Updates libjpeg-turbo to 1.1.90 (r677)

third_party/libjpeg_turbo/turbojpeg.h

-/* Copyright (C)2004 Landmark Graphics Corporation
- * Copyright (C)2005, 2006 Sun Microsystems, Inc.
- * Copyright (C)2009 D. R. Commander
- *
- * This library is free software and may be redistributed and/or modified under
- * the terms of the wxWindows Library License, Version 3.1 or (at your option)
- * any later version.  The full license is in the LICENSE.txt file included
- * with this distribution.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * wxWindows Library License for more details.
- */
-
-#if (defined(_MSC_VER) || defined(__CYGWIN__) || defined(__MINGW32__)) && defined(_WIN32) && defined(DLLDEFINE)
+/*
+ * Copyright (C)2009-2011 D. R. Commander.  All Rights Reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * - Redistributions of source code must retain the above copyright notice,
+ *   this list of conditions and the following disclaimer.
+ * - Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ * - Neither the name of the libjpeg-turbo Project nor the names of its
+ *   contributors may be used to endorse or promote products derived from this
+ *   software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS",
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef __TURBOJPEG_H__
+#define __TURBOJPEG_H__
+
+#if defined(_WIN32) && defined(DLLDEFINE)
 #define DLLEXPORT __declspec(dllexport)
 #else
 #define DLLEXPORT
 #endif
-
 #define DLLCALL
 
-/* Subsampling */
-#define NUMSUBOPT 4
-
-enum {TJ_444=0, TJ_422, TJ_420, TJ_GRAYSCALE};
-#define TJ_411 TJ_420  /* for backward compatibility with VirtualGL <= 2.1.x,
-                          TurboVNC <= 0.6, and TurboJPEG/IPP */
-
-/* Flags */
-#define TJ_BGR             1
-  /* The components of each pixel in the source/destination bitmap are stored
-     in B,G,R order, not R,G,B */
-#define TJ_BOTTOMUP        2
-  /* The source/destination bitmap is stored in bottom-up (Windows, OpenGL)
-     order, not top-down (X11) order */
-#define TJ_FORCEMMX        8
-  /* Turn off CPU auto-detection and force TurboJPEG to use MMX code
-     (IPP and 32-bit libjpeg-turbo versions only) */
-#define TJ_FORCESSE       16
-  /* Turn off CPU auto-detection and force TurboJPEG to use SSE code
-     (32-bit IPP and 32-bit libjpeg-turbo versions only) */
-#define TJ_FORCESSE2      32
-  /* Turn off CPU auto-detection and force TurboJPEG to use SSE2 code
-     (32-bit IPP and 32-bit libjpeg-turbo versions only) */
-#define TJ_ALPHAFIRST     64
-  /* If the source/destination bitmap is 32 bpp, assume that each pixel is
-     ARGB/XRGB (or ABGR/XBGR if TJ_BGR is also specified) */
-#define TJ_FORCESSE3     128
-  /* Turn off CPU auto-detection and force TurboJPEG to use SSE3 code
-     (64-bit IPP version only) */
-#define TJ_FASTUPSAMPLE  256
-  /* Use fast, inaccurate 4:2:2 and 4:2:0 YUV upsampling routines
-     (libjpeg version only) */
+
+/**
+ * @addtogroup TurboJPEG
+ * TurboJPEG API.  This API provides an interface for generating, decoding, and
+ * transforming planar YUV and JPEG images in memory.
+ *
+ * @{
+ */
+
+
+/**
+ * The number of chrominance subsampling options
+ */
+#define TJ_NUMSAMP 5
+
+/**
+ * Chrominance subsampling options.
+ * When an image is converted from the RGB to the YCbCr colorspace as part of
+ * the JPEG compression process, some of the Cb and Cr (chrominance) components
+ * can be discarded or averaged together to produce a smaller image with little
+ * perceptible loss of image clarity (the human eye is more sensitive to small
+ * changes in brightness than small changes in color.)  This is called
+ * "chrominance subsampling".
+ */
+enum TJSAMP
+{
+  /**
+   * 4:4:4 chrominance subsampling (no chrominance subsampling).  The JPEG or
+   * YUV image will contain one chrominance component for every pixel in the
+   * source image.
+   */
+  TJSAMP_444=0,
+  /**
+   * 4:2:2 chrominance subsampling.  The JPEG or YUV image will contain one
+   * chrominance component for every 2x1 block of pixels in the source image.
+   */
+  TJSAMP_422,
+  /**
+   * 4:2:0 chrominance subsampling.  The JPEG or YUV image will contain one
+   * chrominance component for every 2x2 block of pixels in the source image.
+   */
+  TJSAMP_420,
+  /**
+   * Grayscale.  The JPEG or YUV image will contain no chrominance components.
+   */
+  TJSAMP_GRAY,
+  /**
+   * 4:4:0 chrominance subsampling.  The JPEG or YUV image will contain one
+   * chrominance component for every 1x2 block of pixels in the source image.
+   */
+  TJSAMP_440
+};
+
+/**
+ * MCU block width (in pixels) for a given level of chrominance subsampling.
+ * MCU block sizes:
+ * - 8x8 for no subsampling or grayscale
+ * - 16x8 for 4:2:2
+ * - 8x16 for 4:4:0
+ * - 16x16 for 4:2:0 
+ */
+static const int tjMCUWidth[TJ_NUMSAMP]  = {8, 16, 16, 8, 8};
+
+/**
+ * MCU block height (in pixels) for a given level of chrominance subsampling.
+ * MCU block sizes:
+ * - 8x8 for no subsampling or grayscale
+ * - 16x8 for 4:2:2
+ * - 8x16 for 4:4:0
+ * - 16x16 for 4:2:0 
+ */
+static const int tjMCUHeight[TJ_NUMSAMP] = {8, 8, 16, 8, 16};
+
+
+/**
+ * The number of pixel formats
+ */
+#define TJ_NUMPF 7
+
+/**
+ * Pixel formats
+ */
+enum TJPF
+{
+  /**
+   * RGB pixel format.  The red, green, and blue components in the image are
+   * stored in 3-byte pixels in the order R, G, B from lowest to highest byte
+   * address within each pixel.
+   */
+  TJPF_RGB=0,
+  /**
+   * BGR pixel format.  The red, green, and blue components in the image are
+   * stored in 3-byte pixels in the order B, G, R from lowest to highest byte
+   * address within each pixel.
+   */
+  TJPF_BGR,
+  /**
+   * RGBX pixel format.  The red, green, and blue components in the image are
+   * stored in 4-byte pixels in the order R, G, B from lowest to highest byte
+   * address within each pixel.
+   */
+  TJPF_RGBX,
+  /**
+   * BGRX pixel format.  The red, green, and blue components in the image are
+   * stored in 4-byte pixels in the order B, G, R from lowest to highest byte
+   * address within each pixel.
+   */
+  TJPF_BGRX,
+  /**
+   * XBGR pixel format.  The red, green, and blue components in the image are
+   * stored in 4-byte pixels in the order R, G, B from highest to lowest byte
+   * address within each pixel.
+   */
+  TJPF_XBGR,
+  /**
+   * XRGB pixel format.  The red, green, and blue components in the image are
+   * stored in 4-byte pixels in the order B, G, R from highest to lowest byte
+   * address within each pixel.
+   */
+  TJPF_XRGB,
+  /**
+   * Grayscale pixel format.  Each 1-byte pixel represents a luminance
+   * (brightness) level from 0 to 255.
+   */
+  TJPF_GRAY
+};
+
+/**
+ * Red offset (in bytes) for a given pixel format.  This specifies the number
+ * of bytes that the red component is offset from the start of the pixel.  For
+ * instance, if a pixel of format TJ_BGRX is stored in <tt>char pixel[]</tt>,
+ * then the red component will be <tt>pixel[tjRedOffset[TJ_BGRX]]</tt>.
+ */
+static const int tjRedOffset[TJ_NUMPF] = {0, 2, 0, 2, 3, 1, 0};
+/**
+ * Green offset (in bytes) for a given pixel format.  This specifies the number
+ * of bytes that the green component is offset from the start of the pixel.
+ * For instance, if a pixel of format TJ_BGRX is stored in
+ * <tt>char pixel[]</tt>, then the green component will be
+ * <tt>pixel[tjGreenOffset[TJ_BGRX]]</tt>.
+ */
+static const int tjGreenOffset[TJ_NUMPF] = {1, 1, 1, 1, 2, 2, 0};
+/**
+ * Blue offset (in bytes) for a given pixel format.  This specifies the number
+ * of bytes that the Blue component is offset from the start of the pixel.  For
+ * instance, if a pixel of format TJ_BGRX is stored in <tt>char pixel[]</tt>,
+ * then the blue component will be <tt>pixel[tjBlueOffset[TJ_BGRX]]</tt>.
+ */
+static const int tjBlueOffset[TJ_NUMPF] = {2, 0, 2, 0, 1, 3, 0};
+
+/**
+ * Pixel size (in bytes) for a given pixel format.
+ */
+static const int tjPixelSize[TJ_NUMPF] = {3, 3, 4, 4, 4, 4, 1};
+
+
+/**
+ * The uncompressed source/destination image is stored in bottom-up (Windows,
+ * OpenGL) order, not top-down (X11) order.
+ */
+#define TJFLAG_BOTTOMUP        2
+/**
+ * Turn off CPU auto-detection and force TurboJPEG to use MMX code (IPP and
+ * 32-bit libjpeg-turbo versions only.)
+ */
+#define TJFLAG_FORCEMMX        8
+/**
+ * Turn off CPU auto-detection and force TurboJPEG to use SSE code (32-bit IPP
+ * and 32-bit libjpeg-turbo versions only)
+ */
+#define TJFLAG_FORCESSE       16
+/**
+ * Turn off CPU auto-detection and force TurboJPEG to use SSE2 code (32-bit IPP
+ * and 32-bit libjpeg-turbo versions only)
+ */
+#define TJFLAG_FORCESSE2      32
+/**
+ * Turn off CPU auto-detection and force TurboJPEG to use SSE3 code (64-bit IPP
+ * version only)
+ */
+#define TJFLAG_FORCESSE3     128
+/**
+ * Use fast, inaccurate chrominance upsampling routines in the JPEG
+ * decompressor (libjpeg and libjpeg-turbo versions only)
+ */
+#define TJFLAG_FASTUPSAMPLE  256
+/**
+ * Disable buffer (re)allocation.  If passed to #tjCompress2() or
+ * #tjTransform(), this flag will cause those functions to generate an error if
+ * the JPEG image buffer is invalid or too small rather than attempting to
+ * allocate or reallocate that buffer.  This reproduces the behavior of earlier
+ * versions of TurboJPEG.
+ */
+#define TJFLAG_NOREALLOC     1024
+
+
+/**
+ * Number of transform operations
+ */
+#define TJ_NUMXOP 8
+
+/**
+ * Transform operations for #tjTransform()
+ */
+enum TJXOP
+{
+  /**
+   * Do not transform the position of the image pixels
+   */
+  TJXOP_NONE=0,
+  /**
+   * Flip (mirror) image horizontally.  This transform is imperfect if there
+   * are any partial MCU blocks on the right edge (see #TJXOPT_PERFECT.)
+   */
+  TJXOP_HFLIP,
+  /**
+   * Flip (mirror) image vertically.  This transform is imperfect if there are
+   * any partial MCU blocks on the bottom edge (see #TJXOPT_PERFECT.)
+   */
+  TJXOP_VFLIP,
+  /**
+   * Transpose image (flip/mirror along upper left to lower right axis.)  This
+   * transform is always perfect.
+   */
+  TJXOP_TRANSPOSE,
+  /**
+   * Transverse transpose image (flip/mirror along upper right to lower left
+   * axis.)  This transform is imperfect if there are any partial MCU blocks in
+   * the image (see #TJXOPT_PERFECT.)
+   */
+  TJXOP_TRANSVERSE,
+  /**
+   * Rotate image clockwise by 90 degrees.  This transform is imperfect if
+   * there are any partial MCU blocks on the bottom edge (see
+   * #TJXOPT_PERFECT.)
+   */
+  TJXOP_ROT90,
+  /**
+   * Rotate image 180 degrees.  This transform is imperfect if there are any
+   * partial MCU blocks in the image (see #TJXOPT_PERFECT.)
+   */
+  TJXOP_ROT180,
+  /**
+   * Rotate image counter-clockwise by 90 degrees.  This transform is imperfect
+   * if there are any partial MCU blocks on the right edge (see
+   * #TJXOPT_PERFECT.)
+   */
+  TJXOP_ROT270
+};
+
+
+/**
+ * This option will cause #tjTransform() to return an error if the transform is
+ * not perfect.  Lossless transforms operate on MCU blocks, whose size depends
+ * on the level of chrominance subsampling used (see #tjMCUWidth
+ * and #tjMCUHeight.)  If the image's width or height is not evenly divisible
+ * by the MCU block size, then there will be partial MCU blocks on the right
+ * and/or bottom edges.  It is not possible to move these partial MCU blocks to
+ * the top or left of the image, so any transform that would require that is
+ * "imperfect."  If this option is not specified, then any partial MCU blocks
+ * that cannot be transformed will be left in place, which will create
+ * odd-looking strips on the right or bottom edge of the image.
+ */
+#define TJXOPT_PERFECT  1
+/**
+ * This option will cause #tjTransform() to discard any partial MCU blocks that
+ * cannot be transformed.
+ */
+#define TJXOPT_TRIM     2
+/**
+ * This option will enable lossless cropping.  See #tjTransform() for more
+ * information.
+ */
+#define TJXOPT_CROP     4
+/**
+ * This option will discard the color data in the input image and produce
+ * a grayscale output image.
+ */
+#define TJXOPT_GRAY     8
+
+
+/**
+ * Scaling factor
+ */
+typedef struct
+{
+  /**
+   * Numerator
+   */
+  int num;
+  /**
+   * Denominator
+   */
+  int denom;
+} tjscalingfactor;
+
+/**
+ * Cropping region
+ */
+typedef struct
+{
+  /**
+   * The left boundary of the cropping region.  This must be evenly divisible
+   * by the MCU block width (see #tjMCUWidth.)
+   */
+  int x;
+  /**
+   * The upper boundary of the cropping region.  This must be evenly divisible
+   * by the MCU block height (see #tjMCUHeight.)
+   */
+  int y;
+  /**
+   * The width of the cropping region. Setting this to 0 is the equivalent of
+   * setting it to the width of the source JPEG image - x.
+   */
+  int w;
+  /**
+   * The height of the cropping region. Setting this to 0 is the equivalent of
+   * setting it to the height of the source JPEG image - y.
+   */
+  int h;
+} tjregion;
+
+/**
+ * Lossless transform
+ */
+typedef struct
+{
+  /**
+   * Cropping region
+   */
+  tjregion r;
+  /**
+   * One of the @ref TJXOP "transform operations"
+   */
+  int op;
+  /**
+   * The bitwise OR of one of more of the @ref TJXOPT_CROP "transform options"
+   */
+  int options;
+} tjtransform;
+
+/**
+ * TurboJPEG instance handle
+ */
 typedef void* tjhandle;
 
-#define TJPAD(p) (((p)+3)&(~3))
-#ifndef max
- #define max(a,b) ((a)>(b)?(a):(b))
-#endif
+
+/**
+ * Pad the given width to the nearest 32-bit boundary
+ */
+#define TJPAD(width) (((width)+3)&(~3))
+
+/**
+ * Compute the scaled value of <tt>dimension</tt> using the given scaling
+ * factor.  This macro performs the integer equivalent of <tt>ceil(dimension *
+ * scalingFactor)</tt>. 
+ */
+#define TJSCALED(dimension, scalingFactor) ((dimension * scalingFactor.num \
+  + scalingFactor.denom - 1) / scalingFactor.denom)
+
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-/* API follows */
-
-
-/*
-  tjhandle tjInitCompress(void)
-
-  Creates a new JPEG compressor instance, allocates memory for the structures,
-  and returns a handle to the instance.  Most applications will only
-  need to call this once at the beginning of the program or once for each
-  concurrent thread.  Don't try to create a new instance every time you
-  compress an image, because this will cause performance to suffer.
-
-  RETURNS: NULL on error
+
+/**
+ * Create a TurboJPEG compressor instance.
+ *
+ * @return a handle to the newly-created instance, or NULL if an error
+ * occurred (see #tjGetErrorStr().)
+ */
+DLLEXPORT tjhandle DLLCALL tjInitCompress(void);
+
+
+/**
+ * Compress an RGB or grayscale image into a JPEG image.
+ *
+ * @param handle a handle to a TurboJPEG compressor or transformer instance
+ * @param srcBuf pointer to an image buffer containing RGB or grayscale pixels
+ *        to be compressed
+ * @param width width (in pixels) of the source image
+ * @param pitch bytes per line of the source image.  Normally, this should be
+ *        <tt>width * #tjPixelSize[pixelFormat]</tt> if the image is unpadded,
+ *        or <tt>#TJPAD(width * #tjPixelSize[pixelFormat])</tt> if each line of
+ *        the image is padded to the nearest 32-bit boundary, as is the case
+ *        for Windows bitmaps.  You can also be clever and use this parameter
+ *        to skip lines, etc.  Setting this parameter to 0 is the equivalent of
+ *        setting it to <tt>width * #tjPixelSize[pixelFormat]</tt>.
+ * @param height height (in pixels) of the source image
+ * @param pixelFormat pixel format of the source image (see @ref TJPF
+ *        "Pixel formats".)
+ * @param jpegBuf address of a pointer to an image buffer that will receive the
+ *        JPEG image.  TurboJPEG has the ability to reallocate the JPEG buffer
+ *        to accommodate the size of the JPEG image.  Thus, you can choose to:
+ *        -# pre-allocate the JPEG buffer with an arbitrary size using
+ *        #tjAlloc() and let TurboJPEG grow the buffer as needed,
+ *        -# set <tt>*jpegBuf</tt> to NULL to tell TurboJPEG to allocate the
+ *        buffer for you, or
+ *        -# pre-allocate the buffer to a "worst case" size determined by
+ *        calling #tjBufSize().  This should ensure that the buffer never has
+ *        to be re-allocated (setting #TJFLAG_NOREALLOC guarantees this.)
+ *        .
+ *        If you choose option 1, <tt>*jpegSize</tt> should be set to the
+ *        size of your pre-allocated buffer.  In any case, unless you have
+ *        set #TJFLAG_NOREALLOC, you should always check <tt>*jpegBuf</tt> upon
+ *        return from this function, as it may have changed.
+ * @param jpegSize pointer to an unsigned long variable which holds the size of
+ *        the JPEG image buffer.  If <tt>*jpegBuf</tt> points to a
+ *        pre-allocated buffer, then <tt>*jpegSize</tt> should be set to the
+ *        size of the buffer.  Upon return, <tt>*jpegSize</tt> will contain the
+ *        size of the JPEG image (in bytes.)
+ * @param jpegSubsamp the level of chrominance subsampling to be used when
+ *        generating the JPEG image (see @ref TJSAMP
+ *        "Chrominance subsampling options".)
+ * @param jpegQual the image quality of the generated JPEG image (1 = worst,
+          100 = best)
+ * @param flags the bitwise OR of one or more of the @ref TJFLAG_BOTTOMUP
+ *        "flags".
+ *
+ * @return 0 if successful, or -1 if an error occurred (see #tjGetErrorStr().)
 */
-DLLEXPORT tjhandle DLLCALL tjInitCompress(void);
-
-
-/*
-  int tjCompress(tjhandle j,
-     unsigned char *srcbuf, int width, int pitch, int height, int pixelsize,
-     unsigned char *dstbuf, unsigned long *size,
-     int jpegsubsamp, int jpegqual, int flags)
-
-  [INPUT] j = instance handle previously returned from a call to
-     tjInitCompress()
-  [INPUT] srcbuf = pointer to user-allocated image buffer containing pixels in
-     RGB(A) or BGR(A) form
-  [INPUT] width =  width (in pixels) of the source image
-  [INPUT] pitch = bytes per line of the source image (width*pixelsize if the
-     bitmap is unpadded, else TJPAD(width*pixelsize) if each line of the bitmap
-     is padded to the nearest 32-bit boundary, such as is the case for Windows
-     bitmaps.  You can also be clever and use this parameter to skip lines, etc.,
-     as long as the pitch is greater than 0.)
-  [INPUT] height = height (in pixels) of the source image
-  [INPUT] pixelsize = size (in bytes) of each pixel in the source image
-     RGBA and BGRA: 4, RGB and BGR: 3
-  [INPUT] dstbuf = pointer to user-allocated image buffer which will receive
-     the JPEG image.  Use the macro TJBUFSIZE(width, height) to determine
-     the appropriate size for this buffer based on the image width and height.
-  [OUTPUT] size = pointer to unsigned long which receives the size (in bytes)
-     of the compressed image
-  [INPUT] jpegsubsamp = Specifies either 4:2:0, 4:2:2, or 4:4:4 subsampling.
-     When the image is converted from the RGB to YCbCr colorspace as part of the
-     JPEG compression process, every other Cb and Cr (chrominance) pixel can be
-     discarded to produce a smaller image with little perceptible loss of
-     image clarity (the human eye is more sensitive to small changes in
-     brightness than small changes in color.)
-
-     TJ_420: 4:2:0 subsampling.  Discards every other Cb, Cr pixel in both
-        horizontal and vertical directions.
-     TJ_422: 4:2:2 subsampling.  Discards every other Cb, Cr pixel only in
-        the horizontal direction.
-     TJ_444: no subsampling.
-     TJ_GRAYSCALE: Generate grayscale JPEG image
-
-  [INPUT] jpegqual = JPEG quality (an integer between 0 and 100 inclusive.)
-  [INPUT] flags = the bitwise OR of one or more of the flags described in the
-     "Flags" section above.
-
-  RETURNS: 0 on success, -1 on error
+DLLEXPORT int DLLCALL tjCompress2(tjhandle handle, unsigned char *srcBuf,
+  int width, int pitch, int height, int pixelFormat, unsigned char **jpegBuf,
+  unsigned long *jpegSize, int jpegSubsamp, int jpegQual, int flags);
+
+
+/**
+ * The maximum size of the buffer (in bytes) required to hold a JPEG image with
+ * the given parameters.  The number of bytes returned by this function is
+ * larger than the size of the uncompressed source image.  The reason for this
+ * is that the JPEG format uses 16-bit coefficients, and it is thus possible
+ * for a very high-quality JPEG image with very high frequency content to
+ * expand rather than compress when converted to the JPEG format.  Such images
+ * represent a very rare corner case, but since there is no way to predict the
+ * size of a JPEG image prior to compression, the corner case has to be
+ * handled.
+ *
+ * @param width width of the image (in pixels)
+ * @param height height of the image (in pixels)
+ * @param jpegSubsamp the level of chrominance subsampling to be used when
+ *        generating the JPEG image (see @ref TJSAMP
+ *        "Chrominance subsampling options".)
+ *
+ * @return the maximum size of the buffer (in bytes) required to hold the
+ * image, or -1 if the arguments are out of bounds.
+ */
+DLLEXPORT unsigned long DLLCALL tjBufSize(int width, int height,
+  int jpegSubsamp);
+
+
+/**
+ * The size of the buffer (in bytes) required to hold a YUV planar image with
+ * the given parameters.
+ *
+ * @param width width of the image (in pixels)
+ * @param height height of the image (in pixels)
+ * @param subsamp level of chrominance subsampling in the image (see
+ *        @ref TJSAMP "Chrominance subsampling options".)
+ *
+ * @return the size of the buffer (in bytes) required to hold the image, or
+ * -1 if the arguments are out of bounds.
+ */
+DLLEXPORT unsigned long DLLCALL tjBufSizeYUV(int width, int height,
+  int subsamp);
+
+
+/**
+ * Encode an RGB or grayscale image into a YUV planar image.  This function
+ * uses the accelerated color conversion routines in TurboJPEG's underlying
+ * codec to produce a planar YUV image that is suitable for X Video.
+ * Specifically, if the chrominance components are subsampled along the
+ * horizontal dimension, then the width of the luminance plane is padded to 2
+ * in the output image (same goes for the height of the luminance plane, if the
+ * chrominance components are subsampled along the vertical dimension.)  Also,
+ * each line of each plane in the output image is padded to 4 bytes.  Although
+ * this will work with any subsampling option, it is really only useful in
+ * combination with TJ_420, which produces an image compatible with the I420
+ * (AKA "YUV420P") format.
+ *
+ * @param handle a handle to a TurboJPEG compressor or transformer instance
+ * @param srcBuf pointer to an image buffer containing RGB or grayscale pixels
+ *        to be encoded
+ * @param width width (in pixels) of the source image
+ * @param pitch bytes per line of the source image.  Normally, this should be
+ *        <tt>width * #tjPixelSize[pixelFormat]</tt> if the image is unpadded,
+ *        or <tt>#TJPAD(width * #tjPixelSize[pixelFormat])</tt> if each line of
+ *        the image is padded to the nearest 32-bit boundary, as is the case
+ *        for Windows bitmaps.  You can also be clever and use this parameter
+ *        to skip lines, etc.  Setting this parameter to 0 is the equivalent of
+ *        setting it to <tt>width * #tjPixelSize[pixelFormat]</tt>.
+ * @param height height (in pixels) of the source image
+ * @param pixelFormat pixel format of the source image (see @ref TJPF
+ *        "Pixel formats".)
+ * @param dstBuf pointer to an image buffer which will receive the YUV image.
+ *        Use #tjBufSizeYUV() to determine the appropriate size for this buffer
+ *        based on the image width, height, and level of chrominance
+ *        subsampling.
+ * @param subsamp the level of chrominance subsampling to be used when
+ *        generating the YUV image (see @ref TJSAMP
+ *        "Chrominance subsampling options".)
+ * @param flags the bitwise OR of one or more of the @ref TJFLAG_BOTTOMUP
+ *        "flags".
+ *
+ * @return 0 if successful, or -1 if an error occurred (see #tjGetErrorStr().)
 */
-DLLEXPORT int DLLCALL tjCompress(tjhandle j,
-        unsigned char *srcbuf, int width, int pitch, int height, int pixelsize,
-        unsigned char *dstbuf, unsigned long *size,
-        int jpegsubsamp, int jpegqual, int flags);
-
-DLLEXPORT unsigned long DLLCALL TJBUFSIZE(int width, int height);
-
-/*
-  tjhandle tjInitDecompress(void)
-
-  Creates a new JPEG decompressor instance, allocates memory for the
-  structures, and returns a handle to the instance.  Most applications will
-  only need to call this once at the beginning of the program or once for each
-  concurrent thread.  Don't try to create a new instance every time you
-  decompress an image, because this will cause performance to suffer.
-
-  RETURNS: NULL on error
+DLLEXPORT int DLLCALL tjEncodeYUV2(tjhandle handle,
+  unsigned char *srcBuf, int width, int pitch, int height, int pixelFormat,
+  unsigned char *dstBuf, int subsamp, int flags);
+
+
+/**
+ * Create a TurboJPEG decompressor instance.
+ *
+ * @return a handle to the newly-created instance, or NULL if an error
+ * occurred (see #tjGetErrorStr().)
 */
 DLLEXPORT tjhandle DLLCALL tjInitDecompress(void);
 
 
-/*
-  int tjDecompressHeader(tjhandle j,
-     unsigned char *srcbuf, unsigned long size,
-     int *width, int *height)
-
-  [INPUT] j = instance handle previously returned from a call to
-     tjInitDecompress()
-  [INPUT] srcbuf = pointer to a user-allocated buffer containing the JPEG image
-     to decompress
-  [INPUT] size = size of the JPEG image buffer (in bytes)
-  [OUTPUT] width = width (in pixels) of the JPEG image
-  [OUTPUT] height = height (in pixels) of the JPEG image
-
-  RETURNS: 0 on success, -1 on error
+/**
+ * Retrieve information about a JPEG image without decompressing it.
+ *
+ * @param handle a handle to a TurboJPEG decompressor or transformer instance
+ * @param jpegBuf pointer to a buffer containing a JPEG image
+ * @param jpegSize size of the JPEG image (in bytes)
+ * @param width pointer to an integer variable which will receive the width (in
+ *        pixels) of the JPEG image
+ * @param height pointer to an integer variable which will receive the height
+ *        (in pixels) of the JPEG image
+ * @param jpegSubsamp pointer to an integer variable which will receive the
+ *        level of chrominance subsampling used when compressing the JPEG image
+ *        (see @ref TJSAMP "Chrominance subsampling options".)
+ *
+ * @return 0 if successful, or -1 if an error occurred (see #tjGetErrorStr().)
 */
-DLLEXPORT int DLLCALL tjDecompressHeader(tjhandle j,
-        unsigned char *srcbuf, unsigned long size,
-        int *width, int *height);
-
-
-/*
-  int tjDecompress(tjhandle j,
-     unsigned char *srcbuf, unsigned long size,
-     unsigned char *dstbuf, int width, int pitch, int height, int pixelsize,
-     int flags)
-
-  [INPUT] j = instance handle previously returned from a call to
-     tjInitDecompress()
-  [INPUT] srcbuf = pointer to a user-allocated buffer containing the JPEG image
-     to decompress
-  [INPUT] size = size of the JPEG image buffer (in bytes)
-  [INPUT] dstbuf = pointer to user-allocated image buffer which will receive
-     the bitmap image.  This buffer should normally be pitch*height
-     bytes in size, although this pointer may also be used to decompress into
-     a specific region of a larger buffer.
-  [INPUT] width =  width (in pixels) of the destination image
-  [INPUT] pitch = bytes per line of the destination image (width*pixelsize if the
-     bitmap is unpadded, else TJPAD(width*pixelsize) if each line of the bitmap
-     is padded to the nearest 32-bit boundary, such as is the case for Windows
-     bitmaps.  You can also be clever and use this parameter to skip lines, etc.,
-     as long as the pitch is greater than 0.)
-  [INPUT] height = height (in pixels) of the destination image
-  [INPUT] pixelsize = size (in bytes) of each pixel in the destination image
-     RGBA/RGBx and BGRA/BGRx: 4, RGB and BGR: 3
-  [INPUT] flags = the bitwise OR of one or more of the flags described in the
-     "Flags" section above.
-
-  RETURNS: 0 on success, -1 on error
+DLLEXPORT int DLLCALL tjDecompressHeader2(tjhandle handle,
+  unsigned char *jpegBuf, unsigned long jpegSize, int *width, int *height,
+  int *jpegSubsamp);
+
+
+/**
+ * Returns a list of fractional scaling factors that the JPEG decompressor in
+ * this implementation of TurboJPEG supports.
+ *
+ * @param numscalingfactors pointer to an integer variable that will receive
+ *        the number of elements in the list
+ *
+ * @return a pointer to a list of fractional scaling factors, or NULL if an
+ * error is encountered (see #tjGetErrorStr().)
 */
-DLLEXPORT int DLLCALL tjDecompress(tjhandle j,
-        unsigned char *srcbuf, unsigned long size,
-        unsigned char *dstbuf, int width, int pitch, int height, int pixelsize,
-        int flags);
-
-
-/*
-  int tjDestroy(tjhandle h)
-
-  Frees structures associated with a compression or decompression instance
-  
-  [INPUT] h = instance handle (returned from a previous call to
-     tjInitCompress() or tjInitDecompress()
-
-  RETURNS: 0 on success, -1 on error
-*/
-DLLEXPORT int DLLCALL tjDestroy(tjhandle h);
-
-
-/*
-  char *tjGetErrorStr(void)
-  
-  Returns a descriptive error message explaining why the last command failed
-*/
+DLLEXPORT tjscalingfactor* DLLCALL tjGetScalingFactors(int *numscalingfactors);
+
+
+/**
+ * Decompress a JPEG image to an RGB or grayscale image.
+ *
+ * @param handle a handle to a TurboJPEG decompressor or transformer instance
+ * @param jpegBuf pointer to a buffer containing the JPEG image to decompress
+ * @param jpegSize size of the JPEG image (in bytes)
+ * @param dstBuf pointer to an image buffer which will receive the decompressed
+ *        image.  This buffer should normally be <tt>pitch * scaledHeight</tt>
+ *        bytes in size, where <tt>scaledHeight</tt> can be determined by
+ *        calling #TJSCALED() with the JPEG image height and one of the scaling
+ *        factors returned by #tjGetScalingFactors().  The dstBuf pointer may
+ *        also be used to decompress into a specific region of a larger buffer.
+ * @param width desired width (in pixels) of the destination image.  If this is
+ *        smaller than the width of the JPEG image being decompressed, then
+ *        TurboJPEG will use scaling in the JPEG decompressor to generate the
+ *        largest possible image that will fit within the desired width.  If
+ *        width is set to 0, then only the height will be considered when
+ *        determining the scaled image size.
+ * @param pitch bytes per line of the destination image.  Normally, this is
+ *        <tt>scaledWidth * #tjPixelSize[pixelFormat]</tt> if the decompressed
+ *        image is unpadded, else <tt>#TJPAD(scaledWidth *
+ *        #tjPixelSize[pixelFormat])</tt> if each line of the decompressed
+ *        image is padded to the nearest 32-bit boundary, as is the case for
+ *        Windows bitmaps.  (NOTE: <tt>scaledWidth</tt> can be determined by
+ *        calling #TJSCALED() with the JPEG image width and one of the scaling
+ *        factors returned by #tjGetScalingFactors().)  You can also be clever
+ *        and use the pitch parameter to skip lines, etc.  Setting this
+ *        parameter to 0 is the equivalent of setting it to <tt>scaledWidth
+ *        * #tjPixelSize[pixelFormat]</tt>.
+ * @param height desired height (in pixels) of the destination image.  If this
+ *        is smaller than the height of the JPEG image being decompressed, then
+ *        TurboJPEG will use scaling in the JPEG decompressor to generate the
+ *        largest possible image that will fit within the desired height.  If
+ *        height is set to 0, then only the width will be considered when
+ *        determining the scaled image size.
+ * @param pixelFormat pixel format of the destination image (see @ref
+ *        TJPF "Pixel formats".)
+ * @param flags the bitwise OR of one or more of the @ref TJFLAG_BOTTOMUP
+ *        "flags".
+ *
+ * @return 0 if successful, or -1 if an error occurred (see #tjGetErrorStr().)
+ */
+DLLEXPORT int DLLCALL tjDecompress2(tjhandle handle,
+  unsigned char *jpegBuf, unsigned long jpegSize, unsigned char *dstBuf,
+  int width, int pitch, int height, int pixelFormat, int flags);
+
+
+/**
+ * Decompress a JPEG image to a YUV planar image.  This function performs JPEG
+ * decompression but leaves out the color conversion step, so a planar YUV
+ * image is generated instead of an RGB image.  The padding of the planes in
+ * this image is the same as the images generated by #tjEncodeYUV2().  Note
+ * that, if the width or height of the image is not an even multiple of the MCU
+ * block size (see #tjMCUWidth and #tjMCUHeight), then an intermediate buffer
+ * copy will be performed within TurboJPEG.
+ *
+ * @param handle a handle to a TurboJPEG decompressor or transformer instance
+ * @param jpegBuf pointer to a buffer containing the JPEG image to decompress
+ * @param jpegSize size of the JPEG image (in bytes)
+ * @param dstBuf pointer to an image buffer which will receive the YUV image.
+ *        Use #tjBufSizeYUV to determine the appropriate size for this buffer
+ *        based on the image width, height, and level of subsampling.
+ * @param flags the bitwise OR of one or more of the @ref TJFLAG_BOTTOMUP
+ *        "flags".
+ *
+ * @return 0 if successful, or -1 if an error occurred (see #tjGetErrorStr().)
+ */
+DLLEXPORT int DLLCALL tjDecompressToYUV(tjhandle handle,
+  unsigned char *jpegBuf, unsigned long jpegSize, unsigned char *dstBuf,
+  int flags);
+
+
+/**
+ * Create a new TurboJPEG transformer instance.
+ *
+ * @return a handle to the newly-created instance, or NULL if an error
+ * occurred (see #tjGetErrorStr().)
+ */
+DLLEXPORT tjhandle DLLCALL tjInitTransform(void);
+
+
+/**
+ * Losslessly transform a JPEG image into another JPEG image.  Lossless
+ * transforms work by moving the raw coefficients from one JPEG image structure
+ * to another without altering the values of the coefficients.  While this is
+ * typically faster than decompressing the image, transforming it, and
+ * re-compressing it, lossless transforms are not free.  Each lossless
+ * transform requires reading and Huffman decoding all of the coefficients in
+ * the source image, regardless of the size of the destination image.  Thus,
+ * this function provides a means of generating multiple transformed images
+ * from the same source or of applying multiple transformations simultaneously,
+ * in order to eliminate the need to read the source coefficients multiple
+ * times.
+ *
+ * @param handle a handle to a TurboJPEG transformer instance
+ * @param jpegBuf pointer to a buffer containing the JPEG image to transform
+ * @param jpegSize size of the JPEG image (in bytes)
+ * @param n the number of transformed JPEG images to generate
+ * @param dstBufs pointer to an array of n image buffers.  <tt>dstBufs[i]</tt>
+ *        will receive a JPEG image that has been transformed using the
+ *        parameters in <tt>transforms[i]</tt>.  TurboJPEG has the ability to
+ *        reallocate the JPEG buffer to accommodate the size of the JPEG image.
+ *        Thus, you can choose to:
+ *        -# pre-allocate the JPEG buffer with an arbitrary size using
+ *        #tjAlloc() and let TurboJPEG grow the buffer as needed,
+ *        -# set <tt>dstBufs[i]</tt> to NULL to tell TurboJPEG to allocate the
+ *        buffer for you, or
+ *        -# pre-allocate the buffer to a "worst case" size determined by
+ *        calling #tjBufSize() with the cropped width and height.  This should
+ *        ensure that the buffer never has to be re-allocated (setting
+ *        #TJFLAG_NOREALLOC guarantees this.)
+ *        .
+ *        If you choose option 1, <tt>dstSizes[i]</tt> should be set to
+ *        the size of your pre-allocated buffer.  In any case, unless you have
+ *        set #TJFLAG_NOREALLOC, you should always check <tt>dstBufs[i]</tt>
+ *        upon return from this function, as it may have changed.
+ * @param dstSizes pointer to an array of n unsigned long variables which will
+ *        receive the actual sizes (in bytes) of each transformed JPEG image.
+ *        If <tt>dstBufs[i]</tt> points to a pre-allocated buffer, then
+ *        <tt>dstSizes[i]</tt> should be set to the size of the buffer.  Upon
+ *        return, <tt>dstSizes[i]</tt> will contain the size of the JPEG image
+ *        (in bytes.)
+ * @param transforms pointer to an array of n tjtransform structures, each of
+ *        which specifies the transform parameters and/or cropping region for
+ *        the corresponding transformed output image.
+ * @param flags the bitwise OR of one or more of the @ref TJFLAG_BOTTOMUP
+ *        "flags".
+ *
+ * @return 0 if successful, or -1 if an error occurred (see #tjGetErrorStr().)
+ */
+DLLEXPORT int DLLCALL tjTransform(tjhandle handle, unsigned char *jpegBuf,
+  unsigned long jpegSize, int n, unsigned char **dstBufs,
+  unsigned long *dstSizes, tjtransform *transforms, int flags);
+
+
+/**
+ * Destroy a TurboJPEG compressor, decompressor, or transformer instance.
+ *
+ * @param handle a handle to a TurboJPEG compressor, decompressor or
+ *        transformer instance
+ *
+ * @return 0 if successful, or -1 if an error occurred (see #tjGetErrorStr().)
+ */
+DLLEXPORT int DLLCALL tjDestroy(tjhandle handle);
+
+
+/**
+ * Allocate an image buffer for use with TurboJPEG.  You should always use
+ * this function to allocate the JPEG destination buffer(s) for #tjCompress2()
+ * and #tjTransform() unless you are disabling automatic buffer
+ * (re)allocation (by setting #TJFLAG_NOREALLOC.)
+ *
+ * @param bytes the number of bytes to allocate
+ * 
+ * @return a pointer to a newly-allocated buffer with the specified number of
+ *         bytes
+ *
+ * @sa tjFree()
+ */
+DLLEXPORT unsigned char* DLLCALL tjAlloc(int bytes);
+
+
+/**
+ * Free an image buffer previously allocated by TurboJPEG.  You should always
+ * use this function to free JPEG destination buffer(s) that were automatically
+ * (re)allocated by #tjCompress2() or #tjTransform() or that were manually
+ * allocated using #tjAlloc().
+ *
+ * @param buffer address of the buffer to free
+ *
+ * @sa tjAlloc()
+ */
+DLLEXPORT void DLLCALL tjFree(unsigned char *buffer);
+
+
+/**
+ * Returns a descriptive error message explaining why the last command failed.
+ *
+ * @return a descriptive error message explaining why the last command failed.
+ */
 DLLEXPORT char* DLLCALL tjGetErrorStr(void);
 
+
+/* Backward compatibility functions and macros (nothing to see here) */
+#define NUMSUBOPT TJ_NUMSAMP
+#define TJ_444 TJSAMP_444
+#define TJ_422 TJSAMP_422
+#define TJ_420 TJSAMP_420
+#define TJ_411 TJSAMP_420
+#define TJ_GRAYSCALE TJSAMP_GRAY
+
+#define TJ_BGR 1
+#define TJ_BOTTOMUP TJFLAG_BOTTOMUP
+#define TJ_FORCEMMX TJFLAG_FORCEMMX
+#define TJ_FORCESSE TJFLAG_FORCESSE
+#define TJ_FORCESSE2 TJFLAG_FORCESSE2
+#define TJ_ALPHAFIRST 64
+#define TJ_FORCESSE3 TJFLAG_FORCESSE3
+#define TJ_FASTUPSAMPLE TJFLAG_FASTUPSAMPLE
+#define TJ_YUV 512
+
+DLLEXPORT unsigned long DLLCALL TJBUFSIZE(int width, int height);
+
+DLLEXPORT unsigned long DLLCALL TJBUFSIZEYUV(int width, int height,
+  int jpegSubsamp);
+
+DLLEXPORT int DLLCALL tjCompress(tjhandle handle, unsigned char *srcBuf,
+  int width, int pitch, int height, int pixelSize, unsigned char *dstBuf,
+  unsigned long *compressedSize, int jpegSubsamp, int jpegQual, int flags);
+
+DLLEXPORT int DLLCALL tjEncodeYUV(tjhandle handle,
+  unsigned char *srcBuf, int width, int pitch, int height, int pixelSize,
+  unsigned char *dstBuf, int subsamp, int flags);
+
+DLLEXPORT int DLLCALL tjDecompressHeader(tjhandle handle,
+  unsigned char *jpegBuf, unsigned long jpegSize, int *width, int *height);
+
+DLLEXPORT int DLLCALL tjDecompress(tjhandle handle,
+  unsigned char *jpegBuf, unsigned long jpegSize, unsigned char *dstBuf,
+  int width, int pitch, int height, int pixelSize, int flags);
+
+
+/**
+ * @}
+ */
+
 #ifdef __cplusplus
 }
 #endif
+
+#endif