Enhanced Internet Imaging -
HTML Print and Scan
Version 10.27 of the
Black Ice Imaging Toolkits (TIFF, Image and Document
Imaging SDK/ActiveX) include the addition of the
PrintDIBPageEx method. The PrintDIBPageEx method
allows developers to print images directly from an
HTML page using programming languages such as Java
and VBScript.
Additionally, the latest
release of the Black Ice Imaging Toolkits include a
new sample application which demonstrates how to
acquire images from TWAIN compatible devices from an
HTML page. The new HTML scanning sample code has
been added to the toolkits and can also be accessed
directly from the Black Ice website at the following
address:
http://www.blackice.com/ImageInternet.htm
Developers can visit the
Black Ice website to download
the latest evaluation toolkits for themselves.
How to decode a scanned, faxed
or printed barcode symbol
Faxing Barcode
Symbols
There are many cases
where a developer will want to decode a barcode
symbol which was faxed using either the Fax
C++/ActiveX or some other means. Fax transmissions
are highly susceptible to acquiring “noise” during
the transmission which may block or break parts of
the transmitted barcode. When faxing barcode
symbols using the Fax C++/ActiveX, make sure that
ECM (Error Correction Mode) is enabled, and try to
send the faxes in Fine Fax resolution (204 x 196).
When faxing from a fax
machine, often times this will result in white lines
from the top of the image all the way to the bottom.
If one of these white lines happens to split a
single black bar from top to bottom, then that
barcode symbol may no longer be recognized/decoded.
In order to avoid this type of problem, the barcode
symbol should be printed vertically onto the page.
Printing Barcode
Symbols
Printing an image which
contains a barcode and maintaining a high symbol
recognition rate can be difficult, especially if the
image must be scaled before printing. Scaling an
image can produce distortion in the printed image
and can result in low recognition rates.
For best results, the
image that the Barcode symbol is created on should
have settings which are as close as possible to the
printer settings. For example, if printing to a
printer which uses a resolution of 600 DPI, the
initial image should be created with 600 DPI. Using
the same DPI in your image and printer will allow
the image containing the barcode symbol to be
printed without having to perform any scaling to the
image.
When printing from an
application which will scale images to fit the
printed page, if the image DPI and printer DPI
cannot be matched for some reason, try to set the
printer and Image DPI to fall within an integer
ratio, such as 2:1. For example, with a 200 DPI
image file, print to a printer using 600 DPI. This
way, every pixel in the original image will be
doubled, resulting in no additional distortion.
Printing a 200 DPI image to a 300 DPI printer will
result in every other pixel being doubled, which can
add sever distortion to the barcode symbol, even
though the barcode may appear correct to the human
eye.
Reliably Decoding
Barcode Symbols
In order to reliably
read and decode barcode, the portion of the image
containing the barcode symbol must contain a
sufficient number of pixels. Barcode decoding rates
are tied to the number of pixel contained in the
horizontal direction for each element in the
barcode. Barcode elements that are at least two
pixels wide produce reliable decoding rates, as long
as the angle of skew is kept relatively low.
Elements with a pixel width of four or more produce
can reliably be decoded no matter the skew angle.
Images which do not meet these base requirements
(containing single pixel wide elements or high
levels of skew and low pixel widths) may be
impossible to decode. Printer, scanner, and camera
resolution also play a part in a barcode symbols
decoding rate.
For best results when
decoding barcode symbols, try to enlarge the printed
symbol, increase the scanner, camera or printer DPI,
or move the camera closer to the object. Performing
as many of these steps as possible will increase the
number of pixels in each barcode element. The more
pixels per element, the higher the overall decoding
success rate.