KNFB Reader for iOS Complete User Guide 

Learning the Power of Your Reader

Welcome to the world of rapid, efficient text recognition and reading with our life-changing KNFB Reader iOS app. This guide will help you learn to use the KNFB Reader app on your iPhone, iPod Touch Fifth Generation, or supported iPad. KNFB Reader will enable you to read most printed documents within seconds after taking a picture.

What KNFB Reader Can Do

KNFB Reader can read a wide variety of document types you may encounter throughout the day. It performs particularly well for reading printed memos, reports, fliers, and virtually any other kind of document typically printed from a personal computer. It will also read many professionally printed items of various sizes, colors, and styles, including:

  • Books
  • Magazines
  • Most restaurant menus
  • Utility bills
  • Printed mailing addresses
  • Class or conference handouts
  • Hotel bills
  • Printed receipts
  • Airline boarding passes
  • Labels on packaged foods showing contents and nutrition information
  • Transit brochures and schedules
  • CD labels

What KNFB Reader Cannot Do

KNFB Reader has been developed to recognize and process a wide variety of type styles, printing formats, and lighting conditions. However, as computer software, the app is not quite as adaptable as the human brain.

You can expect some printed matter to be read accurately with very high reliability, but in other instances performance with a particular type of print or item may not meet your need. In general you should give KNFB Reader a try with things you need to read. This will help you to learn best what to expect.

KNFB Reader is not designed for use with handwriting or scrolling text on a screen or sign. Accuracy for household product containers (food boxes, tea bags, milk containers, detergent bottles, etc.) may vary, especially if the written information on these containers is artistically presented or is surrounded by pictures and graphics.

Other circumstances that may decrease accuracy include:

  • text printed on cylinders with warped or incomplete images (such as soup cans or medicine bottles)
  • LED and LCD screens with refreshing text (such as digital clocks, computer screens, and cell phone screens)
  • vending machine buttons and instructions
  • engraved print (such as serial numbers) on machines
  • very large printed text
  • posted signs such as signs on transit vehicles and signs in shop windows
  • conventional, analog clocks

Factors Affecting Accuracy

As with human vision, performance of KNFB Reader will vary depending on several factors, including:

  • surface reflection and glare
  • distance between the camera and the target text
  • text size and variation
  • text layout
  • curvature of the target text
  • wrinkles and creases
  • background images and colors
  • ambient lighting
  • shadows
  • obstructions (such as cords, fingers, or neckties) between the camera and the target text

Except for obstructed images, the app can generally adjust to a normal amount of variability with each of these factors. Nonetheless, some attention should be given to minimize the impact of any of these variables when getting ready to take a picture.

Take a Picture, Display and Read Text

When KNFB Reader first starts up, you will be on the Image Capture screen with VoiceOver focus on the Take Picture button. With the screen of the device facing up, place your iOS device down with the camera in the center of the document. The device should be held in the same orientation as the document — portrait orientation is recommended — and lift the device straight up approximately eight to ten inches (letter format documents) or 27 to 32 cm (A4 format documents).

Held in this position, the camera is on the underside of the device in the far right-hand corner away from you. (Check your camera periodically to make sure that the lens is clean and unobstructed). Be sure to hold the device so no portion of a finger or your hand is close enough to the camera to block the view of the document. For a normal 8.5 by 11 inch (letter format) or 21 by 29.7cm (A4 format) sheet, the camera will see the entire page at a distance of 11 to 13 inches or 27 to 32 cm.

To take a picture, touch the left side of the screen, and VoiceOver should say, “take picture.” Then you can gently double tap anywhere on the left-hand side of the screen, and the camera will respond with the distinctive sound of the shutter.

For best results, to avoid jiggling the phone while the picture is taken, try using a split tap command. To do this, place two fingers firmly on the left-hand side of the screen, and then lift one finger to snap the picture. Hold the device steady until you hear the camera shutter sound.

The image is processed for text. If any is found, the text is displayed automatically and read aloud as the Text Navigation screen opens. To pause or resume reading, double tap with two fingers together. Use the VoiceOver rotor and standard gestures to navigate through the text or additionally by using the navigation controls located at the bottom of the screen.

To save the document, activate the Save Document button located just above the recognized text in the right-hand corner of the screen. To return to Image Capture and take another picture, activate the Back button or perform the VoiceOver scrub gesture to go back.

Picture-taking Tips

Sharp pictures are essential for optimal performance. Hold the device steady by using both hands and brace your elbows on the reading surface, while keeping the device far enough from the document to capture all the text. For best results, place the text you want to read on a flat surface in front of you.

Flatten the document as much as possible. Keep the device level over the page. Fill the screen with the view of the document you want to capture.

To confirm your camera position or learn the feel of a well lined up picture, use the Field of View Report option. You can activate the Field of View Report by double tapping or split tapping the right-hand side of the screen and holding the device still to listen to the report. You can then adjust the position of the device above the page and repeat the process as needed. The goal is to have the device close to the document but still far enough away that all four edges of the document are seen by the camera.

Practice will help in the beginning. Use a familiar document printed in clear type on an 8.5 by 11 inch (letter format) or 21 by 29.7 cm (A4 format) white sheet of paper for your initial practice sessions. Place the document on a flat surface having a plain dark matte (not shiny) background. After some practice with aiming and taking pictures, you will begin to know how KNFB Reader responds. You will also be better prepared to analyze and correct conditions you can control when performance does not measure up. A little practice and persistence can greatly improve performance.

Navigation Basics

This guide will instruct you on navigating KNFB Reader on your iDevice using the built-in gesture-based screenreader called VoiceOver. An overview of how to use VoiceOver in iOS can be found at This document assumes that the user has basic knowledge of how to navigate using VoiceOver and does not serve as a replacement for VoiceOver training.

Instructions for navigating KNFB Reader may reference the following basic VoiceOver gestures:

  • Flick left/right with one finger: move backward or forward by element
  • Flick down/up with one finger: move forward or backward using the currently selected element set by the VoiceOver rotor
  • Double tap with one finger: activate the control currently in focus
  • Split tap using two fingers: placing two fingers on the screen and lifting one performs the action of a double tap
  • Flick left/right with three fingers: move forward or backward through a document by page
  • Double tap with two fingers: pause and resume speech
  • Double tap with four fingers: toggle VoiceOver help

Image Capture Screen

KNFB Reader opens to the Image Capture screen, but several other screens are also used for reading text and performing other functions in the app. Think of the image capture screen as the home screen for the app. To activate a control or to change a setting with VoiceOver enabled, double tap with one finger or use a split tap command for best results when taking pictures. The next few sections will discuss using the controls on the image capture screen in greater detail.

Screen Layout

When KNFB Reader is launched for the first time, the VoiceOver focus will be on the Take Picture button. The controls on this screen going from left to right, top to bottom in VoiceOver swipe order are as follows:

  • File Explorer
  • Settings
  • Camera Flash
  • Tilt Guidance
  • Take Picture
  • Field of View Report
  • Buy Unlimited Version (only when still in trial mode)
  • Add Picture from Library
  • Batch Mode
  • OCR Language
  • Document Type
  • Select Profile
File Explorer

The File Explorer screen is where your saved files are located. Double tap on the File Explorer button, located in the upper left-hand corner of the Image Capture screen, to access the File Explorer screen. Activate the Back button to return to the previous screen. Files are listed by date with the newest file appearing first and the oldest appearing last in the list. Use VoiceOver actions or double tap the Edit button to access additional file management-related actions including export options, renaming, and deleting saved documents. Saved documents may also be deleted using a flick up gesture followed by a double tap with the actions item selected in the VoiceOver rotor.

PDF and Image Files

PDF and JPG files may be imported in to KNFB Reader for text processing using the Open With function. This means that if you have an image-based PDF or JPG file that you know contains text, importing the file in to KNFB Reader will enable you to rapidly process the file, extract any text, and have the contents read aloud and available in Braille.

A sample workflow for extracting text from a PDF or JPG file would function as follows:

  • Navigate to a PDF or JPG email attachment.
  • Using the Share option, open the file in KNFB Reader.
  • Double tap on the imported file, and activate the Scan button to extract text to be read aloud.
Settings Button

Navigate to the Settings button by swiping right from File Explorer on the Image Capture screen. The Settings screen consists of three tabs with various controls for changing the way the app functions. Accessing specific settings in any of the tabs may be accomplished by double tapping on the desired tab to select it. To exit settings and return to the Image Capture screen, activate the Back button located on the top left of the screen.

Moving from left to right, the tabs on the settings screen are as follows:

  • General tab
  • Text tab
  • About tab
General Tab

The General Tab is divided into four types of settings: Camera, Reader, File Manager, and Dropbox Backup settings.

The Camera settings section contains two switch buttons: Flashlight Is Always on and Field of View Landscape Mode.

The Flashlight setting, when enabled, will turn on the LED light located next to the back camera, which you can use as a light source for taking pictures in the dark or in low-light conditions. Please keep in mind that when the flashlight is enabled for long periods of time, the battery may drain faster.

In the Camera settings, you also find a Select OCR Languages button. Hitting this button brings you to a new screen in which you can select or deselect the OCR languages you want KNFB Reader to offer you in the OCR-language picker on the Take Picture screen.

The Reader settings part of the General Tab contains three switch buttons: Automatically Start Reading, Allow Reading in Background, and Allow Word Highlighting.

The Automatically Start Reading button determines whether or not text will be read immediately after the image is captured and text is available. This setting is enabled by default. Disabling it will cause KNFB Reader to seem slower, since the page needs to fully process before text can be read with VoiceOver.

The Allow Reading in Background toggle determines whether or not speech stops when switching the app to standby.

The Select Reading Languages button brings you to a new screen in which you can select or deselect the reading languages you want KNFB Reader to offer you in the Document Language Picker on the Reader screen. If you find a More Info label next to a language you want to select, then you have a choice between two or more variants of that language, for instance US and UK English. Tapping the More Info label will bring you to a new screen where you can make your choice between the language variants.

In the File Explorer settings section, you will find a toggle labeled Confirm Before Deleting. When switched to "on," the system will always ask confirmation before deleting a file.

In the Dropbox Backup settings section, you will find a toggle labeled Link to Dropbox. When switching this button to "on," a Dropbox dialog will appear that asks you to allow access by KNFB Reader to the files and folders in your Dropbox. Allow access or select another Dropbox account for backup.

Once you have allowed access to the Dropbox account, all KNFB files are saved to a Dropbox folder named KNFB. You will find this folder in the root of your Dropbox folder. From now on these KNFB files on Dropbox will be synchronized with the KNFB files on your device. For instance if you add a page to a document, that page will also be added to the document in the Dropbox folder. Now you can use the Dropbox folder to retrieve individual files. To do this open your Dropbox app, go to the KNFB folder, and go to the file you want to retrieve. Select Open in KNFB Reader to retrieve the actual file. If you delete a file on your device, it will not be deleted in the Dropbox folder so that it is still there for later use.

Once you have allowed access to a Dropbox account, you will find two additional buttons: Backup All KNFB Files to Dropbox button, and Restore All KNFB Files from Dropbox.

After tapping the Backup All KNFB Files to Dropbox button, a zip file containing all KNFB files on your device is saved in the KNFB folder on Dropbox.

The backup file is used by the Restore feature to place all files back on your device. To do this, double tap on the button Restore All KNFB Files from Dropbox, and all KNFB files on your device will be deleted and replaced by the files in the backup from Dropbox.

Text Tab

The Text tab is automatically selected when you first arrive at the Settings screen.

The Text tab contains two categories of settings, which are indicated by headings, for changing the way text is displayed on the screen: Text Settings and Highlight Settings.

Text settings include

  • Font type
  • Font size
  • Text color
  • Text background color
  • Line distance

Highlight settings include

  • Highlight text color
  • Highlight background color
About Tab

The About tab is where the app version, copyright information, quick start, acknowledgements, and user guide are located.

Camera Flash—on Image Capture screen swiping right from Settings.

To take the perfect picture for optimal text results, it is important to have an adequate light. The Camera Flash control, accessed by swiping right from Settings on the Image Capture screen, can be cycled between three settings: automatic, on, and off, with on set as the default. The automatic flash setting utilizes the light sensor on the camera to determine whether additional lighting is necessary, and triggers the LED flash when the reading environment is too dark. Cycling between flash modes may provide better text results depending on the material of the document being captured. As an example, there may be instances where disabling the flash may provide better text results from a glossy brochure or computer monitor.

Tilt Guidance—on Image Capture screen swiping right Camera Flash.

The Tilt Guidance setting, accessed by swiping right from Camera Flash, is an alignment tool that can be toggled on and off to provide vibration feedback on whether the camera is being held level over a document. When this setting is enabled, your device will vibrate in Image Capture mode when the device is tilted to the left, right, front, or back. The vibration pattern pulsates when the device is not level to a desk or table. Rapid pulsing indicates more tilt right, left, front, or back; and slower pulsing indicates less tilt. No pulsing means the device is level over the document.

Take Picture Button

The Take Picture button can be found by swiping right from the Camera Flash control, or by touching anywhere on the left-hand portion of the screen and using a double tap or split tap command to take the picture. KNFB Reader has been designed to make it simple to capture images quickly and efficiently. The best images for extracting text have all four edges in the field of view of the camera. The most efficient method for accomplishing this is to lay the iDevice in the center of the document and raise it straight up approximately eight to ten inches (letter format) or 27 to 32 cm (A4 format) before taking the picture. The device can be held in landscape or portrait position relative to the document, but remember that the camera is located in the top right corner, so avoid covering it with your hand or finger.

Field of View Report

The Field of View Report button can be found by swiping right from the Take Picture control, or by touching anywhere on the right-hand portion of the screen and using a double tap or split tap to activate the report. The Field of View Report is available to help learn how best to align the camera with the document you want to read.

Use the Field of View Report button to capture an image and announce the position of your camera relative to the document. Similar to capturing an image for text reading, the camera should be centered over the print material approximately eight to ten inches (letter format) or 27 to 32 cm (A4 format) away in order to have all four edges visible in the picture. An optimal field of view report is "all four edges are visible, rotated zero degrees clockwise." This means that the entire document is visible in the frame and no text will be cut off. Practicing with the field of view report will help you get a feel for how the camera sees various document sizes and works in different lighting conditions.

Buy Unlimited Version

The Buy Unlimited Version button can be found by swiping right from the Field of View Report. This button is only displayed when you are still in trial mode. Select this button if you want the buy the full version of KNFB Reader.

Add Picture from Library

The Add Picture from Library button can be accessed by swiping right from Field of View Report or Buy Unlimited Version. This button opens the photo library on your device and allows you to select a photo. Selecting a photo opens the Recognize Imported Image screen displaying three buttons: Recognize Image, OCR Language, and Document Type. The purpose of the OCR Language button and the Document Type button is the same as on the Take Picture screen. Hit the Recognize Image button to OCR the photo
you have selected.

Batch Mode

To access Batch Mode, swipe right from the Add Picture from Library button. Using Batch Mode is one means to capture, process, and read multi-page documents as a single file. To enable Batch Mode, double tap the Batch Mode button to toggle the setting on. Once Batch Mode has been enabled, use the Take Picture button to capture each page of the document. When all pages have been captured, activate the Batch Mode control to process the images for text. Announcements will be made after each image has been successfully processed. The text will be read aloud once the last image has been processed.

OCR Language

KNFB Reader is able to recognize and read printed materials in several languages including:

  • English
  • French
  • German
  • Dutch
  • Italian
  • Spanish
  • Swedish
  • Norwegian
  • Portuguese
  • Danish
  • Finnish
  • Turkish
  • Polish

To select an alternative text recognition language, swipe right from the Batch Mode button, double tap the OCR Language button, and use the language picker to select the desired language. Double tap the Done button to return to the Image Capture screen. Please note that you can limit the number of shown languages on the picker in Settings.

Document Type

To access the Document Type button, swipe right from the OCR Language button. KNFB Reader can recognize two distinct document types. The default type is Multi Column, which recognizes single or multi-column page layouts and reads the print in the intended order. Switch the document type to Single Column for documents with information in one column relating to information in the next column beside it, such as invoices where item and price are meant to be read together. The document type options may be selected or changed by activating the Document Type control, selecting the desired item in the picker, and double tapping the Done button to return to the Image Capture screen.

Select Profile

The Select Profile button can be found by swiping right from the Document Type button on the Image Capture screen. KNFB Reader provides three modes, called profiles, for capturing images for text recognition. Use the Manual profile to take pictures with the double tap or split tap gestures. Use the Automatic profile when you want KNFB Reader to take pictures automatically when the document you want to read is properly lined up and text is detected in the frame. Use the Stand Picture mode when you want to place your device on a stand while leaving your hands free to place documents in view of the camera and turn pages.

In Automatic Picture mode, the iDevice should be centered on the document and lifted to the adequate height. Once text is detected and all four edges are in the frame, the picture will be taken and any available text will be read aloud.

In Stand Picture mode, KNFB Reader will take a picture automatically when no movement is seen by the camera and text is detected. For best results a stand with lights for the viewing area should be used. The typical workflow when using a stand is:

  • Double tap the Select Profile button.
  • Choose Stand Picture in the profile picker.
  • Tap OK on the "First place device on empty stand" message. You will get this message every time you move the device while in Stand Picture mode.
  • Make sure there is no document in the stand.
  • Place your device on the stand.
  • Tap on the OK button.
    • The camera will calibrate for best performance. This is indicated by a short double beep.
  • Once you hear this beep, you can place the document you want to read within the viewing area of the camera on the stand.
    • When the camera detects that a document is being placed in the viewing area, a continuous tone is provided to let you know that the document is being seen. This tone stops when movement stops and text has been detected.
  • After a short silence while the presence of text is confirmed, KNFB Reader will say, "Text found" as the picture is taken automatically.

Switching KNFB Reader to Batch Mode while using a stand is especially useful for capturing and reading multi-page documents such as magazines and books. With Batch Mode switched on and your device placed on a stand, approximately twelve inches from the reading surface, you can then place pages in the camera viewing area while the picture is taken automatically. Note that automatic text detection from a stand also works when flipping pages of a multi-page document placed in view of the camera as well, but be sure to hold pages down at the edge so as not to block the camera from seeing all of the text.

Reading and Text Navigation Screen

This screen is used to display and read text, highlighting each word as it is spoken. You can also navigate through the text, view or change settings relevant to text, spell words, reprocess the image, or save files. To get to this screen you must take a picture in which text is recognized, or by opening a file in File Explorer.

Screen Layout

The Reading and Text Navigation screen has several controls located above and below the document text. The controls on this screen going from left to right above and below the text in VoiceOver swipe order are as follows.

  • Back
  • Settings
  • Show Picture Associated with the Selected Page
  • Add Page to Document
  • Recognize This Page Again
  • Save Document
  • Choose TTS Language
  • Choose TTS Speech Rate
  • Navigation and Play/Pause Controls

The Settings button is located above the text on the Reading screen and can be accessed by swiping right from the Back button. Opening the Settings screen displays the same options already discussed in Settings from the Image Capture screen, noting especially the adjustments for text font, text size, text color, background color, and distance between lines. Highlight adjustments include highlight text color and highlight background color.

Show Picture Associated with Page

The Show Picture Associated with Page button can be found by swiping right from Settings on the Reading screen. Activating this control will display the original captured image.

Add Page to Document

Find this button by swiping right from the Show Picture Associated with Page button. Double tap this button if you have a multi-page document and you want all pages to be saved together in a single file. Note that you will be prompted to save the first page of a multi-page document by selecting the file name you want or just accepting the default. Then, after the first page is saved, you will be returned to the Image Capture screen to take the picture and add the second and successive pages by pressing the Add Page button on the Reading screen each time. In this way you can continue to add pages to create a single document, but to end the process the entire file must be saved again after you have added the final page.

Recognize This Page Again

Swipe right from the Add Page to Document button to find the Recognize This Page Again button. Activate this control to reprocess and read the latest image captured in a different text detection language or in the opposite document type, for example Single Column instead of Multi-Column.

Save Document

Above the text, swipe right from the Recognize This Page Again button to find the Save Document button. The text displayed on the Reading screen after you have taken a picture will be discarded unless you activate the save option before leaving that screen. Activating the Save Document button will display a dialog with a text entry field for the file name prefilled with the date and time. Text may be modified in the entry field for a file name you are more likely to recall. Double tap the Save button to confirm the process and place the file in File Explorer, reachable from the Image Capture screen.

Choose TTS Language

Choose TTS Language can be found on the Reading screen below the text. To access this button, swipe right after the last word of text. Activating this control displays a language picker where an alternative language for the reading voice can be selected. Swipe right and then double tap Done to close the language picker. Please note that you can limit the number of shown languages on the picker in Settings.

Choose TTS Speech Rate

This button can be found by swiping right from the Choose TTS Language button. This setting controls the speed at which the Reader reads text. The possible values range from 0 percent to 100 percent. Double tapping this control will display an adjustment slider for selecting the desired speech rate value.

Navigation and Play/Pause Controls

These buttons can be found below the text on the Reading screen. The text-to-speech (TTS) controls, from left to right, include Previous Sentence, Previous Element, Play/Pause, Next Element, and Next Sentence. These buttons function similar to DAISY player controls for navigating through the recognized text.

Getting Help

If you still have questions after you have studied this Guide and consulted the user list, please email a request for assistance to

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