DLReader User Manual
Contents
1. v DATALOGIC DLReader User s Manual v DALALOCIC Datalogic Automation S r l Via Lavino 265 40050 Monte S Pietro Bologna Italy DL Reader User s Manual Ed 09 2011 2011 Datalogic Automation S r l ALL RIGHTS RESERVED Protected to the fullest extent under U S and international laws Copying or altering of this document is prohibited without express written consent from Datalogic Automation S r l Datalogic and the Datalogic logo are registered trademarks of Datalogic S p A in many countries including the U S A and the E U Matrix 210 Matrix 410 ID NET VisiSet and X PRESS are trademarks of Datalogic Automation S r l All other brand and product names mentioned herein are for identification purposes only and may be trademarks or registered trademarks of their respective owners Datalogic shall not be liable for technical or editorial errors or omissions contained herein nor for incidental or consequential damages resulting from the use of this material 13 09 11 CONTENTS 0 N oe LI LI lI lI Ll l3 Ll Ll Ll Ll ee mM 22 OWDANANRWWWWHND NNNNNN Nanna gj N BASIC USE OF DLREADER 3 ctae ou oce HERE RI LE EEUR ERO Ere nenna nnne 5 Loading an Mage messe e a T 5 eain ER mn TR 5 OCR Configuration Parameters Setup cccccccccccsececeeeceeeeceseesecessuseseeeeaeesaeesaeeeaes 7 Standard COMnmOUratiOn P EUN T Automatic CONTIGUEATION seseriai a E a e2. Fielding Training Font File Ima Percent Aspect Change Es Spacing Miscellaneous Minimum Char width D Horizontal Vertical Min Gap 1 Masimum Char width 999 1 acceptancelan UU Minimum Char Height Alternate Classifier Sub Char Use Alt Score o Maximum Character Height E 33 Contig Number Minimum Fisela in Object 20 OK Continue on Fail hi aximum Fisela in Object 1 DODOODU Cancel Link Char Pos 1 Variable Split None bd List Posh Discard Oversize Objects Discard Undersize Objects Char Constants Score D Sus Salle NN By default horizontal spacing has a value of one 1 and vertical spacing has a value of zero 0 When working with any character or object that consists of more than one piece it may be necessary to adjust one or both of these values Spacing Horizontal Spacing defines how far apart dots or pieces of a character can be located This value is in pixels and is in the horizontal direction only If the value is too small not all parts of a character or object will be included If the value is too large adjacent characters or objects may be included The spacing value must not be greater than the smallest distance between characters This restriction may be ignored when using the Max Width parameter Vertical Spacing is the same as horizontal spacing except in the vertical direction Unlike horizontal spacing the default and minimum valu
3. 2 or 3 while skipping any others 24 DLREADER PARAMETERS 2 5 TRAINING Reader Threshold Fielding Training Font File Ima Enable Training Once the characters or objects have been extracted with one bounding box for each character the next logical step is training Training the DLReader is very straightforward although enabling the training feature is a little more complex Enable Training Click on the Enable Training check box on the Training tab page Click on the Read Image button on the toolbar or select OCR Read in the OCR menu to bring up the training dialog box and type in one character for each object 2 6 FONT FILE AND FONT LIST EDITOR It is important to understand how the DL Reader stores and uses trained characters Unlike most other OCR readers the DLReader stores data for every character trained It is therefore unnecessary and counterproductive to train the same character from the same image more than once When done the identical character data is saved adding to storage requirements while slowing read performance In memory a list of all trained character data is maintained in the order in which it was trained When the DLReader attempts to read an object every trained character is compared against the unknown object Therefore the longer the list of trained characters the more the time needed to return the result While there is a small penalty in time for this approach a wide variety of
4. O in an aspect ratio independent manner The answer to both questions is that there is no difference 2 1 2 Character Size and Character Spacing The ideal range in height is from 25 pixels to 40 pixels Smaller characters require more training due to the limited amount of data This causes small object changes to have a large impact on the stored data thus making them harder to interpret Characters taller than 40 pixels do not add any additional data that would be beneficial in matching objects Larger objects also have the side effect of being slower to read due only to their size As long as characters are at least one 1 pixel apart in the horizontal direction spacing is generally not a factor Only if the spacing is quite large does it start to impact the performance Remember the DLReader must check every pixel after the last object in order to find the next object The larger the spacing and or the taller the ROI the greater the number of pixels to be checked The greater the number of pixels to be checked the more time that is required to process Character size font list length character spacing and number of objects all contribute to the total processing time Proper training is a key component in ensuring the minimum number of trained characters in the list 2 1 3 Character Scoring When any object is read a score is calculated based upon how well that object conforms to the object it was matched against A perfect
5. Selects what kind of image data gray scale or color is to be used ONLY GRAY SCALE Enabled IS ALLOWED Color Plane Used to select appropriate color for reading NOT USED Edge Width Number of consecutive pixels within the threshold range that define a valid edge NOT USED Match String String that the OCR check after reading Auto Rotate When checked the SW tests both the position Angle and Angle 180 Angle Ordinal position of the object 0 90 180 or 270 degrees 28 DLREADER PARAMETERS Warn Warning Quality Level 1 1000 If it s value is meaningful not 0 the OCR library raises a WARNING error that can be used inside the MATRIX application to warn the user about the decreasing quality Fail Failure Quality Level 1 1000 If its value is O default the char s scoring is controlled only by the acceptance value 2 8 AUTO CONFIGURATION In most cases Auto Configuration works well for setting object parameters however in some cases it may return erroneous data Auto Configuration will affect Reader tab page options Image Options OCY Options Auto Configuration Configuration Results Number of Objects Configure Horizontal Spacing Inter character gap Xm Mie Update Settings Charwdith oF 999 z SU Iw Height idth Char Height 333 Close Configure Auto Configuration is a method of obtaining a starting point for setting the parameters for the size and spacing of objects that will be se
6. 70047777 1 EE Summary 20047772 13 1 10 ACCEPTANCE FAIL AND WARN QUALITY LEVEL Fielding Training Font File Image Options ocv Opts Reader Threshold Fielding Training Font File Ims gt Spacing Miscellaneous M Auto Light Dark r Color Plane Horizontal Vertical Min Gap Light Characters TER 2 i i Gray Scale Alternate Classifier Sub Char Edge Width 1 Use Alt Score Match Sting 0 Contig Number Q Continue an Fail Rotation Link Char Pos fil EB Auto Rotate ve Angle Fail 0 None List Pos Char Constant Score 1l O00 16 BASIC USE OF DLREADER lt D Acceptance Typical values range from 60 75 The minimum value is 1 The maximum value is 100 The value 0 implies a special use of ROI as a locator If the Fail parameter is not set Fail default is 0 it is the only cause that make a char not recognized Fail Fail is the parameter defining the required quality level acceptable in character recognition Typical values range from 700 1000 The minimum value is 1 The maximum value is 1000 When the Font train runs it is good to set it to 900 If it s value is not 0 the char s score is compared with this value and an error char is returned instead of the recognized char if the score is lower Warning Warn parameter defines a second level of quality level in character recognition Typical values range from 700 1000 The
7. T Advanced ContlgilballOE ed cce odi e O 8 FO Ur ANNA UNG acted ac eee MET 9 Unrecognized Character Sub Char sissors ie raa a LO 11 FontTfraimingtospeed Up OCR anani mn E 11 Train Patterhs sosirii a n a o a ia ai 12 Copy Mahe d FONT rena a A A E E TA 13 Sample of Support Font Files in the File SySteEM ccceccceecseeeeeeeeeeeeeeteeeeeeeaeenes 14 Matem SAVING eite rH EE 15 Acceptance Fail and Warn Quality Level eeseeeeeseeeseeeeeenne 16 Constraints on the OCR Configuration eeseesseesseesseee eene 17 DEREADER PARAMETERS it cia cise edie eect ences ces eee edere 18 Reader and Character Constraints ccccscccsseccececeeceseecneceusecaeeceueeceeseueenaeessuss 18 Aspect Ratio IndepetideriCe us dud cce e valete ket e Po De rat e ua x Rr E x a en v URN 21 Character Size and Character Spacing cccccccceeccsecececceeeeeeeeeceuceseeceeeesueesseeeaaess 21 Charade SCORING RR EI m om 21 Uie 22 OV ODIO NOT qii eomm tantu mte desperudiiutdutuoo mu eee ere 23 Felding NOT USED i25 hat see rir a teste eee 24 Tra O iares Sees aercha PVP 25 PONT ENC ANG Font RISE Edt sci TE 25 AGC ODIO RE TRE EE DOR 28 Alto COMMOUF ANON ace etse tasto tu moo ode udo ettet best cca E 29 Saving and Restoring Reader SettingS c cccccccccseccceeeceeeseeeeseeeseeeeseeeseueeseeeseeeess 30 Chandio Mages ossee e D Ems 30 EDGE FINDERS i
8. minimum value is 1 The maximum value is 1000 It is usually greater than the Fail value If it s value is not 0 the char s score is compared with this value and a warning error is returned by the library to the application SW if the score is lower 1 11 CONSTRAINTS ON THE OCR CONFIGURATION The characters of the string to be recognized must have an average height in the range 28 45 of pixels Characters are allowed above or below average height but the reliability and recognition times are not optimal After running the Font train on DLReader the font can be controlled by pressing the Edit button in the Font File tab The Font List Editor opens Pressing First Char and then Next Char until the end of the Fonts you can see the image of the character training Synthetic Image its name Name and its dimensions of height and width in pixels Height Width In this way you can verify if the height of the characters is in the required range Reader Threshald Fielding Training Font File Ime ME Lage Eo Synthetic Image Font List Editor E I Height 42 First Char Delete Char Name Width 28 Next Char Hename Char IA Name H Seed Purge List Golden Character E Read 5 E dit ae ae E Resize Font m be E Match Count 2 Clear Lists 17 c DLREADER USER S MANUAL 2 DLREADER PARAMETERS 2 1 READER AND CHARACTER CONSTRAINTS Character 5ize Constraints Header Threshold
9. reader Changes to the size shape and position of a reader s ROI will be reflected in every ROI that is linked to it This is advantageous when the settings are used on a new image where the position of the character string is different and the ROI s must be relocated The linking tool is useful with the searching feature to be discussed later Character Constraint Parameters Percent Aspect Change Internally the reader is totally size and aspect ratio independent This means that changes in height and or width regardless of amount have little or no impact on the ability to classify characters As a practical matter however it is desirable and sometimes necessary to limit the amount of variation allowed By default this is set to 40096 This means a newly found objects must have a height or a width within a range of one quarter 1 4 to four 4 times the size of the stored trained character it is being compared against If the newly found object is outside of these limits no comparison to that trained character is done 19 c DLREADER USER S MANUAL Two primary benefits occur when setting this value First reader accuracy is improved because only objects of similar height and width are used for classification Secondly speed is improved because potentially fewer trained characters are used for classification Minimum Char Width Setting the minimum character width enables the reader to discard any found object which has a widt
10. Integer range is not checked the Floating Point calculation is enabled Outline Char NOT USED Gain amp Offset As a general rule it is better to try each of the automatic threshold methods before adjusting gain and offset There is no time penalty for adjusting gain or offset The calculation is made every time the threshold is computed Gain and offset is used is those special situations where the automatic thresholding algorithm does not correctly segment characters The gain and offset are applied according to the following formula New threshold Calculated threshold gain offset In most cases the offset is left at zero 2 3 OCV OPTION NOT USED Training Fant File Image Options OCW Options Aut 4 Enable OCY Features This option is ignored 23 c DLREADER USER S MANUAL 2 4 FIELDING NOT USED Reader Threshold Fielding Training Font File Imz 4 Ma of Positions 1 Insert String t nsert After Field String Restriction Line Humber il Character Position NE String List ALL CHARACTERS v Enable String Fielding Duplicate Close Fielding is a means to restrict the trained font list by object position Fielding can be used to improve accuracy and speed For example if it is known that object position one can only contain a number fielding can be used to tell the reader to use only numbers when attempting to match an object This is especially important when using n
11. arched for in the character recognition process For any given ROI Auto Configuration will determine the number of characters in the string the horizontal spacing and the inter character gap It will also compute the minimum and maximum character widths and heights These values are all reported in the Auto Configuration tab page when an ROI box has been placed tightly around an object string and the Configure button has been pushed Number of Objects Auto Configuration will return the number of objects found in the string if the read takes place successfully Horizontal Spacing Horizontal spacing is a pixel value and defines how far apart dots or pieces of a character can be located The Configure function returns this value Inter Character Gap This value is the minimum horizontal spacing between adjacent characters The default value is one 1 and is retuned by the Configure function 29 c DLREADER USER S MANUAL Char Width Minimum and maximum values for character width are returned by the Configure function Char Height Minimum and maximum values for character height are returned by the Configure function 2 9 SAVING AND RESTORING READER SETTINGS The entire setup including the position shape and size of the ROI can be saved for later use This is useful for sharing the information or simply performing a read operation on an image at a later time To save an image click on the Save Readers button on the toolbar or sel
12. button to remove the object from the list Rename Char To rename the object change the name in the Name edit box and click the Rename button Purge List Erase all the trained Font Resize Font Changes the trained Font dimension in order to fit a new Application constrain without re train the Font Clear Lists Reset the counter that scroll through the list to find the object Golden Character If more than one instance of the same object with the same Name is trained one of them can be chosen as Golden in this case the score of the recognized Label is calculated against the golden char even if it has matched best another instance Use Golden Char Enables the use of the configured Golden Chars 27 c DLREADER USER S MANUAL 2 7 IMAGE OPTION The Image Option tab page allows the operator to set a number of parameters with respect to the image involved in the search Fielding Training Font File Image Options DCv Opt Auto Light Dark Color Plane Light Characters Iv Gray Scale Edge Width Match String Rotation Auto Rotate Anale 0 Warn E Fail lose Luminance Auto Light Dark This option will automatically determine if the objects are light on dark background or dark on light background If checked this option will be invoked on every read Light Characters In the manual mode the option will set light characters In the automatic mode it will be used as feedback Gray Scale Image
13. e is zero 0 Rather than mean no adjacent objects in the vertical direction zero 0 means ALL objects in the vertical direction With proper location of the ROI and selection of thresholding type zero 0 will usually provide the best results Non zero values must be used with caution with dot matrix characters The underlying algorithm uses this parameter to discard extraneous data above and below characters which in turn may cause the DLReader to ignore valid dot matrix objects It is generally recommended to use Max Character Height see Char Constraints tab rather than using a vertical spacing value other than zero 0 Min Gap This defines the minimum horizontal spacing between adjacent characters When set the DLReader skips over this number of pixels before starting its search for the next character The default value is one 1 Setting the minimum gap can improve performance times especially when the spacing between objects is very large 18 DLREADER PARAMETERS Acceptance When comparing an object against objects in the font list the acceptance value is used as a low end cut off parameter by the internal algorithms The range for the majority of applications is between 60 and 75 when using the relaxed mode The values may be a little lower when not using the relaxed mode For applications concerned with both reading and quality of marking the acceptance should be set between 75 and 85 In addition only high qualit
14. ect Save Reader Data from the OCR menu Enter a file name in the dialog box and click Save The parameters that are saved are identified by the checkboxes on the Save Options tab page oaved settings can easily be restored Once the DLReader is started and an image is opened it is not necessary to create a reader if saved settings are to be restored Click on the Restore Readers button on the toolbar or select Restore Reader Data from the OCR menu to restore the saved reader s It must be remembered that the font file will be saved in the location indicated on the Font File tab page If the information is shared with another computer the file must be in that location for the DLReader to find the file Saved readers can be restored at any time They will replace any reader or readers that may be in use at the time of restoration If a reader is restored and the settings are changed it is easy to return to the original saved settings Simply restore the saved reader 2 10 CHANGING IMAGES When using the DLReader there are three 3 ways to change the images close the image replace the image or run a sequence of images In order for the DLReader to operate it is necessary to have an open image Closing the active image closes all readers and all the unsaved setting information is lost If the active image is the only open image the DLReader is returned to its original state To use the reader or readers on a new image the original image m
15. h less than this value This is true regardless of any other settings Maximum Char Width Maximum character width defines the maximum bounding box width If the Variable Split checkbox is unchecked this is a hard number That is all objects that potentially could be wider are set to this width If the Variable Split checkbox is checked then the maximum width can vary slightly when the reader selects the optimal split column If the Discard Oversize Objects checkbox is checked any object wider than this value is discarded and not used for classification Minimum Char Height As it implies this sets the minimum height that any character can be Unlike Minimum Character Width character heights are adjusted upward if the newly found object is too short Adjustments are automatic Maximum Char Height Objects that are too tall can be automatically resized by setting this value If the Discard Oversize Objects checkbox is checked any object taller than this value is discarded and not used for classification Minimum Pixel in Object This defines the minimum number of pixels within the threshold range that an object must contain If the object has fewer pixels than this value it is discarded and not used for classification Maximum Pixel in Object This defines the maximum number of pixels within the threshold range that an object must contain If the object has a greater number of pixels than this value it is discarded and not used fo
16. he only supported Edge ROls are rectangular and can be configured to find only horizontal vertical edges 32 EDGE FINDERS D 3 2 FINDING THE EDGE The first step in finding the edge is determining which edge is to be used Selecting the Side radio button will determine how the search for the edge will be conducted For example choosing the Right side will cause the program to start from the right hand side of the ROI and search to the left for an edge The Transition control allows the choice of a transition from light to dark dark to light or any edge transition 3 3 OUTPUT INFORMATION SHOWN ONLY GRAPHICALLY The Edge Finder gives information to the user that can help with setting up an OCR application that might use this tool The Center Edge gives the center location of the found edge as the name would indicate This value is not updated in the DLReader Edge window but it is only shown in the Edge ROI The Time is the reading time of the Edge Finder 33 www automation datalogic com
17. ight ELEN Minimum Fisela in Object 20 ok Reader Threshold Fielding ene Font File Imes E E Sub Char Horizontal racing Vertical 1 0 T Alternate Classifier Use Alt Score Contig Number Continue on Fail Link Mone Char Constraints B Char Pos ia List Pos Score D Maximum Pirels in Object 1 oo0000 Cancel Variable Split Discard Oversize Objects Discard Undersize Objects BASIC USE OF DLREADER Fielding Training Font File Image Options ocv pt Reader Threshold Fielding Training Font File Ime Ji Autolight Dark p Color Plane Type d r Threshold Values Light Characters Luminance Computed Low High Luminance comp Iv Gray Scale Linear 0 88 z Non Linear Edge width Black Size fa Match String Rotation Gain 1 000 Auto Rotate Angle 0 T warn Fait 0 Cloze Using these parameters has a direct effect NEGATIVE on the computing time and the scaling capacity of the OCR One possible segmentation of the t and z is shown in the picture but it is not very 2658 Wetzikon 1 4 FONT TRAINING Once a correct segmentation of the characters has been made you have to run font train You must put a checkmark in the Enable Training box on the Training tab in the configuration window Press the OCR button of the DLReader This opens a pop up
18. lete the names of the various Font File tabs so the font is copied from RAM Note This process can be very useful when creating the Font if you want to use multiple readers to create a single Font The file Name is then used as partial support of the Font 1 8 1 Sample of Support Font Files in the File System e 2 sd TL 32 ie j E l d phi TE ees EXER ANTE hon A es 4 x aso uc L fuge A SIUE n DN M r amp E To make a complete train of the alphabet from A to Z AND use it the ROI in both there are two methods METHOD 1 Create a Reader AM make the Font train ABCDEFGHIJKLM move the ROI AM down make the Font train NOPQRSTUVWXYZ 14 BASIC USE OF DLREADER e then follow the method above to create the NZ reader and associate it with the same AM font o Inthe AM Font Files tab Write a name in the Name line eg myFont SAVE and run a READ o Create a new NZ reader Copy the parameters of the AM reader in NZ METHOD 2 e Create the AM Reader make the Font train ABCDEFGHIJKLM e Inthe AM Font Files tab Write a name in the Name line eg myFont SAVE and run a READ e Create an NZ reader Copy the parameters of the AM reader in NZ Make the Font train NOPQRSTUVWXYZ SAVE and run a READ e Reopen the AM and run a READ to update your Font with the new characters 1 9 MATCH STRING An expected string can be configured if it is known Fielding Training Fon
19. nea ence eee te eee 32 GREATING an EDGE Ili eei iota te acti deel tates one aet de sades 32 miseluspu due ec o 33 Output Information shown only graphically ccccccceeccsececeeeeeeeeceeeseeeeeeeeseeeeseeees 33 BASIC USE OF DLREADER lt D 1 BASIC USE OF DLREADER 1 1 LOADING AN IMAGE The command File gt Open loads the bitmap EReader PESE mim view Help Open Ciro ar zl H d m E 1 imgi bmp z2 C MyTESTyedgedet imgl bmp 301 MYTESTYzDbcoderat imgl bmp 4C MyTESTYautorok img bmp Exit Open an existing document 1 2 CREATING A ROI With the command OCR gt New Reader a generic ROI is created The user is prompted to choose a name unique to give to the ROI The user s needs to correctly position it on the string to be recognized NOTE The ROI cannot contain strings placed on multiple lines if more lines should be read a new ROI should be created for each line The ROI is better if it contains only the string to be read to avoid parts of other strings or parts of designs If the ROI contains strings on the same line separated by spaces the spaces will be ignored and the strings will be concatenated into a single output This should create a number of ROI equal to the number of strings to be read even if they are on the same line The only supported ROIs are rectangular and can be configured to find only horizontal vertical stri
20. ngs DLREADER USER S MANUAL RA Reader ime bmp Sel EH UD Ea Ma Re Open Reader Tab Box E imgi bmp Save Reader Data Restore Reader Data Delete Reader OCR Read Copy Reader Settings Sequence Configure 4 new reader In addition to the rectangle to be positioned it also opens a configuration window Reader Threshold Fielding Training Font File Ime Spacing Miscellaneous Horizontal Vertical Min G apt am jo Aeceptance En Altemate Classifier SubChar s Use Alt Score Contig Number 0 Continue on Fail Link Char Pas m None l List Pos Char Constan Score T BASIC USE OF DLREADER 1 3 OCR CONFIGURATION PARAMETERS SETUP File View Window Ocr Help Ee fe eee ee eee E img1 bmp There are three configuration levels of the character segmentation Standard Configuration this is the first to be tried It works well if the characters are sufficiently separated and the contrast is good Automatic Configuration this is the second to be tried and solves many types of difficult applications Advanced Configuration this requires a thorough knowledge of the DLReader tool Please refer to the documentation included with the tool Each time you press the button Ea the segmentation of the characters on the configuration chosen is highlighted in the selected ROI 1 3 1 Standard Configuration For a ROI like the one in the figure the standa
21. nt was being used with the presently open Reader it may be desirable to delete the font file in memory so that it has no effect on the accuracy or speed Clicking the Yes button in the inquiry box when it appears does this Save After clicking on the Save button an inquiry box will appear asking whether or not to delete the font file in memory Clicking on Yes will erase the trained font from the volatile memory of the computer allowing the user to train a different font file without changing the settings on the Reader This could be used if the image contained the entire list of characters for a particular font The entire list could be trained and saved then perhaps just the numbers could be trained for applications where only numbers are to be read and speed is essential Edit If a mistake is made during the training process the font list can be edited to either delete or rename any stored object Open the font editor by clicking on the Edit button on the Font File tab page 26 DLREADER PARAMETERS Font List Editor Parameters This window can also be used to obtain the height and width of each object in the font list Name Label associated with the trained object First Char To rename or delete an object click on the First Char button to start the font list the image of the trained object will appear Delete Char Click the Next Char button to scroll through the list to find the object Next Char Then click the Delete
22. on OCR font styles or reading degraded characters Fielding can also serve to stop the reader when the Maximum Number of Characters is reached In situations where the region of interest may include noise or artifacts to the right of the objects this will reduce or eliminate the number of failed reads due to the inclusion of that artifact The Line Number fielding parameter restricts the search to a particular line number in a multiple read situation As the above figure shows any position can be restricted to any one of the options of the String List ALL CHARACTERS ALPHANUMERIC ALPHA ONLY NUMERIC ONLY HEXIDECIMAL SPACE FORCED CHAR NON ALPHANUMERIC USER PATTERN 1 Letter of Month 2 Letter of Month 3 Letter of Month Most are self explanatory The Space option forces a space in the specified character position This would be used to ignore a character The Force Character option works similarly to the Space option in that it ignores the character in a specified position but instead of a space it puts a user specified character in that position The option entitled User can be very useful in some situations For example if the ROI contains a numeric day of the month the first position can be restricted to just O 1 2 or 3 Position two will be restricted to the Numeric setting By setting the field restrictions in this fashion position one objects will only be compared to trained characters with the identifiers of 0 1
23. ossible to train the entire pattern using the special char before and after Train Text 1 BOM min Enter the string characters or the substitution character for any unkown aor invalid objects Train Rotated Cancel 12 BASIC USE OF DLREADER OCR Read Results model bmp Dutput PASS 150 HM min mum Lina 150 M min There is a fast way to use the same font on multiple rows without having to train it again In general this operation is not recommended because it is better to train the font for each line but is still useful to know how it works Suppose you have trained a complete font for line 2 reader row2 Now you may use the same font for line 3 The steps are as follows In the Font Files tab of Row2 M ame mFont write a name on the Name line eg myFont then SAVE When prompted Delete font file in memory press Yes then run a READ When asked Delete font file in memory press Yes 13 DLREADER USER S MANUAL Create a new reader Row3 Reader ID ID Row3 Cancel Selecting the new reader Row3 copy the parameters of reader Row2 by pressing the appropriate key Copy reader setting Choose row2 as the reader to be copied File View Window Ocr Help Reader List Header row2 Cancel In the Font Files tab of Row3 make sure that there is the same name used in row2 Name row eg myFont Before saving the DLR file you can de
24. r classification Variable Split When checked this enables an intelligent algorithm to look back a few pixels to identify the optimal split point between characters Note This is not recommended for widely spaced cleanly printed dot matrix characters Discard Oversize Objects When this flag is set objects that exceed the maximum pixel settings for either width or height are not considered for a match Discard Undersize Objects When this flag is set objects that are less than the minimal pixel settings for either width or height are not considered for a match String Splitting This option is very useful for attached chars 20 DLREADER PARAMETERS 2 1 1 Aspect Ratio Independence Aspect ratio independence means that objects can be taught at one size and height width ratio and be read at a different size and or height width ratio Internally the software limits the amount of change to 400 As a practical matter it should be kept to about 50 Not only does this provide greater flexibility when training but also in many applications the size of the text or objects can vary due to a variety of process causes While this feature is beneficial in many applications there are fonts or characters that can pose special problems when viewed in the light of aspect ratio independence For example what is the difference between a square period and a straight line T What is the difference between the letter O and number zero
25. rd configuration is usually fully satisfactory Each character has in fact its own rectangle distinct from others You can proceed with the Font training 0008004 1 3 2 Automatic Configuration For a ROI like that in the figure the standard configuration is not enough the characters t and z have been boxed together 2658 Wetzikon DLREADER USER S MANUAL You can try the automatic configuration by pressing the Configure button in the Auto Configuration tab of the configuration window test D Image Options OCY Options Auto Configuration Configuration Results Number of Objects 0 Horizontal Spacing 1 Inter character gap 1 VISITER v recep Charwdith Oo 999 ILLE iw Height idth Char Height uU 333 Close At this point you must try the automatic E If the result is good you can proceed with the Font training otherwise go to the Advanced configuration configuration of characters still using the button 1 3 3 Advanced Configuration The parameters that are most often changed in the advanced configuration are Horizontal Vertical Spacing Min Gap Char Constraints see window II alongside Edge Width is very useful to make the segmentation more robust If necessary also the type of segmentation used D O O Qu Character 5ize Constraints Percent amp spect Change 400 a Minimum Char width Masinum Char width 399 Minimum Char Height Maximum Character He
26. score and therefore a perfect match is 1000 The minimum score can be less than zero in some circumstances An object s score is listed on the Reader tab page Typical values range between 500 and 1000 For OCR purposes the score is not generally used For setup purposes the score is used to give the user an indication of how the DLReader is comparing the sample image to the trained font 21 c DLREADER USER S MANUAL 2 2 THRESHOLD ab Reader Threshold Fielding Training Font File Ime Type Threshold Values f Computed Low High t Linear D 100 t Non Linear Black Size 4 Options Integer Range Gairr 1 000 Outline Char Offset 0 000 Close Thresholding is nothing more than separating pixels based upon their intensity value For gray scale images the range is from O to 255 Three automatic ROI methods of thresholding are included with the DLReader computed linear and nonlinear Type Computed Computed thresholding simply calculates a single value that is used across the entire ROI to extract pixels This type of thresholding is relatively fast and works well when the lighting is uniform across the region of interest Type Linear amp Block Size Linear thresholding is used when one side is brighter than the other side and the light intensity changes uniformly from one side to the other Used in conjunction with the value specified in the edit box labelled Block Size linear thresholding calcula
27. t File Image Options DCv Opt Auto Light Dark Color Plane Light Characters Luminance Iw Gray Scale Edge width 1 Match String oo08004 Rotation Auto Rotate Angle 0 MW arn E Fail D Close naa a ee eee 7 The status of the OCR Read result window will show PASS in the case of a match p oon Ex re Y Match String 0008004 Rotation Auto Rotate Angle O Warn j Fail 0 Close OO08004 OCR Read Results img1 bmp Reader Status Output Time mm tect PASS oo0so04 1 1 mmm Summary 0008004 1 1 15 DLREADER USER S MANUAL The status of the OCR Read result window will show M C error if NOT a match in this case the ROI was moved All the characters were recognized as belonging to the trained Font but the sequence is NOT the same as indicated Match String 0008004 Rotation Auto Rotate Angle D Ware j Fail 0 aj no E RE S a e x kei iu l I u I Er I ens lt CILLUM g J a n rr SC RENT Close OCR Read Results img1 bmp Reader Status Output Time r mm test M C opsi 1 0 mmm Summary 008004 1 0 The status of the OCR Read result window will show FAIL error when NOT a match and also for characters NOT recognized in this case the ROI was moved En Match String 0008004 ESN fr Rotation Auto Rotate Angde Warn o Fait 0 Close DCR Read Results img1 bmp Reader Status Output Timefms mm test FAIL
28. tes a value on the left side of the ROI a value on the right side of the ROI and then fills in the middle values in a linear fashion from left to right The size of the steps from which to calculate the right and left side values is based on the value in the Block Size edit box Type Non Linear amp Block Size Non linear thresholding divides the ROI into the number of blocks entered in the Block Size edit box calculates a threshold value for each block and then uses that value to extract pixel data The minimum number of blocks is four 4 while the maximum number is fifty 50 As a rule this value should be set to the same number of characters or objects to read If there are spaces the width of a character or other kind of objects are present increase the block count by one for each space Non linear thresholding is designed for applications where the lighting is uneven across the region of interest Threshold Values Low amp High These values are the output of the chosen thresholding method Integer Range The Integer Range calculation changes the algorithm used to determine the threshold and to read the character This will increase the speed of the operation so that reading with a calculated threshold is almost as fast as reading with a fixed threshold Using the nteger 22 DLREADER PARAMETERS Range calculation sacrifices the accuracy when processing hard to read images The accuracy on simpler images is not affected If
29. that shows the characters making up the string DLREADER USER S MANUAL To run the training press Train Normal test Reader Threshold Fielding Training Font File Ime Train Text 0008004 Enter the string characters ar the substitution character Iw Enable Training for any unkown ar invalid objects Train Rotated Cancel Now you must test the reading by pressing the button Ell The result is shown in the window OCR Read Results OCR Read Results img1 bmp Status Output Time m Hil mm est PASS p008004 1 6 mmm Summary 0008004 1 6 Note that the space is not a character it cannot be segmented and it shouldn t be present in the trained string 10 BASIC USE OF DLREADER lt gt 1 5 UNRECOGNIZED CHARACTER SUB CHAR The character that should be displayed when a character string is NOT recognized is configurable in the configuration window The default is the character It must be a character that does NOT belong to the alphabet of the Font Reader Threshold Fielding Training Font File Imz Spacing Miscellaneous Horizontal Vertical Min Gap 2 Ho M Acceptance Bn Alternate Classifier Sub Char Dorem Ge Config Number Continue on Fail Link Char Pas E nan List Pas Score 1000 Close 1 6 FONT TRAINING TO SPEED UP OCR Not all the characters have to be entered Actually for faster recognition it s better to start b
30. the same character can be taught yielding very high read accuracies If an object is not to be trained type in the substitution character to skip that position The question mark is the default substitution character Also if only positions two and three in a triplet for example need training enter the substitution character for the first position the characters in the second and third position and then click on the OK button If fewer characters than the whole string need training then fill in the positions up to and including just those objects and no more 25 c DLREADER USER S MANUAL ab Reader Threshald Fielding Training Font File Ima z Font List Editor x Hame PO Height Delete Char Width O Next Char Rename Char Name Nest Char Purge List Golden Character se Golden Char geet se CEB eere Match Count D Clear Lists Name Use the dialog box to name the font file Description Optionally a description in the Font Description box may be entered and saved with the font list The description may be up to 255 characters in length Browse To save a font click on the Browse button to find a location to save the font file Read Loading a saved font list is similar to saving it Click on the Browse button A file browse dialog box will appear to aid in locating the correct font file Once located click on the Read button to load the font file If another fo
31. ust be replaced Select Replace Image from the File menu This will allow the user to import a new image to be used with the same reader All aspects of the reader including the ROI will remain unchanged If a series of images are to be used replacing the image will set the new image in place of the previous image If the characters in the new image appear within the ROI the user needs only click the Read Image button to read the characters 30 DLREADER PARAMETERS Sequencer prova2 bmp proval bmp Run Stop Quit Delay Time 1000 milliseconds Heset To read a series of images it is possible to use the Sequence feature Select Sequence from the OCR menu Click the Add to List button on the Sequencer box to add a string of images In the Open dialog box the images can be selected All the images must be located in the same file folder By holding the CTRL button down all the images may be selected Clicking on the Run button will start the sequencer The delay between images can be set with the Delay Time edit box The sequencer is a good feature for observing the DLReader in full operation Used with the search feature each character string can be located and read demonstrating all the features of the DLReader 31 DLREADER USER S MANUAL 3 EDGEFINDERS The first and most important part of any OCR effort is finding the characters to be read In industrial applications it is normal that the marking
32. will be done in a specific location on a surface There will no doubt be variation in the location of the marking but the marking will not be in a random location This means other things such as marking or label edges can be used to quickly find the characters of interest It is not necessary that the edge be continuous or in any specific area with respect to the characters of interest It is also possible for the characters themselves to be used by the Edge Finder to find the marking to be read A linking feature has been included so that the relative position of the found edge and the ROls of additional readers can be maintained In some cases multiple Edge Finders are set up and linked so that the first will find an edge and reposition the next to find another edge The Edge Finders can be linked in series or parallel or a combination of both to get the best positioning of the character reading ROI Rect Edge Side Left Transition Light todak Right Top Battom Link Center Edge None X D DU Y 0 00 Color Plane Gray Scale me m E Close 3 1 CREATING AN EDGE ROI File View Window Gcr Help Lu x mm E E M d GC BD ja With the last button of the OCR menu bar an Edge ROI is created The user is prompted to choose a name unique to give to the ROI The user s needs to correctly position it on the edge to be found NOTE T
33. y entering only a part of each type When you do NOT want to run the training for a character in the training string replace it with the character of sub char by the default Train Text U 8 774 Enter the string characters or the substitution character for any unkown ar invalid objects Train Rotated Cancel That way the Font is composed of one element of type 0 an element of type 8 and an element of type 4 instead of 5 elements of type 0 a type 8 and a type 4 At this point the reading must be tested by pressing the button ES The result is shown in the window OCR Read Results 11 DLREADER USER S MANUAL C uera Gi a T URL a ROMA a OCR Read Results img1 bmp Status Output Time ms mm tect Pass OOOS004 1 3 mmm urinary 0008004 0 5 In this case all the characters were recognized correctly If this had not been so it would have been necessary to proceed by running the train for unrecognized characters For example if the character O in fifth position was not recognized the new string in the train would be 0 7 OCR Read Results img1 bmp Status Output Time ms me test FAIL D008704 0 3 mmm Summary 0008004 0 5 Train Text Enter the string characters or the substitution character for any unkown ar invalid objects Ys Train Normal Train Rotated Cancel 1 7 TRAIN PATTERNS In case of group of chars that is hard to split it is p
34. y objects should be trained since the acceptance is against trained characters High resolution made may require necessarily lower acceptance values Empirical testing will yield the optimal settings with 60 being the default Sub Char When the DLReader cannot match an object with a trained object the DLReader returns the character defined in the Substitute Character Sub Char edit box found in the Reader tab page By default it is a question mark however it can be any character that is not normally read The character in this edit box is also used during training to skip over objects that are not to be trained Since training is by object position some kind of placeholder must be used when an object is to be left as is The substitute character is used for this purpose Alternate Classifier Different OCR algorithm Use Alt Score More accurate scoring used always for the Alternate classifier and enabling for the original OCR algorithm Continue on Fail If unchecked the reader returns anytime a failed read occurs This can be either too few characters as defined in the Min Char box or a misread If checked then the reader continues reading until all regions have been read Link Readers can be linked using the Link tool on the Reader tab page Linking readers is an act that only affects the ROI of each linked reader It does not affect the independence of the readers It also does not affect any readers that are not linked to that
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