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TurboJPEG: Numerous documentation improvements

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- Wordsmithing, formatting, and grammar tweaks

- Various clarifications and corrections, including specifying whether
  a particular buffer or image is used as a source or destination

- Accommodate/mention features that were introduced since the API
  documentation was created.

- For clarity, use "packed-pixel" to describe uncompressed
  source/destination images that are not planar YUV.

- Use "row" rather than "line" to refer to a single horizontal group of
  pixels or component values, for consistency with the libjpeg API
  documentation.  (libjpeg also uses "scanline", which is a more archaic
  term.)

- Use "alignment" rather than "padding" to refer to the number of bytes
  by which a row's width is evenly divisible.  This consistifies the
  documention of the YUV functions and tjLoadImage().  ("Padding"
  typically refers to the number of bytes added to each row, which is
  not the same thing.)

- Remove all references to "the underlying codec."  Although the
  TurboJPEG API originated as a cross-platform wrapper for the Intel
  Integrated Performance Primitives, Sun mediaLib, QuickTime, and
  libjpeg, none of those TurboJPEG implementations has been maintained
  since 2009.  Nothing would prevent someone from implementing the
  TurboJPEG API without libjpeg-turbo, but such an implementation would
  not necessarily have an "underlying codec."  (It could be fully
  self-contained.)

- Use "destination image" rather than "output image", for consistency,
  or describe the type of image that will be output.

- Avoid the term "image buffer" and instead use "byte buffer" to
  refer to buffers that will hold JPEG images, or describe the type of
  image that will be contained in the buffer.  (The Java documentation
  doesn't use "byte buffer", because the buffer arrays literally have
  "byte" in front of them, and since Java doesn't have pointers, it is
  not possible for mere mortals to store any other type of data in those
  arrays.)

- C: Use "unified" to describe YUV images stored in a single buffer, for
  consistency with the Java documentation.

- Use "planar YUV" rather than "YUV planar".  Is is our convention to
  describe images using {component layout} {colorspace/pixel format}
  {image function}, e.g. "packed-pixel RGB source image" or "planar YUV
  destination image."

- C: Document the TurboJPEG API version in which a particular function
  or macro was introduced, and reorder the backward compatibility
  function stubs in turbojpeg.h alphabetically by API version.

- C: Use Markdown rather than HTML tags, where possible, in the Doxygen
  comments.
This commit is contained in:
DRC
2023-01-06 10:29:10 -06:00
parent b03ee8b835
commit 9a146f0f23
31 changed files with 1845 additions and 1716 deletions
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135
java/org/libjpegturbo/turbojpeg/TJCompressor.java
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@@ -1,5 +1,6 @@
/*
* Copyright (C)2011-2015, 2018, 2020 D. R. Commander. All Rights Reserved.
* Copyright (C)2011-2015, 2018, 2020, 2023 D. R. Commander.
* All Rights Reserved.
* Copyright (C)2015 Viktor Szathmáry. All Rights Reserved.
*
* Redistribution and use in source and binary forms, with or without
@@ -49,7 +50,7 @@ public class TJCompressor implements Closeable {
}
/**
* Create a TurboJPEG compressor instance and associate the uncompressed
* Create a TurboJPEG compressor instance and associate the packed-pixel
* source image stored in <code>srcImage</code> with the newly created
* instance.
*
@@ -85,7 +86,7 @@ public class TJCompressor implements Closeable {
}
/**
* Create a TurboJPEG compressor instance and associate the uncompressed
* Create a TurboJPEG compressor instance and associate the packed-pixel
* source image stored in <code>srcImage</code> with the newly created
* instance.
*
@@ -110,11 +111,11 @@ public class TJCompressor implements Closeable {
}
/**
* Associate an uncompressed RGB, grayscale, or CMYK source image with this
* Associate a packed-pixel RGB, grayscale, or CMYK source image with this
* compressor instance.
*
* @param srcImage image buffer containing RGB, grayscale, or CMYK pixels to
* be compressed or encoded. This buffer is not modified.
* @param srcImage buffer containing a packed-pixel RGB, grayscale, or CMYK
* source image to be compressed or encoded. This buffer is not modified.
*
* @param x x offset (in pixels) of the region in the source image from which
* the JPEG or YUV image should be compressed/encoded
@@ -125,13 +126,13 @@ public class TJCompressor implements Closeable {
* @param width width (in pixels) of the region in the source image from
* which the JPEG or YUV image should be compressed/encoded
*
* @param pitch bytes per line of the source image. Normally, this should be
* <code>width * TJ.pixelSize(pixelFormat)</code> if the source image is
* unpadded, but you can use this parameter to, for instance, specify that
* the scanlines in the source image are padded to a 4-byte boundary or to
* compress/encode a JPEG or YUV image from a region of a larger source
* image. 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
* @param pitch bytes per row in the source image. Normally this should be
* <code>width * TJ.pixelSize(pixelFormat)</code>, if the source image is
* unpadded. However, you can use this parameter to, for instance, specify
* that the rows in the source image are padded to the nearest multiple of 4
* bytes or to compress/encode a JPEG or YUV image from a region of a larger
* source image. You can also be clever and use this parameter to skip rows,
* etc. Setting this parameter to 0 is the equivalent of setting it to
* <code>width * TJ.pixelSize(pixelFormat)</code>.
*
* @param height height (in pixels) of the region in the source image from
@@ -174,11 +175,12 @@ public class TJCompressor implements Closeable {
}
/**
* Associate an uncompressed RGB or grayscale source image with this
* Associate a packed-pixel RGB or grayscale source image with this
* compressor instance.
*
* @param srcImage a <code>BufferedImage</code> instance containing RGB or
* grayscale pixels to be compressed or encoded. This image is not modified.
* @param srcImage a <code>BufferedImage</code> instance containing a
* packed-pixel RGB or grayscale source image to be compressed or encoded.
* This image is not modified.
*
* @param x x offset (in pixels) of the region in the source image from which
* the JPEG or YUV image should be compressed/encoded
@@ -260,11 +262,10 @@ public class TJCompressor implements Closeable {
}
/**
* Associate an uncompressed YUV planar source image with this compressor
* instance.
* Associate a planar YUV source image with this compressor instance.
*
* @param srcImage YUV planar image to be compressed. This image is not
* modified.
* @param srcImage planar YUV source image to be compressed. This image is
* not modified.
*/
public void setSourceImage(YUVImage srcImage) throws TJException {
if (handle == 0) init();
@@ -281,16 +282,16 @@ public class TJCompressor implements Closeable {
* {@link TJ#CS_YCbCr}) or from CMYK to YCCK (see {@link TJ#CS_YCCK}) 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 to small changes in color.)
* This is called "chrominance subsampling".
* image with little perceptible loss of image clarity. (The human eye is
* more sensitive to small changes in brightness than to small changes in
* color.) This is called "chrominance subsampling".
* <p>
* NOTE: This method has no effect when compressing a JPEG image from a YUV
* planar source. In that case, the level of chrominance subsampling in
* the JPEG image is determined by the source. Furthermore, this method has
* no effect when encoding to a pre-allocated {@link YUVImage} instance. In
* that case, the level of chrominance subsampling is determined by the
* destination.
* NOTE: This method has no effect when compressing a JPEG image from a
* planar YUV source image. In that case, the level of chrominance
* subsampling in the JPEG image is determined by the source image.
* Furthermore, this method has no effect when encoding to a pre-allocated
* {@link YUVImage} instance. In that case, the level of chrominance
* subsampling is determined by the destination image.
*
* @param newSubsamp the level of chrominance subsampling to use in
* subsequent compress/encode oeprations (one of
@@ -315,8 +316,9 @@ public class TJCompressor implements Closeable {
}
/**
* Compress the uncompressed source image associated with this compressor
* instance and output a JPEG image to the given destination buffer.
* Compress the packed-pixel or planar YUV source image associated with this
* compressor instance and output a JPEG image to the given destination
* buffer.
*
* @param dstBuf buffer that will receive the JPEG image. Use
* {@link TJ#bufSize} to determine the maximum size for this buffer based on
@@ -366,8 +368,8 @@ public class TJCompressor implements Closeable {
}
/**
* Compress the uncompressed source image associated with this compressor
* instance and return a buffer containing a JPEG image.
* Compress the packed-pixel or planar YUV source image associated with this
* compressor instance and return a buffer containing a JPEG image.
*
* @param flags the bitwise OR of one or more of
* {@link TJ#FLAG_BOTTOMUP TJ.FLAG_*}
@@ -417,14 +419,14 @@ public class TJCompressor implements Closeable {
}
/**
* Encode the uncompressed source image associated with this compressor
* instance into a YUV planar image and store it in the given
* <code>YUVImage</code> instance. This method uses the accelerated color
* conversion routines in TurboJPEG's underlying codec but does not execute
* any of the other steps in the JPEG compression process. Encoding
* CMYK source images to YUV is not supported.
* Encode the packed-pixel source image associated with this compressor
* instance into a planar YUV image and store it in the given
* {@link YUVImage} instance. This method performs color conversion (which
* is accelerated in the libjpeg-turbo implementation) but does not execute
* any of the other steps in the JPEG compression process. Encoding CMYK
* source images into YUV images is not supported.
*
* @param dstImage {@link YUVImage} instance that will receive the YUV planar
* @param dstImage {@link YUVImage} instance that will receive the planar YUV
* image
*
* @param flags the bitwise OR of one or more of
@@ -469,52 +471,54 @@ public class TJCompressor implements Closeable {
}
/**
* Encode the uncompressed source image associated with this compressor
* instance into a unified YUV planar image buffer and return a
* <code>YUVImage</code> instance containing the encoded image. This method
* uses the accelerated color conversion routines in TurboJPEG's underlying
* codec but does not execute any of the other steps in the JPEG compression
* process. Encoding CMYK source images to YUV is not supported.
* Encode the packed-pixel source image associated with this compressor
* instance into a unified planar YUV image and return a {@link YUVImage}
* instance containing the encoded image. This method performs color
* conversion (which is accelerated in the libjpeg-turbo implementation) but
* does not execute any of the other steps in the JPEG compression process.
* Encoding CMYK source images into YUV images is not supported.
*
* @param pad the width of each line in each plane of the YUV image will be
* padded to the nearest multiple of this number of bytes (must be a power of
* 2.)
* @param align row alignment (in bytes) of the YUV image (must be a power of
* 2.) Setting this parameter to n will cause each row in each plane of the
* YUV image to be padded to the nearest multiple of n bytes (1 = unpadded.)
*
* @param flags the bitwise OR of one or more of
* {@link TJ#FLAG_BOTTOMUP TJ.FLAG_*}
*
* @return a YUV planar image.
* @return a {@link YUVImage} instance containing the unified planar YUV
* encoded image
*/
public YUVImage encodeYUV(int pad, int flags) throws TJException {
public YUVImage encodeYUV(int align, int flags) throws TJException {
checkSourceImage();
checkSubsampling();
if (pad < 1 || ((pad & (pad - 1)) != 0))
if (align < 1 || ((align & (align - 1)) != 0))
throw new IllegalStateException("Invalid argument in encodeYUV()");
YUVImage dstYUVImage = new YUVImage(srcWidth, pad, srcHeight, subsamp);
YUVImage dstYUVImage = new YUVImage(srcWidth, align, srcHeight, subsamp);
encodeYUV(dstYUVImage, flags);
return dstYUVImage;
}
/**
* Encode the uncompressed source image associated with this compressor
* Encode the packed-pixel source image associated with this compressor
* instance into separate Y, U (Cb), and V (Cr) image planes and return a
* <code>YUVImage</code> instance containing the encoded image planes. This
* method uses the accelerated color conversion routines in TurboJPEG's
* underlying codec but does not execute any of the other steps in the JPEG
* compression process. Encoding CMYK source images to YUV is not supported.
* {@link YUVImage} instance containing the encoded image planes. This
* method performs color conversion (which is accelerated in the
* libjpeg-turbo implementation) but does not execute any of the other steps
* in the JPEG compression process. Encoding CMYK source images into YUV
* images is not supported.
*
* @param strides an array of integers, each specifying the number of bytes
* per line in the corresponding plane of the output image. Setting the
* stride for any plane to 0 is the same as setting it to the component width
* of the plane. If <code>strides</code> is null, then the strides for all
* planes will be set to their respective component widths. You can adjust
* the strides in order to add an arbitrary amount of line padding to each
* plane.
* per row in the corresponding plane of the YUV source image. Setting the
* stride for any plane to 0 is the same as setting it to the plane width
* (see {@link YUVImage}.) If <code>strides</code> is null, then the strides
* for all planes will be set to their respective plane widths. You can
* adjust the strides in order to add an arbitrary amount of row padding to
* each plane.
*
* @param flags the bitwise OR of one or more of
* {@link TJ#FLAG_BOTTOMUP TJ.FLAG_*}
*
* @return a YUV planar image.
* @return a {@link YUVImage} instance containing the encoded image planes
*/
public YUVImage encodeYUV(int[] strides, int flags) throws TJException {
checkSourceImage();
@@ -679,6 +683,5 @@ public class TJCompressor implements Closeable {
private int subsamp = -1;
private int jpegQuality = -1;
private int compressedSize = 0;
private int yuvPad = 4;
private ByteOrder byteOrder = null;
}