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Black-and-white scanning at 300 ppi produces the best text for conversion. At 150 ppi, OCR accuracy is slightly lower,
and more font-recognition errors occur. For text printed on colored paper, try increasing the brightness and contrast
by about 10%. If your scanner has color-filtering capability, consider using a filter or lamp that drops out the background
color.
Decreases the number of pixels in color, grayscale, and monochrome images after OCR is
Downsample Images
complete. Choose the degree of downsampling that you want to apply. Higher-numbered options do less downsam
pling, producing higher-resolution PDFs.
Correct OCR text in PDFs
When you scan to Formatted Text & Graphics output, Acrobat analyzes bitmaps of text and substitutes words and
characters for those bitmap areas. If the ideal substitution is uncertain, Acrobat marks the word as suspect. Suspects
appear in the PDF as the original bitmap of the word, but the text is included on an invisible layer behind the bitmap
of the word. This makes the word searchable even though it is displayed as a bitmap. You can accept these suspects
as they are, or you can use the TouchUp Text tool
Note: If you try to select text in a scanned PDF that does not have OCR applied, or try to perform a Read Out Loud
operation on an image file, Acrobat asks if you want to run OCR. If you click OK, the Recognize Text dialog box opens
and you can select options, which are described in detail under the previous topic.
Do one of the following:
1
• Choose Document > OCR Text Recognition > Find All OCR Suspects. All suspect words on the page are enclosed
in boxes. Click any suspect word to show the suspect text in the Find Element dialog box.
• Choose Document > OCR Text Recognition > Find First OCR Suspect.
Note: If you close the Find Element window before correcting all suspect words, you can return to the process by choosing
Document > OCR Text Recognition > Find First OCR Suspect, or by clicking any suspect word with the TouchUp Text tool.
2
In the Find option, choose OCR Suspects.
Compare the word in the Suspect text box with the actual word in the scanned document, and accept, correct, or
3
ignore the word. If the suspect was incorrectly identified as text, click the Not Text button.
Review and correct the remaining suspect words, and then close the Find Element dialog box.
4
Enable Fast Web View in a PDF
Fast Web View restructures a PDF document for page-at-a-time downloading (byte-serving) from web servers. With
Fast Web View, the web server sends only the requested page, rather than the entire PDF. This is especially important
with large documents that can take a long time to download from a server.
Check with your webmaster to make sure that the web server software you use supports page-at-a-time
downloading. To ensure that the PDF documents on your website appear in older browsers, you may also want to
create HTML links (versus ASP scripts or the POST method) to the PDF documents and use relatively short path
names (256 characters or fewer).
Verify that an existing PDF is enabled for Fast Web View
❖
Do one of the following:
• Open the PDF in Acrobat, and choose File > Properties. Look in the lower right area of the Description panel of
the dialog box for the Fast Web View setting (Yes or No).
to correct them.
ADOBE ACROBAT 3D VERSION 8
User Guide
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