README: update to reflect the new build and installation processes.

[Ale.git] / ChangeLog

==========
Change Log
==========

This file includes detailed change information for each release; for summary
information, see the 'NEWS' file.


0.8.5 Prerelease

o       Add file 'TODO', containing a to-do list for future releases.

o       Add AUTHORS file, in accordance with the autotools packaging
        standards.

o       Revise Changelog name to autotools-approved ChangeLog

o       Add NEWS file containing mailing list and Freshmeat announcement text
        for versions 0.5.1 through 0.8.4.  This file is required by autotools.

o       Add options --f{ex,crop} for frame-coordinate exclusion regions.

o       Add autotools-based configuration, build, and installation facilities,
        replacing the earlier Makefile-based configuration and build process.

o       Modify command-line interface to accept certain scope operators, and
        to increase uniformity of syntax.

o       Move input interface details, including option handling, messages,
        and help information, to the ui/ subdirectory.

o       In d3::scene, always use filler spaces when --pc all is specified.

0.8.4 2006-May-14

o       Fix build error noted by Gregory Maxwell and re-tag version.

o       Add fine-grain UI updates for 3D operations when using ui=tty.  Reduce
        tty UI status update frequency to at most once per second.

o       Modify --3dpx to affect scene geometry rather than rendered
        pixels.  In certain cases, this change should allow removal of objects
        close to the camera, hence revealing objects further away.

o       Add to the Makefile a HASH_MAP option that can be used to assign the
        3D spatial info structure a hash map type instead of the standard STL
        map type.  As this is likely to break things, it is currently
        undocumented.  HASH_MAP=GNU seems to compile with g++ 4.0.x but
        has not otherwise been tested.

o       Add support for synthetic focus via the --focus option, including
        focus with horizontal and vertical tilt.  Adding simulated focus
        effects, including tilted and swung focal planes, was suggested by
        Gregory Maxwell.

o       Add support for filtering 3D output with --3d-filter.  This
        is now the default behavior.  Add an option --3d-chain for selecting
        the filter chain used for 3D output.  (See --hl and --hq for details.)

o       Fix dimension comparison bug in d3::space::traverse::get_next_split().

o       Implement an experimental approach to 3D subspace candidate selection;
        this seems to perform poorly in most cases due to parallax effects.
        See the source code for details.  (Option --subspace-traverse)

o       Add adaptive weight decomposition to 3D occupancy algorithms.

o       Move low-level code concerning scale and level-of-detail from
        d3::scene to d3::pt.

o       Move code concerning the nature of space from d3::scene to 
        d3::space.

o       Interpolate to generate smooth 3D depth output.

o       Remove older 3D rendering code. 

o       Add decimation options --di-upper, --di-lower, and --do-try for
        reducing the complexity of 3D scene geometry, hence reducing the
        number of operations required for occupancy updating.

o       Add a script 'transform' for applying an inverse projective
        transformation.  Recalculation of transformations was suggested by Rob
        Stewart (ALE mailing list message, 2005-Dec-28).

o       Add dates to the Changelog, using dates in comments in the download
        page on the website for versions prior to 0.8.0, and using dates from
        the darcs repository for versions 0.8.0 and later.


0.8.3 2005-Dec-23

o       Add option --3dpx to specify 3D regions to exclude during final
        rendering, using a single depth for each pixel in each frame of
        rendered output.  (Evaluates at the depth used in depth-rendering.)

o       Add option --pc to specify which pairwise comparisons should be
        performed.

o       Add --et option to specify encounter thresholds.

o       Clean up d3::scene to remove triangle-mesh code.

o       Add an option --def-nn to allow definition of pixels in output images
        to take values from neighboring pixels within a certain radius, in
        cases where they would not otherwise be defined.

o       Modify representation of 3D subspaces so that refined subspaces
        are roughly cubical, and to allow refinements at multiple
        resolutions.

o       Fix bugs in 3D color and occupancy updating caused by bounding
        box miscalculation.

o       Add option --pa to set the number of point candidates accepted
        for each pair of cameras (pairwise ambiguity).  The default
        of 3 preserves existing default behavior.

o       Add option --oui for determining occupancy update iterations.
        The new default is 10, halving the previous default of 20.

o       Add option --tcem for scoring point candidates by third-camera
        views.  The default of 0 preserves existing default behavior.


0.8.2 2005-Nov-22

o       Add magical file 'dump:' for listing color values numerically
        to stderr.

o       Transition from a subdivisible triangle model to a subdivisible 
        space model, using a rudimentary implementation of Hans Moravec's 
        notion of occupancy.

o       Add support for view and depth output from arbitrary cameras.

o       Add clipping plane options for 3D modeling.

o       Fix various bugs in control-point alignment reported by Gregory
        Maxwell.


0.8.1 2005-May-6

o       Modify --q1 to use median-value incremental rendering.

o       Add support for median-value incremental and Irani-Peleg rendering.
        Using a statistic other than the mean was suggested by Scott Scriven
        as a means of eliminating non-uniform artifacts.  Using the median
        seems to improve performance on Scott Scriven's example sequences, as
        well as on the scaled output of fine:sinc*lanc for sparse inputs.

o       Move ale-psf-calibrate to a new scripts directory.

o       Add support for using control points in 2D and 3D alignment, as well
        as in 3D model construction.  New options include '--gs points',
        '--cpf-load=', '--cpp-upper=', '--cpp-lower=', '--va-upper=', and
        '--st'.

o       Fix enumerator compile bugs noted by Gregory Maxwell and Tom Holroyd
        to cause compilation failure under GCC 3.4.

o       Add average magnitude comments to transformation data file output.

o       Add a color adjustment option --exp-mult=.

o       For 3D scene reconstruction, use a new unified surface model in place
        of the depth-based multi-model approach used in 0.8.0.  The new model
        is adjusted on the basis of edge, angle, and color measures.


0.8.0 2005-Jan-12

o       Add a flag --exp-meta-only which causes tonal registration to be
        performed only on the basis of exposure metadata (e.g., data encoded
        as EPPM extended attributes).  This approach was suggested by Gregory
        Maxwell.

o       Set image offsets in d2/render/combine.h.  This allows Irani-Peleg
        rendering to work with --crop when the default rendering chain
        includes more than one rendering invariant.

o       Perform Irani-Peleg updating separately by channel instead of
        using vector operations.  This allows divide-by-zero and other
        conditions to be localized to particular channels.

o       Modify the Irani-Peleg renderer to use estimate-based certainty.  This
        seems to improve noise characteristics significantly.

o       Write the results of tonal registration as a comment in the 
        transformation data file.

o       Add support for PPM with extended attributes (EPPM).  Attributes
        handled specially include black level, shutter speed, aperture, and
        ISO (or gain).

o       Add experimental cost calculation routines to d3/scene.h.

o       Modify euclidean alignment so that perturb-upper and perturb-lower
        apply to rotational arclength.

o       Fix an index variable bug in d2::image_bayer_ale_real::trigger().

o       Modify d2::exposure one-sided certainty so that the 'one-sided'
        condition only applies to bright (>50%) areas.  Applying it to dark
        areas has no clear benefit, and an experiment by Gregory Maxwell
        demonstrates that doing so can exacerbate noise.

o       Modify d2::align to use unscaled input images when the scale factor
        is larger than 1.0, or when a scaled_filter interpolant is being used.

o       Modify d2::image::scale() to allow scale factors in the interval 
        (0, 1), and modify the command-line interface and help text to reflect
        this change.  --scale= now accepts all finite positive values.

o       Add user interface options --ui=stream and --ui=tty.  The latter
        includes more detailed status output when terminal width information
        can be obtained (esp. when IOCTL=1 is set at compile time), and is the
        new default.

o       Move certain user interface elements to the source subdirectory ui/.

o       Modify d2::render::ipc::_ip_frame_correct() so that exposure
        re-estimation uses a ratio of weighted sums instead of a weighted
        average of ratios.

o       Modify d2::align::set_exposure_ratio() so that alignment 
        weights and certainty values are taken into consideration.  

o       Add a --cw option to weight alignment error by certainty values,
        as suggested by Gregory Maxwell.  This allows the contributions of
        pixels at maxval to be diminished, which can increase alignment
        success in certain cases.

o       Replace functions d2::incremental::{increase,decrease}_extents()
        with new functions that take exclusion regions into account.  The new
        functions should also fix a boundary-calculation bug reported by
        Gregory Maxwell.

o       Modify d2/render/ipc.h to handle exclusion regions more effectively.

o       Add --crop argument, which excludes the spatial complement of a
        specified area over a specified set of frames.  Gregory Maxwell notes
        several advantages of internal over external crops, including
        preserving knowledge of position in the uncropped frame, which among
        other benefits allows natural handling of Bayer patterns.

o       Modify rx_parameters in d2/render.h to use the ale_pos data type
        instead of int.  This should allow exclusion regions to be calculated
        more accurately.


0.7.3 2004-Dec-1

o       Add incremental 3D reconstruction output.

o       Remove the reference to a non-existent web page in
        unsupported::fornow().

o       Allow device-specific bayer patterns to be overridden by the --bayer
        option.

o       Add an option for explicitly setting the camera view angle.  Make the 
        default view angle 43.7 degrees.

o       Implement optimizations that reduce the memory footprint when 3D
        options are used.

o       Modify the 3D cost reduction algorithm.  The new algorithm seems to
        offer better results than the old in cases tested thus far, and does
        not require that spatial extension be enabled.

o       Add support for the Canon 300D with a 50mm f/1.4 lens (specifying view
        angle), as well as experimental support for the 50mm f/1.4 lens at 1.4
        (specifying a linear PSF).  Also add support for 50mm f/1.8 and 85mm
        f/1.8 lenses, specifying view angles as specified in the chart at
        http://www.acapixus.dk/photography/angle_of_view.htm

o       Don't output final data when --psf-match is specified.  Doing so
        would be useless anyway, and apparently causes a segfault.

o       For cases where --psf-match is specified, modify the exposure settings
        for the final input image (i.e., reference image) so that default
        exposure is used, and modify the bayer pattern settings so that no
        bayer pattern is used.  (The first of these modifications requires
        changes in the way that the array of input exposures is stored.)

o       Optionally (when OPTIMIZATIONS == 1) use the output of the default
        rendering chain directly as the Irani-Peleg initial approximation,
        instead of copying it.

o       Add support for PSF convolution and scalar multiplication.

o       Move all PSF parsing logic to a new file: d2/render/psf/psf_parse.h

o       Modify help argument processing so that several help arguments can be
        specified at a time.  Change the usage text to reflect this.

o       Fix concatenated help output; outputs from all help options are now
        represented.  (3D help had been omitted in 0.7.2.)

o       Add a check to ensure that at most one --q* option is specified.
        The issue of multiple --q* options being specified was raised on the
        ALE mailing list by Viktors Rotanovs.  As there is currently no
        support for this, generating an error message is appropriate.


0.7.2 2004-Oct-26

o       Add cost-minimizing code to reconstruct 3D scenes from 2D inputs.
        (This code is currently very experimental.)

o       Add rudimentary device support for raw, linear files from the Canon
        EOS 300D (Digital Rebel) SLR.  CRW files may not be directly usable
        under all configurations; in cases where they are not, Dave Coffin's
        dcraw program, with arguments -d -4, will produce a raw, linear PPM
        file.  See http://www.cybercom.net/~dcoffin/dcraw/

o       Add a new option --gs-mo to establish a minimum overlap area for
        global searches.  This may allow more of Derrick Brashear's historical
        USGS contour map image sets to align successfully.  (from
        0.7.1-patch2)

o       Allow the scale factor to be explicitly set to one. (from
        0.7.1-patch2)

o       Print version information to stdout instead of stderr. (from
        0.7.1-patch2)

o       Add a rudimentary test suite. (from 0.7.1-patch2)

o       Add support for --perturb-{upper,lower}=x%, where the value x% is
        specified as a percentage of the smallest image dimension.  Use of
        percentages to specify bounds was suggested by Jeff Epler. (from 
        0.7.1-patch1)

o       In render::is_excluded(), add the offset before checking exclusion
        regions. (from 0.7.1-patch1)

o       Add code to shrink the accumulated image in d2/render/incremental.h,
        so that superfluously large undefined areas are never present.  This
        may improve operation of '--gs inner' in some cases. (from
        0.7.1-patch1)

o       In d2::align::_align(), rescale default_initial_alignment in parallel
        with the current transformation, so that it can be used again, if
        necessary. (from 0.7.1-patch1)

o       Add experimental options --perturb-source and --perturb-output, which
        allow some refinement of the manner in which perturbation occurs.
        (from 0.7.1-patch1)


0.7.1 2004-Aug-27

o       Fix --visp segfault when not using last: filters.

o       Add help mode --hA to display all help pages.

o       Add circular point-spread function option "circle=<diameter>".

o       Add support for the ov7620 sensor (raw, linear modes only).  (Updated
        from 0.7.0-patch1 to specify a linear PSF.)

o       Add global search option --gs to fix an alignment problem reported by
        Bert Douglas.  (Also included in 0.7.0-patch1.)

o       Change transformation::eu_{get,set,modify}() so that externally
        visible values are interpreted in the context of transformations
        between scaled images, while internal values represent transformations
        between unscaled images.  (Bugfix for 0.7.0.  Also included in
        0.7.0-patch1.)

o       d2/tfile.h: Ensure that eu[] parameters are properly scaled when read
        and written.  (Bugfix for 0.7.0. Also included in 0.7.0-patch1.)

o       Fix order-of-operations bug in d2::image::scale_by_half().  (Bugfix
        for 0.7.0 and earlier versions.  Also included in 0.7.0-patch1.)

o       Scale alignment weights for reduced level-of-detail in d2::align().
        (Also included in 0.7.0-patch1.)

o       For reduced level-of-detail alignment reference images, filter
        using alignment weights.  (Also included in 0.7.0-patch1.)

o       Add speed optimizations for filtering in the Euclidean case, but
        leave these disabled, since they are not safe.  (Also included
        in 0.7.0-patch1.)


0.7.0 2004-Aug-06

o       Add support for algorithmic alignment weights.  This requires 
        POSIX fork() and execlp(), so add a Makefile variable for POSIX.

o       Add support for frequency-based alignment weights.  Angelo Pesce
        had initially suggested the related (or more general) idea of
        edge-based alignment.  Frequencies were chosen because of their
        conceptual simplicity.  This option requires that FFTW be linked.

o       Add support for specifying per-pixel and per-channel alignment weights
        by providing an additional weight-map image, as suggested by Bert
        Douglas.

o       Remove support for USM.

o       Add multiple default settings: q0, q1, q2, qn, qr.

o       Partition help into sections, and add a section for transformation
        data file help.

o       Add a device type for the XVP610 camera in 640x480 mode.

o       Modify the divisor in d2/render/ipc.h to ensure convergence when
        using multiple varieties.

o       Add experimental handling for Bayer patterns.

o       Add experimental video stabilization options.

o       Add options to control output range.  By default, use the range of the
        original frame.

o       For incremental rendering, add general filtering options.  Drizzling
        options are no longer supported as such, but the help output offers
        examples of how to emulate old drizzling/merging techniques (roughly).

o       Add options --fail-default and --fail-optimal to select the desired
        failure mode.  --fail-default uses the default alignment in the case
        of failure.
        
o       Add option --ex, to support exclusion volumes.  Region exclusion was
        first suggested to the author by Dewayne VanHoozer as a means of
        solving the 'closed eye problem' in group photography.

o       Add a barrel distortion adjustment multiplier and rate options.

o       In d2/transformation.h, add parameters for barrel distortion correction.
        In d2/tfile.h, add new barrel distortion command 'B'.  The approach
        taken is based on that of Helmut Dersch's PanoTools.  (i.e., a
        polynomial in radial distance is used.)

o       Increment the latest supported transformation file syntax to version
        3.  This version supports transformation of the original frame, as
        well as other new features described above.

o       Move d2/gpt.h to d2/transformation.h.

o       In d2::align, add support for original frame transformations.

o       In d2::align::diff() and d2::align::set_exposure_ratio(), treat cases
        with and without extension identically.

o       Report unrecognized transformation file commands as errors instead of
        warnings.

o       In the transformation data file handler, report incompatible
        transformation types as an error instead of as a warning.


0.6.0 2004-Feb-10

o       Add a generalized, but rudimentary, implementation of Steve Mann's
        notion of 'certainty'.  For more details, see
        http://wearcam.org/comparametrics.pdf

o       Make stdin filter height and width independent of each other.

o       In the Irani-Peleg renderer, skip frames that fail to reach the match
        threshold.

o       Convert some operations on pixels and points into vector syntax 
        through C++ operator overloading.

o       Add command-line options to select plain or raw PNM/PPM formats.  Remove
        makefile variable PLAIN.

o       Add command-line options to select 8/16 bits per channel.  Remove
        makefile variable BITS.

o       Revise the device configuration xvp610_320x240 to use a new
        filter, reflecting driver updates (see the relevant web page
        http://auricle.dyndns.org/xvp610/ ) and support for non-linear
        colorspace point-spread functions.

o       In the Irani-Peleg renderer, use a discrete Fourier transform to
        ensure that each (point-spread function, backprojection kernel) pair
        satisfies condition (9) from theorem 4.1 in the source paper.

o       Add a point-spread function rasterizer.  

o       Extend the --replace option to support drizzling.

o       Add support for exposure registration (i.e., matching of exposure
        between different frames).

o       Change -Os to -O2 in the Makefile, since -Os no longer achieves speedup
        in the most critical codepaths.

o       Add command-line support for summation of point-spread functions.

o       Add a polymorphic point-spread function type psf and convert all
        external interfaces of ipc.h and usm.h (formerly hf-enhance.h) to use
        this type.  

o       Fix memory leak in d2/render/combine.h:get_image().  (This fix is also
        included in a patch for 0.5.1.)

o       Modify the USM renderer to write output when incremental output is
        enabled.

o       In the USM renderer, now only defined pixel values contribute to the
        mask.  Also, undefined values are no longer masked.

o       Update e-mail address information.

o       Modify the Irani-Peleg calibration script into a general point-spread
        function calibration script, using a new built-in point-spread function
        evaluation module to rate candidates.

o       Irani-Peleg and USM (High-frequency enhancement) renderers now
        use the same point-spread function configurations.  New options --ips,
        --usm, --lpsf, --nlpsf, and --device subsume and extend the
        functionality provided by options --ip, --ipc, and --hf-enhance.

o       Add support for convolutions in non-linear colorspace.  This feature
        is enabled and configured by the command-line option --nlpsf.  (See
        also the item above.)

o       Linearize channel values within internal data structures so that most 
        ALE operations are performed on linear data.  Steve Mann discusses the
        use of linear representations in image processing, e.g. in his paper
        http://wearcam.org/comparametrics.pdf .  We assume a simple power-law
        response by default.

o       Modify the image class to use a floating-point data type for 
        storing pixels.

o       Modify the README to remove information covered in the User Manual.

o       Revise identifiers and comments in d2/render/ipc.h to better reflect
        the terminology used in the source paper by Irani and Peleg.

o       Consoldiate code for computing the position and dimensions of a pixel in a
        new coordinate system, and use this new abstraction to reduce the code
        size of d2/render/ipc.h and d2/render/drizzle.h (Irani-Peleg and
        drizzling code, respectively).

o       Change several instances of 'double', 'float', and 'my_real' to
        specialized floating-point types 'ale_real', 'ale_pos', 'ale_sreal',
        and 'ale_accum'.

o       Fix offset calculation in d2/render/ipc.h.  This is necessary for
        Irani-Peleg rendering of image mosaics extending upwards or to the
        left of the original frame.  (This fix is also included in a patch for
        0.5.1.)

o       Move classes treating snapshots as two-dimensional data to directory
        'd2' and create an associated C++ namespace.  We can't use '2d' to
        label the namespace, because the C++ grammar won't allow it.


0.5.1 2003-Nov-19

o       Several of the changes below are based on a suggestion by Bert
        Douglas regarding support for 16-bit-per-channel color.  See the README
        for more information about relevant compilation options.

o       Add information to the README regarding new compilation options.

o       Modify the makefile to accept a variable BITS, and differentiate between
        values BITS=8 and BITS=16.  The latter option causes the macro BITS_16
        to be defined during compilation.
        
o       Modify image_rw.h to handle 16-bit data when BITS_16 is defined.  Also,
        differentiate between 8-bit and 16-bit ImageMagick builds by checking
        MaxRGB.

o       In ppm.h, add carriage returns to the set of recognized whitespace
        characters.

o       Modify ppm.h to read 16-bit binary PPM files (added to the PPM format
        spec in April 2000).  

o       Modify ppm.h to read plain (ASCII) as well as raw (binary) PPM files.  

o       Add a Makefile option for writing plain (ASCII) PPM files instead of
        raw (binary).  This option causes the macro PPM_PLAIN to be defined
        during compilation.
        
o       Modify ppm.h to write plain (ASCII) PPM files when PPM_PLAIN is defined.

o       Modify ppm.h to output 16-bit PPM files when BITS_16 is defined.

o       Modify ppm.h to scale input intensity values based on the internal
        representation depth (8 or 16 bits per channel).

o       Add a file 'channel.h' to describe the color channel data type and
        valid range, both being dependent on whether BITS_16 is defined.  Use
        these generic values, where appropriate, throughout the ALE codebase.


0.5.0 2003-Nov-02

o       Remove certain cloning operations from align.h, but since cursory tests
        indicate that scaling with --scale is much more expensive than cloning,
        allow cloning to occur when scaling occurs.

o       Add more comment documentation to header files.

o       Emit a more informative error message when the PPM file handler
        encounters a file that is not a well-formed PPM binary file.

o       Move rendering implementations to subdirectory 'render/'.

o       Modify semantics of alignment following by applying to file-loaded
        initial transformations a delta transformation D = AB^-1, where B is
        the previous frame's (unmodified) initial transformation, A is the
        previous frame's final transformation, and ^-1 is the inverse operator.
        Using --follow with --trans-load can now improve alignment success when
        working with panoramic image mosaics.

o       We're not using simulated annealing, so remove comments that claim
        otherwise.

o       Remove certain unsafe assumptions from ipc/* (now render/ipc/*); this
        change includes a modification to ipc.h (now render/ipc.h).  Limits of
        the rectangle used as an argument to the <type>::response() function
        are now explicitly given rather than implied.

o       Change documentation for --replace.


0.4.8 2003-Aug-01

o       Modify Irani-Peleg renderer to produce incremental output.

o       Modify Monte Carlo alignment so that the same set of accumulated image
        pixels is examined when comparing two transformations.

o       Add an option for additional upper-bound constraint of rotational
        perturbation.  Jeff Epler had noted that the
        perturb-upper/perturb-lower options alone may not be suited to working
        with sets of higher-resolution images.  

o       Resolve a bug introduced in version 0.1.1 which had limited rotational
        perturbation to 2 degrees.

o       Add an option to adjust the maximum level of detail used.  The default
        maximum is 2/perturb, which matches the default for previous versions
        of ALE.

o       Modify names of temporary files used in the calibration script.


0.4.7 2003-Jul-27

o       Add a replacement option suggested by Jeff Treece.  This option can
        be used to facilitate video stabilization.

o       Irani-Peleg: add support for configurable modules, including 
        a module that reads its configuration data from standard input
        and a module calibrated for an IBM (Xirlink) XVP610 in 320x240
        mode.  A rudimentary script for calibrating devices with unknown
        projection functions has been included as ipc/ale-calibrate.

o       Irani-Peleg: don't truncate correction values in backprojection.

o       Irani-Peleg: don't multiply the weight function by a scale correction
        factor in backprojection.

o       Rename render::operator()() to render::sync().  Update subclasses
        accordingly.


0.4.6 2003-Jul-01

o       Allow --ip and --hf-enhance to be used together.  [Modify
        ip::operator() and hf_filter::operator() so that multiple
        post-processing filters can be used.]

o       Initialize the drizzled image to be uniformly black.  This fixes
        a bug introduced in 0.4.2.

o       Allocate the correct size image for drizzling.  This fixes a bug
        introduced in 0.4.5.


0.4.5 2003-Jun-23

o       Ensure correct transformation scaling and difference calculation after
        alignment is complete, even if alignment terminates with a reduced
        level of detail (i.e. perturb-lower > 2).

o       Separate the scale() function into two cases: scale() is reserved for
        scale factors greater than or equal to one, as in user-specified
        scaling; and scale_by_half() is used for the scale factor 0.5, needed
        to provide multiple levels of detail in alignment.  Modify the
        scale_by_half() case to reflect source pixel values more fairly.  (This
        change affects alignment behavior at reduced levels of detail.)

o       Reduce whitespace in usage() message.

o       Modify align::diff() to use correctly scaled image offset values.
        (Bugfix for alignment with --extend.)

o       Modify align.h so that the image definition array is correctly scaled
        for all levels of detail.  (Bugfix for alignment with --extend.)

o       Modify image.h to correctly handle image offset values.  (Bugfix
        for --extend operation.)

o       Remove call to stat() in image_rw.h.  This improves OS independence,
        and apparently also allows URL-specification of images when compiled
        with ImageMagick support.

o       Modify image file handler interface so that input files are not scaled.
        Perform scaling, when necessary, outside of the file handler.  Since
        unscaled data is needed by the drizzling and Irani-Peleg code, this
        fixes bugs in those modules.  


0.4.4 2003-Jun-06

o       Modify the Monte Carlo pixel selection algorithm so that the expected
        number of sampled pixels more closely matches the specified number in
        typical cases.

o       Specify the binary mode flag to fopen() calls in the PPM file handler.
        This change resolves a bug discovered by Benjamin Hill.


0.4.3 2003-May-30

o       Add support for Monte Carlo alignment of images, in which only a
        random subset of pixels is sampled.

o       Add an option to disable incremental image output.


0.4.2 2003-May-23

o       Implement an image reconstruction option based on the work of Irani and
        Peleg.

o       Clean up source; move rendering and alignment functions into separate
        files.

o       Change valid drizzling diameter interval to (0,1].

o       Modify PPM file reader to correctly handle comments in PPM files; this
        resolves a bug pointed out by Benjamin Hill.

o       Add missing typecast to resolve compile warning under GCC 3.2.

o       Make changes to gpt.h that may reduce the Euclidean alignment time.

o       Move ale.c to ale.cc to follow one of the many C++ naming conventions.


0.4.1 2003-Apr-28

o       Change language to C++.

o       Code cleanup in ale.c, image.h, and gpt.h.

o       Separate into a number of subsections the option descriptions in the
        README 

o       Add URL information to README

o       Add an experimental drizzling implementation.  Research on drizzling
        by Richard Hook and Andrew Fruchter was brought to the attention of 
        the author by Dan Kaminsky.

o       Add an option to use the previous frame's final transformation as the
        default alignment.

o       Change pixel weight data type so that more than 255 images can
        be merged.

o       Add support for increased spatial extents.  Research on increased
        spatial extents by Steve Mann was brought to the attention of the
        author by Dan Egnor.

o       Modify the transformation algorithm to use transformations from the
        domain of the input image to the range of the target image.  This
        change is reflected in transformation files.  Maintain support for
        old transformation file versions, however.

o       Add version information to transformation files and update the version
        from 0 to 2.


0.4.0p1 2003-Apr-04

o       Merge a bugfix from Debian ALE package version 0.4.0-1.  Without this
        fix, an assertion failure can occur when ImageMagick support is
        enabled.  Original fix implemented by Nick Rusnov.  


0.4.0 2003-Mar-30

o       Add support for general scaling parameters (i.e. all scale 
        factors >= 1.0).  --scale2, --scale4, and --scale8 are now deprecated, 
        and replaced with a more general --scale=x argument.

o       Support enhancement of high frequencies even when the scale factor is 
        1.0.

o       Modify the high-frequency filter algorithm to support filtering near
        the border of an image.

o       Modify the high-frequency filter function so that the response is now
        (4/n)^2 times what it used to be, where n is the scale factor.  


0.3.2 2003-Mar-26

o       Don't filter high frequencies if we're not enhancing them.  This 
        improves efficiency, but should not affect output.



0.3.1 2003-Mar-25

o       Output average match statistic.

o       Update informational output to transformation files to include original 
        frame.

o       Add support for post-enhancement of high-frequency details.


0.3.0 2003-Jan-17

o       Add support for loading and saving transformation data.

o       Add an option to set the upper bound on correction steps.

o       Modify Makefile to compile with size optimization, since this 
        appears to improve speed characteristics in some cases.

o       Move transformation data structure and related functions to 
        a separate header file.


0.2.0 2003-Jan-01

o       Add support for general projective transformations, and change/add
        options as follows:

                '--translation' used to be      '--no-rotate'
                '--euclidean'   used to be      '--rotate'
                '--projective'  is a new option


0.1.2 2002-Dec-13

o       Add optional support for .jpg, .png, .tiff, and other file formats
        through ImageMagick.  Translation using ImageMagick was suggested by
        Nick Rusnov.

o       Don't segfault if a file can't be opened.


0.1.1 2002-Dec-09

o       Use reduced levels of detail in coarser alignment steps to increase
        speed.

o       Change perturbation step lower-bound check from less-than ('<') to 
        less-than-or-equal-to ('<=').  Change default lower bound
        to .125 from .1 (the behavior is the same, but the value
        makes more sense).

o       Change perturbation initial value to 32 pixels from
        16 pixels, since coarse alignment is now less expensive.

o       Modify scale function so that the borders aren't 
        corrupted (too badly).


0.1.0 2002-Nov-26

o       Add support for correction of rotation about the lens axis.

o       Add an optional match criterion for merging.

o       Add an option to adjust minimum step-size.

o       Add flags to specify which channels to use for alignment.  Use
        a summation of all channels by default.

o       Add an option to modify the error metric exponent, and change
        the default value from 1 to 2. 

o       Display information about how well a new image matches
        the accumulated image.

o       Add a rule for ale.exe to the Makefile.  


0.0.0 2002-Oct-11

o       Initial release.