AOH :: 2203.TXT|
Logitech document 2203: "Recognition Hints and Tips for Catchword Pro for Windows"
Document Number 2203
Recognition Hints and Tips for CatchWord Pro for Windows
1. Always scan in line-art or black and white mode.
There is a feature in CatchWord Pro for Windows which allows you to scan in
256 grayscale with the ScanMan 256 if your original has a colored
background. After the scanning process the program converts the image back
to line-art to give the best contrast possible. This feature should only
be used for originals which do not have white backgrounds. Otherwise,
scan in line-art mode.
2. Selecting The Right Resolution
Most magazines and text books should be scanned at 300 dpi. Use 400 dpi if
the text you are scanning is smaller than standard magazine size. For
normal sized text (8 to 15 points), 300 dpi is the best resolution. Use 200
dpi if you are scanning large blocks of headline-style type.
Text Size Scanner Resolution (DPI)
6 to 8 Points 400 DPI gives best results
9 to 15 Points 300 DPI gives best results
16 to 20 Points 200 DPI gives best results
3. Adjusting Contrast
Contrast control (the relative amounts of black and white) is critical in
obtaining a good scan. If the text to be scanned is too faint and the
scanned image shows excessive broken characters, then the recognition will
be poor due to the unrecognized characters. If the scan is too dark, the
letters will run together and cause poor recognition. In any initial
scanning of a new image, you will need to adjust the contrast. CatchWord
Pro for Windows tends to prefer a darker contrast, so start with the
contrast setting slightly darker than the middle notch on the scanner.
4. Scanning Speed
For the best image quality, experiment with the scanning speed to
determine the best rate for your computer. You should be scanning at an
acceptable rate so the speed indicator light on the scanner head does not
flash. When you scan too fast the characters may look compressed, which
causes character size inconsistencies. Try to scan a bit slower than the
normal rate recommended by the scanner software, perhaps at about 1/2 to
1 inch per second. This way the system can receive and process all of the
incoming scanned data in time.
Make sure your scanning does not get too far ahead of the real-time
display. On slower machines the disk access speed cannot keep up the with
the rate of incoming data passed from the scanner to the machine channel.
Before you hit RETURN to activate Recognition, view the entire image to
check whether all the data is captured to screen. When you have scanned
too fast for the system, you may notice the final image displayed will have
loss of data, i.e., certain chunks of paragraphs are missing. In this case,
you will have to rescan slower. Scanning too slowly will not affect the
quality of the scanned image.
5. Scanning Straight
When the actual scan is slanted, skewed, or jagged, the text will not
be recognized fully. Use a hard edge ruler or the edge of a book to help
As you become more and more familiar with the way CatchWord Pro works -
what it recognizes and what it doesn't - you will find your results
7. Full Page Scanning
You get best results scanning horizontally when attempting to scan a full
page. Be sure to select the landscape multiple strip scan mode icon. Begin
and end each strip at the same place on the page, and overlap four lines of
text. You may need to scan in three strips instead of two to get the full
Following are the most common reasons why an OCR program may misread text:
Unrecognizable fonts or characters. Omnifont technology recognizes
standard fonts by comparing text characters to features programmed into the
software. The software will not read characters which don't match
programmed features. It may also misread similar characters, for example 1
Original document quality directly affects accuracy. Letters which are
faint, touching or otherwise illegible may be read inaccurately.
Newspapers, copies and faxes are often poor originals.
Uneven or fast scanning, or pausing in mid-scan may result in skewed,
stretched or compressed text. Follow the tips above to avoid these causes
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