth (input_control)
|
extent.x -> integer
|
Number of image columns of output image. |
Default value: 512 |
Range of values: 1 <= DestWidth |
Restriction: DestWidth <= SourceWidth |
DestHeight (input_control)
|
extent.y -> integer
|
Number of image lines of output image. |
Default value: 512 |
Range of values: 1 <= DestHeight |
Restriction: DestHeight <= SourceHeight |
PixelType (input_control)
|
string -> string
|
Type of pixel values. |
Default value: 'byte' |
List of values: 'bit', 'byte', 'r_byte', 'g_byte', 'b_byte', 'short', 'signed_short', 'long', 'swapped_long' |
BitOrder (input_control)
|
string -> string
|
Sequence of bits within one byte. |
Default value: 'MSBFirst' |
List of values: 'MSBFirst', 'LSBFirst' |
ByteOrder (input_control)
|
string -> string
|
Sequence of bytes within one
'short' unit. |
Default value: 'MSBFirst' |
List of values: 'MSBFirst', 'LSBFirst' |
Pad (input_control)
|
string -> string
|
Data units within one image line (alignment). |
Default value: 'byte' |
List of values: 'byte', 'short', 'long' |
Index (input_control)
|
integer -> integer
|
Number of images in the file. |
Default value: 1 |
Range of values: 1 <= Index |
FileName (input_control)
|
filename.named -> string
|
Name of input file. |
Result
If the parameter values are correct the operator read_sequence
returns the value TRUE.
If the file cannot be opened FAIL is returned.
Otherwise an exception is raised.
Possible Predecessors
read_info
Possible Successors
disp_image,
count_channels,
decompose3,
write_image,
rgb1_to_grey
Alternatives
read_image
See also
read_image,
read_picture
Copyright © 1996-1997 MVTec Software GmbH