org.libjpegturbo.turbojpeg
Class TJ

java.lang.Object
  extended by org.libjpegturbo.turbojpeg.TJ

public final class TJ
extends java.lang.Object

TurboJPEG utility class (cannot be instantiated)


Field Summary
static int CS_CMYK
          CMYK colorspace.
static int CS_GRAY
          Grayscale colorspace.
static int CS_RGB
          RGB colorspace.
static int CS_YCbCr
          YCbCr colorspace.
static int CS_YCCK
          YCCK colorspace.
static int FLAG_ACCURATEDCT
          Use the most accurate DCT/IDCT algorithm available in the underlying codec.
static int FLAG_BOTTOMUP
          The uncompressed source/destination image is stored in bottom-up (Windows, OpenGL) order, not top-down (X11) order.
static int FLAG_FASTDCT
          Use the fastest DCT/IDCT algorithm available in the underlying codec.
static int FLAG_FASTUPSAMPLE
          When decompressing an image that was compressed using chrominance subsampling, use the fastest chrominance upsampling algorithm available in the underlying codec.
static int FLAG_FORCEMMX
          Deprecated. 
static int FLAG_FORCESSE
          Deprecated. 
static int FLAG_FORCESSE2
          Deprecated. 
static int FLAG_FORCESSE3
          Deprecated. 
static int NUMCS
          The number of JPEG colorspaces
static int NUMPF
          The number of pixel formats
static int NUMSAMP
          The number of chrominance subsampling options
static int PF_ABGR
          ABGR pixel format.
static int PF_ARGB
          ARGB pixel format.
static int PF_BGR
          BGR pixel format.
static int PF_BGRA
          BGRA pixel format.
static int PF_BGRX
          BGRX pixel format.
static int PF_CMYK
          CMYK pixel format.
static int PF_GRAY
          Grayscale pixel format.
static int PF_RGB
          RGB pixel format.
static int PF_RGBA
          RGBA pixel format.
static int PF_RGBX
          RGBX pixel format.
static int PF_XBGR
          XBGR pixel format.
static int PF_XRGB
          XRGB pixel format.
static int SAMP_411
          4:1:1 chrominance subsampling.
static int SAMP_420
          4:2:0 chrominance subsampling.
static int SAMP_422
          4:2:2 chrominance subsampling.
static int SAMP_440
          4:4:0 chrominance subsampling.
static int SAMP_444
          4:4:4 chrominance subsampling (no chrominance subsampling).
static int SAMP_GRAY
          Grayscale.
 
Constructor Summary
TJ()
           
 
Method Summary
static int bufSize(int width, int height, int jpegSubsamp)
          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.
static int bufSizeYUV(int width, int height, int subsamp)
          Deprecated. Use bufSizeYUV(int, int, int, int) instead.
static int bufSizeYUV(int width, int pad, int height, int subsamp)
          Returns the size of the buffer (in bytes) required to hold a YUV planar image with the given width, height, and level of chrominance subsampling.
static int getBlueOffset(int pixelFormat)
          For the given pixel format, returns the number of bytes that the blue component is offset from the start of the pixel.
static int getGreenOffset(int pixelFormat)
          For the given pixel format, returns the number of bytes that the green component is offset from the start of the pixel.
static int getMCUHeight(int subsamp)
          Returns the MCU block height for the given level of chrominance subsampling.
static int getMCUWidth(int subsamp)
          Returns the MCU block width for the given level of chrominance subsampling.
static int getPixelSize(int pixelFormat)
          Returns the pixel size (in bytes) for the given pixel format.
static int getRedOffset(int pixelFormat)
          For the given pixel format, returns the number of bytes that the red component is offset from the start of the pixel.
static TJScalingFactor[] getScalingFactors()
          Returns a list of fractional scaling factors that the JPEG decompressor in this implementation of TurboJPEG supports.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

NUMSAMP

public static final int NUMSAMP
The number of chrominance subsampling options

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Constant Field Values

SAMP_444

public static final int SAMP_444
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.

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Constant Field Values

SAMP_422

public static final int SAMP_422
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.

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Constant Field Values

SAMP_420

public static final int SAMP_420
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.

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Constant Field Values

SAMP_GRAY

public static final int SAMP_GRAY
Grayscale. The JPEG or YUV image will contain no chrominance components.

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Constant Field Values

SAMP_440

public static final int SAMP_440
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.

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Constant Field Values

SAMP_411

public static final int SAMP_411
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.

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Constant Field Values

NUMPF

public static final int NUMPF
The number of pixel formats

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Constant Field Values

PF_RGB

public static final int PF_RGB
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.

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Constant Field Values

PF_BGR

public static final int PF_BGR
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.

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Constant Field Values

PF_RGBX

public static final int PF_RGBX
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. The X component is ignored when compressing and undefined when decompressing.

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Constant Field Values

PF_BGRX

public static final int PF_BGRX
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. The X component is ignored when compressing and undefined when decompressing.

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Constant Field Values

PF_XBGR

public static final int PF_XBGR
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. The X component is ignored when compressing and undefined when decompressing.

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Constant Field Values

PF_XRGB

public static final int PF_XRGB
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. The X component is ignored when compressing and undefined when decompressing.

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Constant Field Values

PF_GRAY

public static final int PF_GRAY
Grayscale pixel format. Each 1-byte pixel represents a luminance (brightness) level from 0 to 255.

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Constant Field Values

PF_RGBA

public static final int PF_RGBA
RGBA pixel format. This is the same as PF_RGBX, except that when decompressing, the X byte is guaranteed to be 0xFF, which can be interpreted as an opaque alpha channel.

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Constant Field Values

PF_BGRA

public static final int PF_BGRA
BGRA pixel format. This is the same as PF_BGRX, except that when decompressing, the X byte is guaranteed to be 0xFF, which can be interpreted as an opaque alpha channel.

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Constant Field Values

PF_ABGR

public static final int PF_ABGR
ABGR pixel format. This is the same as PF_XBGR, except that when decompressing, the X byte is guaranteed to be 0xFF, which can be interpreted as an opaque alpha channel.

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Constant Field Values

PF_ARGB

public static final int PF_ARGB
ARGB pixel format. This is the same as PF_XRGB, except that when decompressing, the X byte is guaranteed to be 0xFF, which can be interpreted as an opaque alpha channel.

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Constant Field Values

PF_CMYK

public static final int PF_CMYK
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 CMYK pixels into a YCCK JPEG image (see CS_YCCK) and decompressing YCCK JPEG images into CMYK pixels.

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Constant Field Values

NUMCS

public static final int NUMCS
The number of JPEG colorspaces

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Constant Field Values

CS_RGB

public static final int CS_RGB
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 decompressed to any of the extended RGB pixel formats or grayscale, but they cannot be decompressed to YUV images.

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Constant Field Values

CS_YCbCr

public static final int CS_YCbCr
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 bandwidth or disk space. YCbCr is the most common JPEG colorspace, and YCbCr JPEG images can be compressed from and decompressed to any of the extended RGB pixel formats or grayscale, or they can be decompressed to YUV planar images.

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Constant Field Values

CS_GRAY

public static final int CS_GRAY
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 any of the extended RGB pixel formats or grayscale, or they can be decompressed to YUV planar images.

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Constant Field Values

CS_CMYK

public static final int CS_CMYK
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 decompressed to CMYK pixels.

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Constant Field Values

CS_YCCK

public static final int CS_YCCK
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 CMYK pixels.

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Constant Field Values

FLAG_BOTTOMUP

public static final int FLAG_BOTTOMUP
The uncompressed source/destination image is stored in bottom-up (Windows, OpenGL) order, not top-down (X11) order.

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Constant Field Values

FLAG_FORCEMMX

@Deprecated
public static final int FLAG_FORCEMMX
Deprecated. 
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Constant Field Values

FLAG_FORCESSE

@Deprecated
public static final int FLAG_FORCESSE
Deprecated. 
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Constant Field Values

FLAG_FORCESSE2

@Deprecated
public static final int FLAG_FORCESSE2
Deprecated. 
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Constant Field Values

FLAG_FORCESSE3

@Deprecated
public static final int FLAG_FORCESSE3
Deprecated. 
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Constant Field Values

FLAG_FASTUPSAMPLE

public static final int FLAG_FASTUPSAMPLE
When decompressing an image that was compressed using chrominance subsampling, use the fastest chrominance upsampling algorithm available in the underlying codec. The default is to use smooth upsampling, which creates a smooth transition between neighboring chrominance components in order to reduce upsampling artifacts in the decompressed image.

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Constant Field Values

FLAG_FASTDCT

public static final int FLAG_FASTDCT
Use the fastest DCT/IDCT algorithm available in the underlying codec. The default if this flag is not specified is implementation-specific. For example, the implementation of TurboJPEG for libjpeg[-turbo] uses the fast algorithm by default when compressing, because this has been shown to have only a very slight effect on accuracy, but it uses the accurate algorithm when decompressing, because this has been shown to have a larger effect.

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Constant Field Values

FLAG_ACCURATEDCT

public static final int FLAG_ACCURATEDCT
Use the most accurate DCT/IDCT algorithm available in the underlying codec. The default if this flag is not specified is implementation-specific. For example, the implementation of TurboJPEG for libjpeg[-turbo] uses the fast algorithm by default when compressing, because this has been shown to have only a very slight effect on accuracy, but it uses the accurate algorithm when decompressing, because this has been shown to have a larger effect.

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Constant Field Values
Constructor Detail

TJ

public TJ()
Method Detail

getMCUWidth

public static int getMCUWidth(int subsamp)
                       throws java.lang.Exception
Returns the MCU block width for the given level of chrominance subsampling.

Parameters:
subsamp - the level of chrominance subsampling (one of SAMP_*)
Returns:
the MCU block width for the given level of chrominance subsampling
Throws:
java.lang.Exception

getMCUHeight

public static int getMCUHeight(int subsamp)
                        throws java.lang.Exception
Returns the MCU block height for the given level of chrominance subsampling.

Parameters:
subsamp - the level of chrominance subsampling (one of SAMP_*)
Returns:
the MCU block height for the given level of chrominance subsampling
Throws:
java.lang.Exception

getPixelSize

public static int getPixelSize(int pixelFormat)
                        throws java.lang.Exception
Returns the pixel size (in bytes) for the given pixel format.

Parameters:
pixelFormat - the pixel format (one of PF_*)
Returns:
the pixel size (in bytes) for the given pixel format
Throws:
java.lang.Exception

getRedOffset

public static int getRedOffset(int pixelFormat)
                        throws java.lang.Exception
For the given pixel format, returns the number of bytes that the red component is offset from the start of the pixel. For instance, if a pixel of format TJ.PF_BGRX is stored in char pixel[], then the red component will be pixel[TJ.getRedOffset(TJ.PF_BGRX)].

Parameters:
pixelFormat - the pixel format (one of PF_*)
Returns:
the red offset for the given pixel format
Throws:
java.lang.Exception

getGreenOffset

public static int getGreenOffset(int pixelFormat)
                          throws java.lang.Exception
For the given pixel format, returns the number of bytes that the green component is offset from the start of the pixel. For instance, if a pixel of format TJ.PF_BGRX is stored in char pixel[], then the green component will be pixel[TJ.getGreenOffset(TJ.PF_BGRX)].

Parameters:
pixelFormat - the pixel format (one of PF_*)
Returns:
the green offset for the given pixel format
Throws:
java.lang.Exception

getBlueOffset

public static int getBlueOffset(int pixelFormat)
                         throws java.lang.Exception
For the given pixel format, returns the number of bytes that the blue component is offset from the start of the pixel. For instance, if a pixel of format TJ.PF_BGRX is stored in char pixel[], then the blue component will be pixel[TJ.getBlueOffset(TJ.PF_BGRX)].

Parameters:
pixelFormat - the pixel format (one of PF_*)
Returns:
the blue offset for the given pixel format
Throws:
java.lang.Exception

bufSize

public static int bufSize(int width,
                          int height,
                          int jpegSubsamp)
                   throws java.lang.Exception
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.

Parameters:
width - the width (in pixels) of the JPEG image
height - the height (in pixels) of the JPEG image
jpegSubsamp - the level of chrominance subsampling to be used when generating the JPEG image (one of TJ.SAMP_*)
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
Throws:
java.lang.Exception

bufSizeYUV

public static int bufSizeYUV(int width,
                             int pad,
                             int height,
                             int subsamp)
                      throws java.lang.Exception
Returns the size of the buffer (in bytes) required to hold a YUV planar image with the given width, height, and level of chrominance subsampling.

Parameters:
width - the width (in pixels) of the YUV image
pad - the width of each line in each plane of the image is padded to the nearest multiple of this number of bytes (must be a power of 2.)
height - the height (in pixels) of the YUV image
subsamp - the level of chrominance subsampling used in the YUV image (one of TJ.SAMP_*)
Returns:
the size of the buffer (in bytes) required to hold a YUV planar image with the given width, height, and level of chrominance subsampling
Throws:
java.lang.Exception

bufSizeYUV

@Deprecated
public static int bufSizeYUV(int width,
                                        int height,
                                        int subsamp)
                      throws java.lang.Exception
Deprecated. Use bufSizeYUV(int, int, int, int) instead.

Throws:
java.lang.Exception

getScalingFactors

public static TJScalingFactor[] getScalingFactors()
                                           throws java.lang.Exception
Returns a list of fractional scaling factors that the JPEG decompressor in this implementation of TurboJPEG supports.

Returns:
a list of fractional scaling factors that the JPEG decompressor in this implementation of TurboJPEG supports
Throws:
java.lang.Exception