Hash :
be96fa0a
Author :
Date :
2023-12-14T13:18:20
Doc: Lossless JPEG clarifications - Clarify that lossless JPEG is slower than and doesn't compress as well as lossy JPEG. (That should be obvious, because "lossy" literally means that data is thrown away.) - Re-generate TurboJPEG C API documentation using Doxygen 1.9.8. - Clarify that setting the data_precision field in jpeg_compress_struct to 16 requires lossless mode. - Explain what the predictor selection value actually does. (Refer to Recommendation ITU-T T.81 (1992) | ISO/IEC 10918-1:1994, Section H.1.2.1.)
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/*
* Copyright (C)2011-2013, 2017-2018, 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
* 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.
*/
package org.libjpegturbo.turbojpeg;
import java.awt.Rectangle;
/**
* TurboJPEG utility class (cannot be instantiated)
*/
public final class TJ {
private TJ() {}
/**
* The number of chrominance subsampling options
*/
public static final int NUMSAMP = 7;
/**
* 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.
*/
public static final int SAMP_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.
*/
public static final int SAMP_422 = 1;
/**
* 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.
*/
public static final int SAMP_420 = 2;
/**
* Grayscale. The JPEG or YUV image will contain no chrominance components.
*/
public static final int SAMP_GRAY = 3;
/**
* 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.
* Note that 4:4:0 subsampling is not fully accelerated in libjpeg-turbo.
*/
public static final int SAMP_440 = 4;
/**
* 4:1:1 chrominance subsampling. The JPEG or YUV image will contain one
* chrominance component for every 4x1 block of pixels in the source image.
* JPEG images compressed with 4:1:1 subsampling will be almost exactly the
* same size as those compressed with 4:2:0 subsampling, and in the
* aggregate, both subsampling methods produce approximately the same
* perceptual quality. However, 4:1:1 is better able to reproduce sharp
* horizontal features. Note that 4:1:1 subsampling is not fully accelerated
* in libjpeg-turbo.
*/
public static final int SAMP_411 = 5;
/**
* 4:4:1 chrominance subsampling. The JPEG or YUV image will contain one
* chrominance component for every 1x4 block of pixels in the source image.
* JPEG images compressed with 4:4:1 subsampling will be almost exactly the
* same size as those compressed with 4:2:0 subsampling, and in the
* aggregate, both subsampling methods produce approximately the same
* perceptual quality. However, 4:4:1 is better able to reproduce sharp
* vertical features. Note that 4:4:1 subsampling is not fully accelerated
* in libjpeg-turbo.
*/
public static final int SAMP_441 = 6;
/**
* Unknown subsampling. The JPEG image uses an unusual type of chrominance
* subsampling. Such images can be decompressed into packed-pixel images,
* but they cannot be
* <ul>
* <li> decompressed into planar YUV images,
* <li> losslessly transformed if {@link TJTransform#OPT_CROP} is specified,
* or
* <li> partially decompressed using a cropping region.
* </ul>
*/
public static final int SAMP_UNKNOWN = -1;
/**
* Returns the MCU block width for the given level of chrominance
* subsampling.
*
* @param subsamp the level of chrominance subsampling (one of
* {@link #SAMP_444 SAMP_*})
*
* @return the MCU block width for the given level of chrominance
* subsampling.
*/
public static int getMCUWidth(int subsamp) {
checkSubsampling(subsamp);
return MCU_WIDTH[subsamp];
}
private static final int[] MCU_WIDTH = {
8, 16, 16, 8, 8, 32, 8
};
/**
* Returns the MCU block height for the given level of chrominance
* subsampling.
*
* @param subsamp the level of chrominance subsampling (one of
* {@link #SAMP_444 SAMP_*})
*
* @return the MCU block height for the given level of chrominance
* subsampling.
*/
public static int getMCUHeight(int subsamp) {
checkSubsampling(subsamp);
return MCU_HEIGHT[subsamp];
}
private static final int[] MCU_HEIGHT = {
8, 8, 16, 8, 16, 8, 32
};
/**
* The number of pixel formats
*/
public static final int NUMPF = 12;
/**
* RGB pixel format. The red, green, and blue components in the image are
* stored in 3-sample pixels in the order R, G, B from lowest to highest
* memory address within each pixel.
*/
public static final int PF_RGB = 0;
/**
* BGR pixel format. The red, green, and blue components in the image are
* stored in 3-sample pixels in the order B, G, R from lowest to highest
* memory address within each pixel.
*/
public static final int PF_BGR = 1;
/**
* RGBX pixel format. The red, green, and blue components in the image are
* stored in 4-sample pixels in the order R, G, B from lowest to highest
* memory address within each pixel. The X component is ignored when
* compressing and undefined when decompressing.
*/
public static final int PF_RGBX = 2;
/**
* BGRX pixel format. The red, green, and blue components in the image are
* stored in 4-sample pixels in the order B, G, R from lowest to highest
* memory address within each pixel. The X component is ignored when
* compressing and undefined when decompressing.
*/
public static final int PF_BGRX = 3;
/**
* XBGR pixel format. The red, green, and blue components in the image are
* stored in 4-sample pixels in the order R, G, B from highest to lowest
* memory address within each pixel. The X component is ignored when
* compressing and undefined when decompressing.
*/
public static final int PF_XBGR = 4;
/**
* XRGB pixel format. The red, green, and blue components in the image are
* stored in 4-sample pixels in the order B, G, R from highest to lowest
* memory address within each pixel. The X component is ignored when
* compressing and undefined when decompressing.
*/
public static final int PF_XRGB = 5;
/**
* Grayscale pixel format. Each 1-sample pixel represents a luminance
* (brightness) level from 0 to the maximum sample value (255 for 8-bit
* samples, 4095 for 12-bit samples, and 65535 for 16-bit samples.)
*/
public static final int PF_GRAY = 6;
/**
* RGBA pixel format. This is the same as {@link #PF_RGBX}, except that when
* decompressing, the X component is guaranteed to be equal to the maximum
* sample value, which can be interpreted as an opaque alpha channel.
*/
public static final int PF_RGBA = 7;
/**
* BGRA pixel format. This is the same as {@link #PF_BGRX}, except that when
* decompressing, the X component is guaranteed to be equal to the maximum
* sample value, which can be interpreted as an opaque alpha channel.
*/
public static final int PF_BGRA = 8;
/**
* ABGR pixel format. This is the same as {@link #PF_XBGR}, except that when
* decompressing, the X component is guaranteed to be equal to the maximum
* sample value, which can be interpreted as an opaque alpha channel.
*/
public static final int PF_ABGR = 9;
/**
* ARGB pixel format. This is the same as {@link #PF_XRGB}, except that when
* decompressing, the X component is guaranteed to be equal to the maximum
* sample value, which can be interpreted as an opaque alpha channel.
*/
public static final int PF_ARGB = 10;
/**
* CMYK pixel format. Unlike RGB, which is an additive color model used
* primarily for display, CMYK (Cyan/Magenta/Yellow/Key) is a subtractive
* color model used primarily for printing. In the CMYK color model, the
* value of each color component typically corresponds to an amount of cyan,
* magenta, yellow, or black ink that is applied to a white background. In
* order to convert between CMYK and RGB, it is necessary to use a color
* management system (CMS.) A CMS will attempt to map colors within the
* printer's gamut to perceptually similar colors in the display's gamut and
* vice versa, but the mapping is typically not 1:1 or reversible, nor can it
* be defined with a simple formula. Thus, such a conversion is out of scope
* for a codec library. However, the TurboJPEG API allows for compressing
* packed-pixel CMYK images into YCCK JPEG images (see {@link #CS_YCCK}) and
* decompressing YCCK JPEG images into packed-pixel CMYK images.
*/
public static final int PF_CMYK = 11;
/**
* Returns the pixel size (in samples) for the given pixel format.
*
* @param pixelFormat the pixel format (one of {@link #PF_RGB PF_*})
*
* @return the pixel size (in samples) for the given pixel format.
*/
public static int getPixelSize(int pixelFormat) {
checkPixelFormat(pixelFormat);
return PIXEL_SIZE[pixelFormat];
}
private static final int[] PIXEL_SIZE = {
3, 3, 4, 4, 4, 4, 1, 4, 4, 4, 4, 4
};
/**
* For the given pixel format, returns the number of samples that the red
* component is offset from the start of the pixel. For instance, if an
* 8-bit-per-sample pixel of format <code>TJ.PF_BGRX</code> is stored in
* <code>char pixel[]</code>, then the red component will be
* <code>pixel[TJ.getRedOffset(TJ.PF_BGRX)]</code>.
*
* @param pixelFormat the pixel format (one of {@link #PF_RGB PF_*})
*
* @return the red offset for the given pixel format, or -1 if the pixel
* format does not have a red component.
*/
public static int getRedOffset(int pixelFormat) {
checkPixelFormat(pixelFormat);
return RED_OFFSET[pixelFormat];
}
private static final int[] RED_OFFSET = {
0, 2, 0, 2, 3, 1, -1, 0, 2, 3, 1, -1
};
/**
* For the given pixel format, returns the number of samples that the green
* component is offset from the start of the pixel. For instance, if an
* 8-bit-per-sample pixel of format <code>TJ.PF_BGRX</code> is stored in
* <code>char pixel[]</code>, then the green component will be
* <code>pixel[TJ.getGreenOffset(TJ.PF_BGRX)]</code>.
*
* @param pixelFormat the pixel format (one of {@link #PF_RGB PF_*})
*
* @return the green offset for the given pixel format, or -1 if the pixel
* format does not have a green component.
*/
public static int getGreenOffset(int pixelFormat) {
checkPixelFormat(pixelFormat);
return GREEN_OFFSET[pixelFormat];
}
private static final int[] GREEN_OFFSET = {
1, 1, 1, 1, 2, 2, -1, 1, 1, 2, 2, -1
};
/**
* For the given pixel format, returns the number of samples that the blue
* component is offset from the start of the pixel. For instance, if an
* 8-bit-per-sample pixel of format <code>TJ.PF_BGRX</code> is stored in
* <code>char pixel[]</code>, then the blue component will be
* <code>pixel[TJ.getBlueOffset(TJ.PF_BGRX)]</code>.
*
* @param pixelFormat the pixel format (one of {@link #PF_RGB PF_*})
*
* @return the blue offset for the given pixel format, or -1 if the pixel
* format does not have a blue component.
*/
public static int getBlueOffset(int pixelFormat) {
checkPixelFormat(pixelFormat);
return BLUE_OFFSET[pixelFormat];
}
private static final int[] BLUE_OFFSET = {
2, 0, 2, 0, 1, 3, -1, 2, 0, 1, 3, -1
};
/**
* For the given pixel format, returns the number of samples that the alpha
* component is offset from the start of the pixel. For instance, if an
* 8-bit-per-sample pixel of format <code>TJ.PF_BGRA</code> is stored in
* <code>char pixel[]</code>, then the alpha component will be
* <code>pixel[TJ.getAlphaOffset(TJ.PF_BGRA)]</code>.
*
* @param pixelFormat the pixel format (one of {@link #PF_RGB PF_*})
*
* @return the alpha offset for the given pixel format, or -1 if the pixel
* format does not have a alpha component.
*/
public static int getAlphaOffset(int pixelFormat) {
checkPixelFormat(pixelFormat);
return ALPHA_OFFSET[pixelFormat];
}
private static final int[] ALPHA_OFFSET = {
-1, -1, -1, -1, -1, -1, -1, 3, 3, 0, 0, -1
};
/**
* The number of JPEG colorspaces
*/
public static final int NUMCS = 5;
/**
* RGB colorspace. When compressing the JPEG image, the R, G, and B
* components in the source image are reordered into image planes, but no
* colorspace conversion or subsampling is performed. RGB JPEG images can be
* compressed from and decompressed to packed-pixel images with any of the
* extended RGB or grayscale pixel formats, but they cannot be compressed
* from or decompressed to planar YUV images.
*/
public static final int CS_RGB = 0;
/**
* YCbCr colorspace. YCbCr is not an absolute colorspace but rather a
* mathematical transformation of RGB designed solely for storage and
* transmission. YCbCr images must be converted to RGB before they can
* actually be displayed. In the YCbCr colorspace, the Y (luminance)
* component represents the black & white portion of the original image,
* and the Cb and Cr (chrominance) components represent the color portion of
* the original image. Originally, the analog equivalent of this
* transformation allowed the same signal to drive both black & white and
* color televisions, but JPEG images use YCbCr primarily because it allows
* the color data to be optionally subsampled for the purposes of reducing
* network or disk usage. YCbCr is the most common JPEG colorspace, and
* YCbCr JPEG images can be compressed from and decompressed to packed-pixel
* images with any of the extended RGB or grayscale pixel formats. YCbCr
* JPEG images can also be compressed from and decompressed to planar YUV
* images.
*/
@SuppressWarnings("checkstyle:ConstantName")
public static final int CS_YCbCr = 1;
/**
* Grayscale colorspace. The JPEG image retains only the luminance data (Y
* component), and any color data from the source image is discarded.
* Grayscale JPEG images can be compressed from and decompressed to
* packed-pixel images with any of the extended RGB or grayscale pixel
* formats, or they can be compressed from and decompressed to planar YUV
* images.
*/
public static final int CS_GRAY = 2;
/**
* CMYK colorspace. When compressing the JPEG image, the C, M, Y, and K
* components in the source image are reordered into image planes, but no
* colorspace conversion or subsampling is performed. CMYK JPEG images can
* only be compressed from and decompressed to packed-pixel images with the
* CMYK pixel format.
*/
public static final int CS_CMYK = 3;
/**
* YCCK colorspace. YCCK (AKA "YCbCrK") is not an absolute colorspace but
* rather a mathematical transformation of CMYK designed solely for storage
* and transmission. It is to CMYK as YCbCr is to RGB. CMYK pixels can be
* reversibly transformed into YCCK, and as with YCbCr, the chrominance
* components in the YCCK pixels can be subsampled without incurring major
* perceptual loss. YCCK JPEG images can only be compressed from and
* decompressed to packed-pixel images with the CMYK pixel format.
*/
public static final int CS_YCCK = 4;
/**
* Error handling behavior
*
* <p><b>Value</b>
* <ul>
* <li> <code>0</code> <i>[default]</i> Allow the current
* compression/decompression/transform operation to complete unless a fatal
* error is encountered.
* <li> <code>1</code> Immediately discontinue the current
* compression/decompression/transform operation if a warning (non-fatal
* error) occurs.
* </ul>
*/
public static final int PARAM_STOPONWARNING = 0;
/**
* Row order in packed-pixel source/destination images
*
* <p><b>Value</b>
* <ul>
* <li> <code>0</code> <i>[default]</i> top-down (X11) order
* <li> <code>1</code> bottom-up (Windows, OpenGL) order
* </ul>
*/
public static final int PARAM_BOTTOMUP = 1;
/**
* Perceptual quality of lossy JPEG images [compression only]
*
* <p><b>Value</b>
* <ul>
* <li> <code>1</code>-<code>100</code> (<code>1</code> = worst quality but
* best compression, <code>100</code> = best quality but worst compression)
* <i>[no default; must be explicitly specified]</i>
* </ul>
*/
public static final int PARAM_QUALITY = 3;
/**
* Chrominance subsampling level
*
* <p>The JPEG or YUV image uses (decompression, decoding) or will use (lossy
* compression, encoding) the specified level of chrominance subsampling.
*
* <p>When pixels are converted from RGB to YCbCr (see {@link #CS_YCbCr}) or
* from CMYK to YCCK (see {@link #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".
*
* <p><b>Value</b>
* <ul>
* <li> One of {@link TJ#SAMP_444 TJ.SAMP_*} <i>[no default; must be
* explicitly specified for lossy compression, encoding, and decoding]</i>
* </ul>
*/
public static final int PARAM_SUBSAMP = 4;
/**
* JPEG width (in pixels) [decompression only, read-only]
*/
public static final int PARAM_JPEGWIDTH = 5;
/**
* JPEG height (in pixels) [decompression only, read-only]
*/
public static final int PARAM_JPEGHEIGHT = 6;
/**
* JPEG data precision (bits per sample) [decompression only, read-only]
*
* <p>The JPEG image uses the specified number of bits per sample.
*
* <p><b>Value</b>
* <ul>
* <li> <code>8</code>, <code>12</code>, or <code>16</code>
* </ul>
*
* <p>12-bit data precision implies {@link #PARAM_OPTIMIZE} unless
* {@link #PARAM_ARITHMETIC} is set.
*/
public static final int PARAM_PRECISION = 7;
/**
* JPEG colorspace
*
* <p>The JPEG image uses (decompression) or will use (lossy compression) the
* specified colorspace.
*
* <p><b>Value</b>
* <ul>
* <li> One of {@link TJ#CS_RGB TJ.CS_*} <i>[default for lossy compression:
* automatically selected based on the subsampling level and pixel
* format]</i>
* </ul>
*/
public static final int PARAM_COLORSPACE = 8;
/**
* Chrominance upsampling algorithm [lossy decompression only]
*
* <p><b>Value</b>
* <ul>
* <li> <code>0</code> <i>[default]</i> Use smooth upsampling when
* decompressing a JPEG image that was compressed using chrominance
* subsampling. This creates a smooth transition between neighboring
* chrominance components in order to reduce upsampling artifacts in the
* decompressed image.
* <li> <code>1</code> Use the fastest chrominance upsampling algorithm
* available, which may combine upsampling with color conversion.
* </ul>
*/
public static final int PARAM_FASTUPSAMPLE = 9;
/**
* DCT/IDCT algorithm [lossy compression and decompression]
*
* <p><b>Value</b>
* <ul>
* <li> <code>0</code> <i>[default]</i> Use the most accurate DCT/IDCT
* algorithm available.
* <li> <code>1</code> Use the fastest DCT/IDCT algorithm available.
* </ul>
*
* <p>This parameter is provided mainly for backward compatibility with
* libjpeg, which historically implemented several different DCT/IDCT
* algorithms because of performance limitations with 1990s CPUs. In the
* libjpeg-turbo implementation of the TurboJPEG API:
*
* <ul>
* <li> The "fast" and "accurate" DCT/IDCT algorithms perform similarly on
* modern x86/x86-64 CPUs that support AVX2 instructions.
* <li> The "fast" algorithm is generally only about 5-15% faster than the
* "accurate" algorithm on other types of CPUs.
* <li> The difference in accuracy between the "fast" and "accurate"
* algorithms is the most pronounced at JPEG quality levels above 90 and
* tends to be more pronounced with decompression than with compression.
* <li> The "fast" algorithm degrades and is not fully accelerated for JPEG
* quality levels above 97, so it will be slower than the "accurate"
* algorithm.
* </ul>
*/
public static final int PARAM_FASTDCT = 10;
/**
* Optimized baseline entropy coding [lossy compression only]
*
* <p><b>Value</b>
* <ul>
* <li> <code>0</code> <i>[default]</i> The JPEG image will use the default
* Huffman tables.
* <li> <code>1</code> Optimal Huffman tables will be computed for the JPEG
* image. For lossless transformation, this can also be specified using
* {@link TJTransform#OPT_OPTIMIZE}.
* </ul>
*
* <p>Optimized baseline entropy coding will improve compression slightly
* (generally 5% or less), but it will reduce compression performance
* considerably.
*/
public static final int PARAM_OPTIMIZE = 11;
/**
* Progressive entropy coding
*
* <p><b>Value</b>
* <ul>
* <li> <code>0</code> <i>[default for compression, lossless
* transformation]</i> The lossy JPEG image uses (decompression) or will use
* (compression, lossless transformation) baseline entropy coding.
* <li> <code>1</code> The lossy JPEG image uses (decompression) or will use
* (compression, lossless transformation) progressive entropy coding. For
* lossless transformation, this can also be specified using
* {@link TJTransform#OPT_PROGRESSIVE}.
* </ul>
*
* <p>Progressive entropy coding will generally improve compression relative
* to baseline entropy coding, but it will reduce compression and
* decompression performance considerably. Can be combined with
* {@link #PARAM_ARITHMETIC}. Implies {@link #PARAM_OPTIMIZE} unless
* {@link #PARAM_ARITHMETIC} is also set.
*/
public static final int PARAM_PROGRESSIVE = 12;
/**
* Progressive JPEG scan limit for lossy JPEG images [decompression, lossless
* transformation]
*
* <p>Setting this parameter will cause the decompression and transform
* operations to throw an error if the number of scans in a progressive JPEG
* image exceeds the specified limit. The primary purpose of this is to
* allow security-critical applications to guard against an exploit of the
* progressive JPEG format described in
* <a href="https://libjpeg-turbo.org/pmwiki/uploads/About/TwoIssueswiththeJPEGStandard.pdf" target="_blank">this report</a>.
*
* <p><b>Value</b>
* <ul>
* <li> maximum number of progressive JPEG scans that the decompression and
* transform operations will process <i>[default: <code>0</code> (no
* limit)]</i>
* </ul>
*
* @see #PARAM_PROGRESSIVE
*/
public static final int PARAM_SCANLIMIT = 13;
/**
* Arithmetic entropy coding
*
* <p><b>Value</b>
* <ul>
* <li> <code>0</code> <i>[default for compression, lossless
* transformation]</i> The lossy JPEG image uses (decompression) or will use
* (compression, lossless transformation) Huffman entropy coding.
* <li> <code>1</code> The lossy JPEG image uses (decompression) or will use
* (compression, lossless transformation) arithmetic entropy coding. For
* lossless transformation, this can also be specified using
* {@link TJTransform#OPT_ARITHMETIC}.
* </ul>
*
* <p>Arithmetic entropy coding will generally improve compression relative
* to Huffman entropy coding, but it will reduce compression and
* decompression performance considerably. Can be combined with
* {@link #PARAM_PROGRESSIVE}.
*/
public static final int PARAM_ARITHMETIC = 14;
/**
* Lossless JPEG
*
* <p><b>Value</b>
* <ul>
* <li> <code>0</code> <i>[default for compression]</i> The JPEG image is
* (decompression) or will be (compression) lossy/DCT-based.
* <li> <code>1</code> The JPEG image is (decompression) or will be
* (compression) lossless/predictive.
* </ul>
*
* <p>In most cases, compressing and decompressing lossless JPEG images is
* considerably slower than compressing and decompressing lossy JPEG images,
* and lossless JPEG images are much larger than lossy JPEG images. Thus,
* lossless JPEG images are typically used only for applications that require
* mathematically lossless compression. Also note that the following
* features are not available with lossless JPEG images:
* <ul>
* <li> Colorspace conversion (lossless JPEG images always use
* {@link #CS_RGB}, {@link #CS_GRAY}, or {@link #CS_CMYK}, depending on the
* pixel format of the source image)
* <li> Chrominance subsampling (lossless JPEG images always use
* {@link #SAMP_444})
* <li> JPEG quality selection
* <li> DCT/IDCT algorithm selection
* <li> Progressive entropy coding
* <li> Arithmetic entropy coding
* <li> Compression from/decompression to planar YUV images
* <li> Decompression scaling
* <li> Lossless transformation
* </ul>
*
* @see #PARAM_LOSSLESSPSV
* @see #PARAM_LOSSLESSPT
*/
public static final int PARAM_LOSSLESS = 15;
/**
* Lossless JPEG predictor selection value (PSV)
*
* <p><b>Value</b>
* <ul>
* <li> <code>1</code>-<code>7</code> <i>[default for compression:
* <code>1</code>]</i>
* </ul>
*
* <p>Lossless JPEG compression shares no algorithms with lossy JPEG
* compression. Instead, it uses differential pulse-code modulation (DPCM),
* an algorithm whereby each sample is encoded as the difference between the
* sample's value and a "predictor", which is based on the values of
* neighboring samples. If Ra is the sample immediately to the left of the
* current sample, Rb is the sample immediately above the current sample, and
* Rc is the sample diagonally to the left and above the current sample, then
* the relationship between the predictor selection value and the predictor
* is as follows:
*
* <table border=1>
* <caption></caption>
* <tr> <th>PSV</th> <th>Predictor</th> </tr>
* <tr> <td>1</td> <td>Ra</td> </tr>
* <tr> <td>2</td> <td>Rb</td> </tr>
* <tr> <td>3</td> <td>Rc</td> </tr>
* <tr> <td>4</td> <td>Ra + Rb – Rc</td> </tr>
* <tr> <td>5</td> <td>Ra + (Rb – Rc) / 2</td> </tr>
* <tr> <td>6</td> <td>Rb + (Ra – Rc) / 2</td> </tr>
* <tr> <td>7</td> <td>(Ra + Rb) / 2</td> </tr>
* </table>
*
* <p>Predictors 1-3 are 1-dimensional predictors, whereas Predictors 4-7 are
* 2-dimensional predictors. The best predictor for a particular image
* depends on the image.
*
* @see #PARAM_LOSSLESS
*/
public static final int PARAM_LOSSLESSPSV = 16;
/**
* Lossless JPEG point transform (Pt)
*
* <p><b>Value</b>
* <ul>
* <li> <code>0</code> through <i><b>precision</b> - 1</i>, where
* <b><i>precision</i></b> is the JPEG data precision in bits <i>[default for
* compression: <code>0</code>]</i>
* </ul>
*
* <p>A point transform value of <code>0</code> is necessary in order to
* generate a fully lossless JPEG image. (A non-zero point transform value
* right-shifts the input samples by the specified number of bits, which is
* effectively a form of lossy color quantization.)
*
* @see #PARAM_LOSSLESS
* @see #PARAM_PRECISION
*/
public static final int PARAM_LOSSLESSPT = 17;
/**
* JPEG restart marker interval in MCU blocks (lossy) or samples (lossless)
* [compression only]
*
* <p>The nature of entropy coding is such that a corrupt JPEG image cannot
* be decompressed beyond the point of corruption unless it contains restart
* markers. A restart marker stops and restarts the entropy coding algorithm
* so that, if a JPEG image is corrupted, decompression can resume at the
* next marker. Thus, adding more restart markers improves the fault
* tolerance of the JPEG image, but adding too many restart markers can
* adversely affect the compression ratio and performance.
*
* <p><b>Value</b>
* <ul>
* <li> the number of MCU blocks or samples between each restart marker
* <i>[default: <code>0</code> (no restart markers)]</i>
* </ul>
*
* <p> Setting this parameter to a non-zero value sets
* {@link #PARAM_RESTARTROWS} to 0.
*/
public static final int PARAM_RESTARTBLOCKS = 18;
/**
* JPEG restart marker interval in MCU rows (lossy) or sample rows (lossless)
* [compression only]
*
* <p>See {@link #PARAM_RESTARTBLOCKS} for a description of restart markers.
*
* <p><b>Value</b>
* <ul>
* <li> the number of MCU rows or sample rows between each restart marker
* <i>[default: <code>0</code> (no restart markers)]</i>
* </ul>
*
* <p>Setting this parameter to a non-zero value sets
* {@link #PARAM_RESTARTBLOCKS} to 0.
*/
public static final int PARAM_RESTARTROWS = 19;
/**
* JPEG horizontal pixel density
*
* <p><b>Value</b>
* <ul>
* <li> The JPEG image has (decompression) or will have (compression) the
* specified horizontal pixel density <i>[default for compression:
* <code>1</code>]</i>.
* </ul>
*
* <p>This value is stored in or read from the JPEG header. It does not
* affect the contents of the JPEG image.
*
* @see #PARAM_DENSITYUNITS
*/
public static final int PARAM_XDENSITY = 20;
/**
* JPEG vertical pixel density
*
* <p><b>Value</b>
* <ul>
* <li> The JPEG image has (decompression) or will have (compression) the
* specified vertical pixel density <i>[default for compression:
* <code>1</code>]</i>.
* </ul>
*
* <p>This value is stored in or read from the JPEG header. It does not
* affect the contents of the JPEG image.
*
* @see #PARAM_DENSITYUNITS
*/
public static final int PARAM_YDENSITY = 21;
/**
* JPEG pixel density units
*
* <p><b>Value</b>
* <ul>
* <li> <code>0</code> <i>[default for compression]</i> The pixel density of
* the JPEG image is expressed (decompression) or will be expressed
* (compression) in unknown units.
* <li> <code>1</code> The pixel density of the JPEG image is expressed
* (decompression) or will be expressed (compression) in units of
* pixels/inch.
* <li> <code>2</code> The pixel density of the JPEG image is expressed
* (decompression) or will be expressed (compression) in units of pixels/cm.
* </ul>
*
* <p>This value is stored in or read from the JPEG header. It does not
* affect the contents of the JPEG image.
*
* @see #PARAM_XDENSITY
* @see #PARAM_YDENSITY
*/
public static final int PARAM_DENSITYUNITS = 22;
/**
* Memory limit for intermediate buffers
*
* <p><b>Value</b>
* <ul>
* <li> the maximum amount of memory (in megabytes) that will be allocated
* for intermediate buffers, which are used with progressive JPEG compression
* and decompression, optimized baseline entropy coding, lossless JPEG
* compression, and lossless transformation <i>[default: <code>0</code> (no
* limit)]</i>
* </ul>
*/
public static final int PARAM_MAXMEMORY = 23;
/**
* Image size limit [decompression, lossless transformation]
*
* <p>Setting this parameter will cause the decompression and transform
* operations to throw an error if the number of pixels in the JPEG source
* image exceeds the specified limit. This allows security-critical
* applications to guard against excessive memory consumption.
*
* <p><b>Value</b>
* <ul>
* <li> maximum number of pixels that the decompression and transform
* operations will process <i>[default: <code>0</code> (no limit)]</i>
* </ul>
*/
public static final int PARAM_MAXPIXELS = 24;
/**
* @deprecated Use {@link #PARAM_BOTTOMUP} instead.
*/
@Deprecated
public static final int FLAG_BOTTOMUP = 2;
/**
* @deprecated Use {@link #PARAM_FASTUPSAMPLE} instead.
*/
@Deprecated
public static final int FLAG_FASTUPSAMPLE = 256;
/**
* @deprecated Use {@link #PARAM_FASTDCT} instead.
*/
@Deprecated
public static final int FLAG_FASTDCT = 2048;
/**
* @deprecated Use {@link #PARAM_FASTDCT} instead.
*/
@Deprecated
public static final int FLAG_ACCURATEDCT = 4096;
/**
* @deprecated Use {@link #PARAM_STOPONWARNING} instead.
*/
@Deprecated
public static final int FLAG_STOPONWARNING = 8192;
/**
* @deprecated Use {@link #PARAM_PROGRESSIVE} instead.
*/
@Deprecated
public static final int FLAG_PROGRESSIVE = 16384;
/**
* @deprecated Use {@link #PARAM_SCANLIMIT} instead.
*/
@Deprecated
public static final int FLAG_LIMITSCANS = 32768;
/**
* The number of error codes
*/
public static final int NUMERR = 2;
/**
* The error was non-fatal and recoverable, but the destination image may
* still be corrupt.
* <p>
* NOTE: due to the design of the TurboJPEG Java API, only certain methods
* (specifically, {@link TJDecompressor TJDecompressor.decompress*()} methods
* with a void return type) will complete and leave the destination image in
* a fully recoverable state after a non-fatal error occurs.
*/
public static final int ERR_WARNING = 0;
/**
* The error was fatal and non-recoverable.
*/
public static final int ERR_FATAL = 1;
/**
* Returns the maximum size of the buffer (in bytes) required to hold a JPEG
* image with the given width, height, and level of chrominance subsampling.
*
* @param width the width (in pixels) of the JPEG image
*
* @param height the height (in pixels) of the JPEG image
*
* @param jpegSubsamp the level of chrominance subsampling to be used when
* generating the JPEG image (one of {@link #SAMP_444 TJ.SAMP_*}.)
* {@link #SAMP_UNKNOWN} is treated like {@link #SAMP_444}, since a buffer
* large enough to hold a JPEG image with no subsampling should also be large
* enough to hold a JPEG image with an arbitrary level of subsampling. Note
* that lossless JPEG images always use {@link #SAMP_444}.
*
* @return the maximum size of the buffer (in bytes) required to hold a JPEG
* image with the given width, height, and level of chrominance subsampling.
*/
public static native int bufSize(int width, int height, int jpegSubsamp);
/**
* Returns the size of the buffer (in bytes) required to hold a unified
* planar YUV image with the given width, height, and level of chrominance
* subsampling.
*
* @param width the width (in pixels) of the YUV image
*
* @param align row alignment (in bytes) of the YUV image (must be a power of
* 2.) Setting this parameter to n specifies that each row in each plane of
* the YUV image will be padded to the nearest multiple of n bytes
* (1 = unpadded.)
*
* @param height the height (in pixels) of the YUV image
*
* @param subsamp the level of chrominance subsampling used in the YUV
* image (one of {@link #SAMP_444 TJ.SAMP_*})
*
* @return the size of the buffer (in bytes) required to hold a unified
* planar YUV image with the given width, height, and level of chrominance
* subsampling.
*/
public static native int bufSizeYUV(int width, int align, int height,
int subsamp);
/**
* Returns the size of the buffer (in bytes) required to hold a YUV image
* plane with the given parameters.
*
* @param componentID ID number of the image plane (0 = Y, 1 = U/Cb,
* 2 = V/Cr)
*
* @param width width (in pixels) of the YUV image. NOTE: this is the width
* of the whole image, not the plane width.
*
* @param stride bytes per row in the image plane.
*
* @param height height (in pixels) of the YUV image. NOTE: this is the
* height of the whole image, not the plane height.
*
* @param subsamp the level of chrominance subsampling used in the YUV
* image (one of {@link #SAMP_444 TJ.SAMP_*})
*
* @return the size of the buffer (in bytes) required to hold a YUV image
* plane with the given parameters.
*/
public static native int planeSizeYUV(int componentID, int width, int stride,
int height, int subsamp);
/**
* Returns the plane width of a YUV image plane with the given parameters.
* Refer to {@link YUVImage} for a description of plane width.
*
* @param componentID ID number of the image plane (0 = Y, 1 = U/Cb,
* 2 = V/Cr)
*
* @param width width (in pixels) of the YUV image
*
* @param subsamp the level of chrominance subsampling used in the YUV image
* (one of {@link #SAMP_444 TJ.SAMP_*})
*
* @return the plane width of a YUV image plane with the given parameters.
*/
public static native int planeWidth(int componentID, int width, int subsamp);
/**
* Returns the plane height of a YUV image plane with the given parameters.
* Refer to {@link YUVImage} for a description of plane height.
*
* @param componentID ID number of the image plane (0 = Y, 1 = U/Cb,
* 2 = V/Cr)
*
* @param height height (in pixels) of the YUV image
*
* @param subsamp the level of chrominance subsampling used in the YUV image
* (one of {@link #SAMP_444 TJ.SAMP_*})
*
* @return the plane height of a YUV image plane with the given parameters.
*/
public static native int planeHeight(int componentID, int height,
int subsamp);
/**
* Returns a list of fractional scaling factors that the JPEG decompressor
* supports.
*
* @return a list of fractional scaling factors that the JPEG decompressor
* supports.
*/
public static native TJScalingFactor[] getScalingFactors();
/**
* A {@link TJScalingFactor} instance that specifies a scaling factor of 1/1
* (no scaling)
*/
public static final TJScalingFactor UNSCALED = new TJScalingFactor(1, 1);
/**
* A <code>java.awt.Rectangle</code> instance that specifies no cropping
*/
public static final Rectangle UNCROPPED = new Rectangle(0, 0, 0, 0);
static {
TJLoader.load();
}
private static void checkPixelFormat(int pixelFormat) {
if (pixelFormat < 0 || pixelFormat >= NUMPF)
throw new IllegalArgumentException("Invalid pixel format");
}
private static void checkSubsampling(int subsamp) {
if (subsamp < 0 || subsamp >= NUMSAMP)
throw new IllegalArgumentException("Invalid subsampling type");
}
}