Using knfbReader

Logo for knfbReader

The knfbReader App

Ocular Character Recognition knfbReader allows you to use your iDevice camera to take a picture of a printed page and have the contents of that page be turned into text that is read to you
Cost $99.99
Compatibility Requires iOS 7.0 or later. Compatible with iPhone, iPad, and iPod touch.
Developer Sensotec nv

How to use knfbReader

Take a picture of a printed page and have the printed text be automatically recognized by the application, turned into a text file, and read aloud!

knfbReader Walkthrough


When opening knfbReader for the first time, you’ll see the loading screen below


The knfbReader interface looks very similar to what you see when you open your camera app with some added buttons on top.

File Explorer

Back Button Returns you back to the default interface
Settings Same as below
Edit Allows users to share, rename, and delete documents in their knfbReader app. For more information, see below.
Documents List of documents in the knfbReader app.


Menu where users can choose general settings relating to the camera, reader, file explorer, and Dropbox backup and text settings such as font and highlight options. Users can see their current version, developer info, leave feedback, and restore documentation in the About tab. For more information about this area, see below.

Camera Flash Mode

Camera Flash is Automatic The knfbReader app will automatically detect if the flash is required and utilize it when needed.
Camera Flash is On The flash will be used every time you capture an image.
Camera Flash is Off The flash will never be used when capturing an image.

Tilt Guidance

Button that toggles tilt guidance mode on and off
When on, your device will vibrate when trying to capture an image if the device is not level or parallel with the document.

Take Picture

Located on the left half of the screen, the Take Picture button will capture the image of the document you’re working with.

Field of View Report

Located on the right half of the screen, the Field of View Report button will give the user feedback about how to move the iDevice to ensure better capture of the document.

Camera Roll

Allows user to open their Photos app to import photos to be processed by knfbReader

Batch Mode

Enabling batch mode will

OCR Language

Change the language between English, French, Spanish, and German

Document Type

Choose the format of the original printed page – Single column or Multi column


Manual picture Image capture requires user to manually press the Take Picture button
Automatic picture knfbReader will capture image automatically
Document Stand Mode for use with a document stand

Document Mode

Following a scan or opening a saved document, the app will bring you to the document view
Screen shot of knfbReader document reader
In this mode, users can view document image, combine, re-do OCR, save, and have documents read.
View Image Associated with Document Shows the image the OCR scan was taken from
Screen shot of knfbReader image scan
The first three items you’ll encounter in this view are the Back button, current page (ex. 1/1), and Settings
Add Page to Document Selecting this feature will bring you back to the image scan interface of knfbReader. The difference between this mode and the normal mode is that the next scan will be added as the last page of the document that was just under review.
Change Text Recognition This button allows users to have knfbReader re-do the OCR on an image with different settings. Specifically, users can change the OCR Language and the Document Type and then re-do the scan
Screen shot of knfbReader change OCR interface
Save Document Save the document
Text View The majority of the screen is taken up by the OCR generated text from the image. The “text version” of the image will appear here as simple text.
Previous Page In a multi-page document, this button will send you to the previous page
Previous Sentence In the OCR text, this button will send the focus back to the previous sentence
Play/ Pause Start and stop the reader
Next Sentence In the OCR text, this button will send the focus back to the next sentence
Next Page In a multi-page document, this button will send you to the next page
Document Language Change the language of the reader
Speed Change the speed of the reader. Note that this is not the same as the VoiceOver speech rate.
Screen shot of knfbReader reader speed change interface

VoiceOver Gestures for Navigating the knfbReader Document

Single finger Swipe Left and Right Best way to navigate through the controls of the app. It is also helpful for navigating the OCR text document. Each swipe will send you forward or back by one sentence.
The Rotor Another way to navigate the OCR text document. Options in this setting include words, characters, and lines.
Four Finger Single Tap Extremely helpful for navigating to controls in the document reader. Four finger single tap at the top half of the screen will put focus on the Back button, and a four finger tap on the lower half of the screen will put focus on the Speed button.
Two Finger Double Tap Play and pause reader

Sharing, Deleting, and Renaming Files

In File Explorer users can see the scanned documents they have created with knfbReader. Saved files will appear in the order which they were created regardless of file name. As VoiceOver users move through the files, they will hear the file name, the number of pages, and the date the file was created.
Selecting the Edit button will enable the editing mode. In this mode, users can select single files to rename or select multiple files to share or delete.
Screen shot of knfbReade file explorer in edit mode
Selecting Share will bring users to menu that asks them to choose a file type from a list that includes: knfb file (.knfb), plain text file (.txt), plain text file (.rft), and formatted text file (.html).
Screen shot of knfbReader file share menu
Once users select a desired file type, an iOS pop-up message will appear with options for how the document will be shared. What apps appear here depends on the user’s device. The Message and Mail apps are both in this list, so documents can be sent via either of these apps.
Screen shot of knfbReader file share destination menu


General Tab


Flashlight is Always On Toggle on/off this setting which leaves the your flashlight on when taking images for this app.
Field of View Landscape Mode Enables better OCR for images taken in landscape orientation
Field of View Reports Visible Corners Toggles on/off whether or not visible corners are reported on in the Field of View Report
Select Recognition Language Allows users to add and remove recognition languages from the list of OCR languages


Automatically Start Reading Toggles on/off the feature that automatically has the reader begin with a newly scanned page
Allow Reading in Background Toggles on/off the functionality of the reader continuing in the background even after leaving the knfbReader app
Allow Word Highlighting Toggles on/off word highlighting
Speech Volume Change the volume of the reader
Speech Rate Change the speech rate
Select Reading Language Allows users to add and remove reading languages from the list of document languages

File Explorer

Confirm Before Deleting Toggles on/off the Are you sure you want to delete this file? message that comes up upon deleting a file

Dropbox Backup

Link to Dropbox Enable a link between your knfbReader app and a Dropbox account. Selecting this button will bring up a login window for Dropbox (see below):
Screen shot of knfbReader Dropbox login
Allow Mobile Data for Dropbox Allow file synchronization with Dropbox to utilize mobile data
Backup All KNFB Files to Dropbox Initiate a backup of all files currently in your knfbReader app on your Dropbox account
Restore All KNFB Files from Dropbox Restore all your files from your Dropbox account on your knfbReader app (replace the files on your knfbReader with the files on your knfbReader files on Dropbox)

Text Tab

Text Settings

Font Type Choose font text from Academy Engraved LET to Zapfino
Font Size Choose from 12 pt to 42 pt font
Text Color Choose a color for your text – see below
Screen shot of knfbReader font color options
Text Background Color Choose a color for the background of text
Line Distance Customize the distance between lines

Highlight Settings

Highlight Text Color Set a custom color for highlighted text
Highlight Background Color Set a custom color for the background of highlighted text

About Tab

Version The current version of your knfbReader app
Copyright Statement Statement that Sensotec NV and KNFB Reader, LCC own the rights to the knfbReader app
Company Partners List of company partners (ex. Dropbox)
Leave feedback Activating this button will open the mail app with a new, blank message addressed to with the subject line KNFB Reader feedback
Restore Documentation Use this function if you accidentally deleted or altered the Quick Start Guide or the User Guide and would like to restore them.

Training Resources for knfbReader

Hadley School for the Blind: iFocus Using the KNFB-Reader

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