A-61580 November 2007
2-19
Image header
information
An image header is associated with every image captured by the
scanner. Following is a list of information available in the image header
.
Image length
size of the image.
Image identifier
indicates whether the image is front black and
white, back black and white, front color or back color.
Resolution
the scanner records the selected scanner image
resolution in dots per inch.
X-axis upper left
pixel horizontal offset to upper left corner of the
image. For more information, see the next section entitled “Zone
processing”.
Y axis upper left
pixel vertical offset to upper left corner of the
image. For more information, see the next section entitled “Zone
processing”.
Width
the scanner records the number of pixels-per-line in the
image. Width is also referred to as
line length
.
Length
the scanner records the lines-per-page in the image. Length
is also referred to as
page length.
Bits-per-pixel
bits-per-pixel can equal 1 for black and white
imaging. 8 for grayscale or 24 for color imaging. Bits-per-pixel is also
referred to as
pixel depth.
Compression type
the scanner records the compression type used.
Values for black and white images are: No Compression, Group III,
Group III 2D or Group IV. The values for grayscale or color images are
No Compression or JPEG.
Polarity
the scanner records image polarity. White pixels can be
indicated as 0 or 1.
Deskew
the image header reflects whether or not the scanner was
asked to perform deskew. If deskew is enabled, the image header also
indicates whether or not the document was deskewed. The maximum
angle the scanner will deskew is 44.9 degrees.
Skew angle
image header records the skew angle which was
determined for the scanned image. A severe skew angle may result in
no deskew being performed.
If the scanner is unable to determine a skew angle, the image will not
be deskewed. The skew angle field of the image header will be set to 0.
