TODO

TODO Items
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version 1.0.0: (planned TBD)
FOCUS: remaining gaps, testing, documentation
  o libdmtx:   Investigate using MMX to optimize inner loops
  o libdmtx:   Investigate using threads to split up image processing
  o testsuite: Generate metrics in reproducible format to enable historical tracking
  o testsuite: Investigate option of embedding decoded text into PNG test image comments
  o testsuite: Tests should compare scanned results to embedded PNG comments
  o testsuite: 'make test' writes metrics file
  o testsuite: 'make test' confirms performance

version 0.9.0: (planned TBD)
FOCUS: refactor encoding engine, FNC1, macros
  o libdmtx:   Implement --auto-fast option using algorithm from spec (lighter & faster?)
  o libdmtx:   Structured append reading and writing
  o libdmtx:   Use new Edifact decode function that doesn't assume full triplet
  o libdmtx:   Check ProcessEndOfSymbolTriplet() for same problem fixed in Edifact
  o libdmtx:   Rewrite encoder(s) to not need "twothirdsbits" tracking (fixes multiple bugs)
  o libdmtx:   autobest: Consider tracking 3 separate channels for triplets, 4 for quads
               in order to account for all possibilities. (In case it's not always best
               to latch into scheme as soon as possible)
  o dmtxread:  Print character values (not just codewords) from --codewords (-c) option
  o dmtxread:  Print out image representing "unstretched" barcode
  o dmtxread:  Print color weights based on direction
  o dmtxread:  Diagnostic image shows tighter-fitting outline
  o dmtxread:  Change dmtxread to print out dump of both failed and successful barcodes if requested
  o dmtxread:  Change dmtxread to print out mis-read modules somehow ... additive, subtractive?
               - Build color vector that describes jump from background to foreground color
               - When module is determined to be "off" then add half of color vector
               - When module is determined to be "on" then subtract half of color vector
               - resulting image should clearly show misread modules
  o dmtxwrite: Use MagickCommentImage() to tag images with messages
  o dmtxwrite: Print character values (not just codewords) from --format=c (-fc) option
  o dmtxwrite: Verbose messages describing encoding process
  o testsuite: Implement exhaustive comparison between --auto-fast and --auto-best

version 0.8.0: (planned TBD)
FOCUS: region detection refinement, multiple barcode scanning, structured append
  o libdmtx:   Replace DmtxDirection (e.g., DmtxDirUp) with index range 0-7 (?)
  o libdmtx:   Finish fec integration (encode_rs_char, aLog[], etc...)
  o libdmtx:   Fast Hough fit followed by precision handle fit
  o libdmtx:   Optimizations need to perform multi-barcode scans
  o libdmtx:   Rename outputIdx to outputLength? (Count pad codewords instead of pointer)
  o libdmtx:   Use 100x faster pixel access in PointFlow calculation pass
  o libdmtx:   Use calibration edge alignment to set precise locs for all edges
  o libdmtx:   Rename math types to drop unnecessary numeral (DmtxVector2, DmtxRay2, etc...)
  o libdmtx:   Implement consistent and robust error handling (errno.h + custom)
  o libdmtx:   Implement structured append symbols
  o libdmtx:   Image quality metric
  o libdmtx:   Inspect SDL image packing conventions (stride vs. pad, etc...)
  o libdmtx:   Clean up API for use with external ROI finders
  o libdmtx:   Is there a good way to know if dmtxRegionFindNext() timed out or finished file?
  o libdmtx:   Files should compile individually (include dmtx.h and dmtxstatic.h)
  o libdmtx:   library should never call exit()
  x libdmtx:   Fixed ECC bug for 144x144 case (thanks Huver!)
  o dmtxread:  Flatten deeply nested loops in main()
  o dmtxread:  Add true scan timings that factor in linking, startup, image load
  o dmtxwrite: Add support for setting foreground and background colors
  o dmtxwrite: Consider adding "--strict" for single scheme requests (or make strict default?)
  x dmtxwrite: Fixed: Not waiting for EOF on standard input (Bug 2988977)
  o dmtxquery: Write XML for dmtxquery consumption
  o dmtxquery: Initial working version (parses XML)
  o wrapper:   Fix php-dmtx license (re-confirm with Christian) (or remove wrapper)
  o project:   Consider --disable-magick, while providing native PNM support to utils
  o project:   Clean up source file permissions (write script to detect outliers?)
  o project:   Any way to ask Magick to filter out GS (and other) warnings?
  o project:   Conditional use of local getopt.c
  o project:   Devise approach for recurring tasks (enabling $Id$, checking SVN commits)

version 0.7.2: (04-Sep-2009)
  x libdmtx:   Added initial macro decoding support (thanks Marlon!)
  x libdmtx:   Fast quad fill for dmtxDecodeMatrixRegion() (thanks Mackenzie!)
  x libdmtx:   Fixed capacity bug with rectangle requests
  x wrapper:   New Vala wrapper (thanks Evan!)
  x wrapper:   Wrapper integration in build system (thanks Evan!)
  x project:   Add libdmtx-X.X.X.zip as source package option
  x project:   Add libdmtx-win32-X.X.X.zip as binary package option
  x project:   Add "project" directory to EXTRA_DIST in Makefile.am

version 0.7.0: (02-Mar-2009)
  x libdmtx:   Fix 64b->32b int assignment warnings
  x libdmtx:   FNC1 and correct upper shift (thanks Robin!)
  x libdmtx:   Support byte-padded row sizes via dmtxImageSetProp()
  x libdmtx:   Move image scaling factors to DmtxDecode
  x libdmtx:   Add DmtxUndefined to replace "-1" for undefined fixes, offset, etc...
  x libdmtx:   Update dmtxImageCreate() parameter options
  x libdmtx:   Switch DmtxFlipNone represent top-down row order
  x libdmtx:   Add dmtxEncodeSetProp() and dmtxEncodeGetProp()
  x libdmtx:   Relocate scan cache from DmtxImage to DmtxDecode
  x libdmtx:   Remove status from DmtxPixelLoc
  x libdmtx:   Configurable pixel packing
  x libdmtx:   Removed DmtxRgb, dmtxcolor.c, DmtxColor3, and DmtxGradient
  x libdmtx:   DmtxTrue/DmtxFalse replaces DMTX_TRUE/DMTX_FALSE
  x libdmtx:   DmtxPass/DmtxFail replaces DMTX_SUCCESS/DMTX_FAILURE
  x libdmtx:   Change all major types to use Create() and Destroy() convention
  x dmtxread:  Option to print extended ASCII as UTF-8 (thanks Robin!)
  x dmtxread:  Fix diagnostic image output
  x dmtxread:  Fix misrepresented capacity in verbose mode
  x dmtxwrite: True vector SVG output bypassing ImageMagick (thanks Richard!)
  x dmtxwrite: Use Magick to write images of major image formats
  x dmtxwrite: Bad option should give short "invalid option -- N; --help for more"
  x dmtxwrite: Use HandleArgs() to capture requests, and process afterward
  x dmtxwrite: Switch to using new dmtxEncodeSetProp() approach
  x wrapper:   New Java wrapper (thanks Pete and Dikran!)
  x wrapper:   New .NET wrapper (thanks Vali and Joe!)
  x project:   Update documentation to reflect API changes
  x project:   Add comment to wiki pages that points to source README
  x project:   Figure out earliest usable Magick version for configure.ac
  x project:   Add simple_test project to libdmtx.sln
  x project:   Rename wiki page to "Windows (VisualC)"
  x project:   Introduce "project" directory for non-autotools platforms
  x project:   Rename "wrappers" directory to "wrapper" for consistency
  x project:   Create a common tasks and release checklist document

version 0.6.0: (23-Nov-2008)
  x libdmtx:   Initial work preparing for custom pixel packing in future
  x libdmtx:   Begin static analysis cleanup with splint
  x libdmtx:   New --disable-dmtxread and --disable-dmtxwrite [Romain]
  x libdmtx:   Ability to specify max/min expected barcode sizes
  x libdmtx:   New edge neighbor tracking (Hough Transform + 2 way edge cache)
  x libdmtx:   Info cache to track scan progress and avoid rescanning pixels
  x libdmtx:   Scan multiple barcodes within an image
  x libdmtx:   Significantly reduced memory footprint
  x libdmtx:   Major reduction in floating point operations
  x dmtxread:  New informative return codes (found, not found, error)
  x dmtxread:  Read input from STDIN
  x dmtxread:  GraphicsMagick support for image reading [Olivier]
  x dmtxread:  JPEG reading support [Ryan]
  x dmtxread:  Diagnostic images display trail left by scanning logic
  x dmtxwrite: Option to write output to STDOUT [Olivier]
  x wrapper:   PHP wrapper now compiles with recent libdmtx
  x wrapper:   New encoding/decoding Ruby wrapper [Romain]
  x project:   Dedicated README.xxx instructions for specific platforms
  x project:   Various improvements for cross platform builds

version 0.5.2: (04-Sep-2008)
  x libdmtx:   Move SetRangeLimit and SetScanRegion into library
  x libdmtx:   Replace DMTXUTIL_SUCCESS/ERROR with DMTX_SUCCESS/FAILURE
  x libdmtx:   Add edge threshold filtering
  x libdmtx:   Add encoding support for 144x144 barcodes
  x libdmtx:   Fixed encoding case when message starts with two digits
  x libdmtx:   Fixed bug in range limit option
  x libdmtx:   Add dynamic image shrinking (pixel skipping)
  x libdmtx:   Add step-by-step diagnostic image dump (debug build)
  x libdmtx:   Fixed bug in minimum scan gap setting
  x libdmtx:   Removed y-flip from internal pixel storage
  x libdmtx:   Added strict border tests to eliminate false positives
  x libdmtx:   Added squareness deviation filter
  x libdmtx:   Implement simplified Hough transform for locating first edge
  x libdmtx:   Several behind-the-scenes performance enhancements
  x wrapper:   Python wrapper update; 15x faster (thanks Jonathan!)
  x wrapper:   New PHP wrapper code added
  x project:   Various improvements when building for OS X and FreeBSD

version 0.5.1: (01-Jul-2008)
  x libdmtx:   Fixed Extended ASCII encoding bug
  x libdmtx:   Fixed error correction bug related to multiple interleaved blocks
  x libdmtx:   Added timeout condition for region detection
  x libdmtx:   Allow partial and complete disabling of error correction
  x libdmtx:   Replaced DmtxPixel struct with DmtxRgb for safe pixel copies
  x libdmtx:   Tighter integration with libfec
  x dmtxread:  Conditional build logic for libtiff
  x dmtxquery: Start new utility to extra information from dmtxread output
  x testsuite: Started unit test executable for low level testing
  x wrapper:   New Cocoa wrapper for iPhone, iPod Touch, OS X (thanks Stefan!)
  x project:   Include local copies of getopt1.c getopt.c getopt.h
  x project:   Various things to help compiling in MS VC++
  x project:   Added missing header comments

version 0.5: (13-Apr-2008)
  x libdmtx:   Rework encoding and decoding API for consistency and intuitiveness
  x libdmtx:   Handle region detection and region decoding as separate tasks
  x libdmtx:   Pass found regions back to calling app before attempting decode
  x libdmtx:   Image mask approach (for performance and multi-barcode scans)
  x libdmtx:   Remove "2" from functions named *MatrixRegion2*() (whoops)
  x libdmtx:   Fix TestForEndOfSymbolEdifact() to handle special cases correctly
  x libdmtx:   Roll scan pattern into core library (inward breadth-first cross)
  x libdmtx:   Replace dmtxScanLine() with dmtxScanPixel()
  x libdmtx:   Implement 4-direction weighted module decisions (eliminates thresholds)
  x libdmtx:   Error correction using libfec (thanks Florian!)
  x dmtxread:  Add ability to scan portion of image
  x dmtxread:  Add --diagnose option that dumps image with embedded scan infomation
  x dmtxread:  Added Z rotation angle (in degrees) to verbose output
  x dmtxwrite: Move ASCII and codeword output to separate --preview option
  x dmtxwrite: Added -R option for setting image print resolution in dpi (PNG only)
  x project:   Remove gltest and simpletest from default build target
  x project:   Update Subversion to be keyword friendly ($Id$)
  x project:   Updated documentation to reflect API and option changes
  x testsuite: Moved all public images to common directory with single copyright file

version 0.4: (07-Dec-2008)
  x libdmtx:   Remove arbitrary sz scaling (100.0) since it doesn't matter anyway
  x libdmtx:   Fix 4 bottom-right modules in sizes where they are not used (thanks Matthias R.!)
  x libdmtx:   Replace callback references with preprocessor macros
  x libdmtx:   Implement remaining encodation schemes for encoding (X12, Base 256, etc...)
  x libdmtx:   Implement remaining encodation schemes for decoding (X12, Base 256, etc...)
  x libdmtx:   Implement --auto-best option for best possible encoding efficiency
  x libdmtx:   Implement multi-region symbols
  x libdmtx:   Read and write rectangle shaped barcodes
  x libdmtx:   Use GNU autotools (autoconf, automake, libtool)
  x libdmtx:   New region detection overhaul
  x libdmtx:   Fix chcon error in Makefile (right answer might be to use autoconf)
  x bindings:  Include initial version of Python bindings from pydmtx project (thanks Dan!)
  x bindings:  Add decoding functionality through Python
  x bindings:  Expose new encoding functionality through Python
  x dmtxread:  Fix dmtxread crash when same barcode is found more than 16 times
  x dmtxread:  Verbose messages describing traits of detected barcodes
  x dmtxread:  --codewords option to print codewords instead of decoded message
  x dmtxread:  --newline option to insert newline character at end of output
  x dmtxwrite: Additional output formats (PNG, ASCII, codewords)
  x testsuite: 'make test' executes regression tests for encodation
  x testsuite: Add marathon images to project (thanks John!)

version 0.3: (15-Oct-2006)
  x Use preprocessor to pull code into one big file before compiling
  x Update Makefile to handle monolithic approach; add targets for test, util, tarball
  x Rename DmtxInfo struct and variables to DmtxDecode (for consistency with DmtxEncode)
  x Merge placement logic into single implementation for both encoding and decoding
  x Deploy codebase to SourceForge CVS
  x Add revision control keywords to source files
  x Implement remaining encodation schemes in dmtxdecode.c (X12, Base 256, etc...)
  x Create separate file for callback functions (allows them to be optional)
  x Move PNG (and other format) logic and dependencies to dmtxread, dmtxwrite, etc...
  x Fix the regressions (crash bugs) introduced during v0.2 structural rework
  x Add multi-page TIFF capabilities to dmtxread
  x Move pure decode calls from dmtxScanLine into a dmtxdecode.c function
  x Sample module color from more than one pixel location
  x Rename DmtxVector3 to DmtxColor3 and merge into dmtxcolor.c
  x Fix LoadPngImage() in dmtxread.c to return image count
  x Add package/build dependencies to INSTALL file
  x Build coding style test scripts
  x Replace current calibration size estimate with new approach
  x Size step size dynamically according to pixel size
  x Improved dmtxwrite (fixed bugs, implemented -o option)
  x Increase dmtxread default scanline count (feasible because of better stability)
  x Add man page for dmtxwrite

version 0.2: (11-Jun-2006)
  x Move dmtxCapturePixel routine to library code
  x Initial restructuring of code for architectural goodness
  x Improve API for real-world use (and not just dumping results to STDOUT)
  x Add "dmtxread" command line utility
  x Add "dmtxwrite" command line utility
  x Implement error detection
  x Create "simpletest.c" for full-circle processing
  x Use libpng(3) in library to read Data Matrix images
  x Slap together some basic documentation

version 0.1: (22-Apr-2006)
  x Cycle texture images with right-click
  x Complete PlotPoint so it handles floating rows and columns
  x Implement right and left directions of FollowEdge
  x Call right and left edge following scans started from vertical step scans
  x Implement 2D vector and matrix functions
  x Trace lines with actual line object (2D ray)
  x Turn corners when encountering the end of a followed line
  x Build 2d transformation to wrap around region, assuming parallelogram
  x Display pane 4 with reverse-transformed image capture
  x Enhance dmtxCapturePixel to use "area averaging" instead of nearest neighbor
  x Figure out why squares are 3 pixels off (to start: draw white gl lines over follower paths)
  x Add callback function for PlotEventPoint(x, y, event_type)
  x Improve follower logic (weighted line fit)
  x dmtxGetPixel: do averaged interpolation followed by a tMin/tMid/tMax cutoff
  x Add in de-skew transformation
  x Refactor vector libraries to consistently list target parameter first
  x Calibrate based on calibration lines
  x Shrink-fit transformation around region


Future Versions:
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  o libdmtx:   Capture high-level design in documentation (data flow, module analogies)
  o libdmtx:   Try bi-linear approximation (instead of linear) in follower edge detection
  o libdmtx:   Implement fixed point math functions for use on mobile platforms
  o libdmtx:   Add calibration functionality to remove spherical distortion


Perhaps Never:
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  o libdmtx:   Implement pre-ECC200 Data Matrix standards (big effort/low demand)


Website:
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  o Explore using single background image instead of split
  o Add what we currently do, don't do, would like to do in the future
  o Add http://hosted-projects.com/trac/hudora/public/wiki/huBarcode to resources page


Proposed Change: Modularity
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Make finder bar detection pluggable so a separate future version
can be made for dot peen pattern detection (remaining steps would
be unchanged).


Proposed Change: Region Calibration
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The current calibration technique relies solely on points and
angles found during the Hough process, and uses the calibration
bar only to detect symbol size. A more robust approach might take
advantage of the calibration bars' repeating pattern to extract
precise edge locations for the adjacent edges. Doing so will
provide extremely accurate symbol regions since each of the 4
edges will contain a precise anchor point instead of relying on a
potentially fuzzy edge measurement. This will also help with
barcodes created using undersized/oversized printing process.


Boundary Hough test
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Increment line
Decrement interior line


Vanishing Point detection (high-res Hough)
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Known:
  "L" alignment edge location

Approach:
  1) Sample each pixel in a parallelogram formed by the "L" edges
     and implied opposing parallel edges
  2) Sample each pixel within region exactly once
  3) Perform Boundary Hough test twice, once for each edge of "L"
     to define interior direction
  4) Detect interior edges as pattern of points in Hough grid
  5) 2 skew tranforms should be sufficient to correct any
     perspective distortion
  6) Find calibration edges and extract exact edge locations

Note: Initial implementation may use regular Hough if much simpler


Bahamas Approach
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1) Calculate point flows, store in cache (maybe?)

2) Calculate local low-res Hough, store in overlapping N^2xN^2
   grid (probably 16x16 or 32x32). Store 4 values, (H+ H- V+ V-),
   which can be compared later to detect alternating module
   patterns. Values are determined by compass direction.

   This step should respect pixel skipping (i.e., shrinking)
   option. Also consider adding ability to grow instead of
   shrink, causing single pixel modules to appear larger.

3) For each local region, find vanishing point and module size
   (high-res Hough with known limits). Attempt decode if barcode
   presence is detected. If both vanishing point and module size
   are known, can be confident about scan results (either success
   or failure).

4) Increment to next larger region size by combining small local
   regions and repeat #3. Continue until all sizes are considered