Sometimes when you are surfing net you may come across some images with quotes or images related to your search query and sometimes you may download pdf files which are read only. Many people want to extract text from those images or pdf files.
OCR(Optical Character Recognition) is used to convert images or scanned copies of books into editable text. There are many free OCR(optical character recognition) tools available in online. Following are few free OCR tools.
Part1: Online OCR software
Online OCR software is available through the web browser and you don’t have to install new software on your computer. All you need is to get the image file using scanner or a digital photo camera, upload it through the online OCR web page and wait for the processed file to download.
1. Google Docs
If you have a Gmail or other Google account you might tryGoogle Docs first. Google Docs is not a dedicated OCR tool but it provides the OCR power Google uses to digitize books and process PDFs for their search engine.
To get text from image or PDF files you need to first upload and convert the files to Google Docs. Then you can do the further editing online or/and download it back as PDF, DOC, TXT etc.
In Google Docs to upload the files first you need to click Upload button, select Settings from the menu and check ‘Convert uploaded files to Google docs format’ and ‘Convert text from uploaded PDF and images files’ and then click Upload/Files.Another way is to check ‘Confirm settings before each upload’after clicking Upload/Settings so that every time you upload a file it is asked whether you want to convert the file or leave it intact. This gives also an option to select which language dictionary will be used in the text recognition process. The file is therefore converted to Google Docs document having both original image(s) and converted text in it. You can review the text and delete the original images afterwards.
Google Docs conversion works pretty good, especially with English texts. Over 30 different languages can be selected but if your language is not included in the list, the conversion may give an error and the file will not be processed. Of course – if you don’t have a Google account you can create one any time.
Input image file types: most bitmap formats
Input PDF files: yes
Output file types: ODT, PDF, TXT, RTF, DOC, HTML
Languages: 30+
Google Docs / PROS:
CONS:
Unlimited processing capacity
Text in some minor languages may not be recognized
2. Free Online OCR
Free online OCR web page is more thoroughly reviewed infreewaregenius.com.
Input image file types: GIF, BMP, JPEG, TIFF, PNG
Input PDF files: yes
Output file types: DOC, PDF, RTF, TXT
Languages: English dictionary only
Free Online OCR / PROS:
CONS:
No capacity limits for processing
Keeps original formatting and Layout
Only English dictionary supported. Text in other languages may be not recognized
3. i2OCR
Input image file types: TIF, JPEG, PNG, BMP, GIF, PBM, PGM, PPM
Input PDF files: no
Output file types: TXT
languages: 30+
i2OCR/ PROS:
CONS:
No limits for uploading
Has a review option after character recognition – the original image and result text is shown side-by-side on screen.
Only text output, all the original formatting will be lost. Though at least it supports multi column pages correctly.
Creates “hard” linebreaks at the end of each line.
Does not process PDF files.
4. OCRonline
Input image file types: JPG, TIFF, PNG, GIF
Input PDF files: yes
Output file types: TXT, PDF, RTF, DOC
Languages: 150+
OCRonline/ PROS:
CONS:
Excellent recognition quality
Rebuilds original formatting
Impressive list of 150 language dictionaries
Limited upload capacity – 5 pages in a week, file size up to 10 MB. Need to pay to get extra pages.
5. Online OCR
Input image file types: JPG, JPEG, BMP, TIFF, GIF
Input PDF files: only for registered users
Output file types: DOC, XLS, TXT (+ PDF for registered users)
Languages: 30+
Note: There is registered and guest mode available for this site. In guest mode 15 images per hour can be processed and maximum file size is 4 MB. There are some extra possibilities in registered mode, like uploading larger images, ZIP archives and multi-page PDFs. Initial credits after registering is for converting 20 pages.
Part2: Desktop OCR software
Desktop software you need to download and install to your computer, and they usually have more configurable options than online tools. Some programs include the ability to acquire image directly from a scanner so you don’t need to use other programs to do that.
The following OCR software will be reviewed: Cuneiform, OpenOCR, FreeOCR, gImageReader, Puma.NET and SimpleOCR. There are some more free tools available, which are mainly meant for more specific tasks. JOCR is for getting text from screenshots, requires Microsoft Office 2003 or later to be installed and has been previously reviewed here. Also there is Nuance PDF Reader that is able to upload scanned PDFs to its online service for character recognition. Nuance PDF Reader is previously reviewed here. And finally, there is MyMorph, a program intended for converting document archive files from one format to another, like TIFF, PDF, RTF etc. MyMorph is able to convert image files to editable text files.
6. Cuneiform OpenOCR
OpenOCR is based on commercial product Cuneiform that was released as freeware on 2007.
License: freeware
Input image: most bitmap file formats
Input PDF: no
Scanner input: yes
Output: TXT, RTF, HTML + output to Word/Excel
Dictionary languages: 20+
Cuneiform OpenOCR / PROS:
CONS:
Includes both single file and batch of files processing mode.
Installation program creates invalid start menu shortcuts like NewFolder1
7. FreeOCR
This is another of the programs that uses the open source Tesseract OCR engine. Tesseract was originally developed by HP and is currently sponsored by Google.
License: freeware
Requires: Microsoft .NET
Input image: TIFF, multi-page TIFF
Input PDF: yes
Scanner input: yes
Output: TXT
Dictionary languages: 9
FreeOCR / PROS:
CONS:
Tesseract OCR engine has good accuracy.
Only text output, no formatting recognition
No multi-column support (must crop the image manually to one column)
8. gImageReader
gImageReader is one of the front-ends to the free Tesseract OCR engine. You need to download and install Tesseract separately from this page. Tesseract engine uses OpenOffice dictionaries and spellcheckers that can be downloaded from here.
License: freeware (GNU)
Requires: Tesseract, need to download separately
Input PDF: yes
Dictionary languages: many, uses freely downloadable OpenOffice spellcheckers
Scanner input: yes
Input image: JPEG, GIF, PNG, TIFF
Output: TXT
gImageReader / PROS:
CONS:
Tesseract OCR engine has good accuracy
OCR area(s) can be manually selected
Only text output, no formatting recognition
9. Puma.NET
Puma.NET is actually not a user solution but a development kit based on CuneiForm OCR engine, though it contains a sample program with the front-end.
After installing there will be no launch icon in Start Menu but you can find the program Puma.Net.Sample.exe deep in the C:\ Program Files\ Puma.NET\ Sample\ bin\ x86\ Debug\folder.
License: freeware (BSD)
Requires: Microsoft .NET
Input image: BMP, GIF, EXIG, JPG, PNG and TIFF
Input PDF: no
Scanner input: no
Output: TXT, RTF, HTML
Dictionary languages: 27
Puma.NET / PROS:
CONS:
Font and formatting detection
You have to create the shortcut to start the program by yourself
Leaves “hard” linebreaks
10. SimpleOCR
SimpleOCR uses its own OCR engine that is capable of learning the fonts in a particular document.
License: free for all non-commercial purposes
Input image: TIFF, JPG, BMP
Input PDF: no
Scanner input: yes
Output: DOC, TXT
Dictionary languages: 3
Note: SimpleOCR seems to give better results from color JPEGs, not grayscale.
SimpleOCR / PROS:
CONS:
Word by word text revision
Ability to train the engine to use specific fonts
Includes both single file and batch of files processing mode
Only 3 languages dictionary.
No font and format detection
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