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Package org.libjpegturbo.turbojpeg

Class TJ

  • java.lang.Object

    • org.libjpegturbo.turbojpeg.TJ
public final classTJextends java.lang.Object

TurboJPEG utility class (cannot be instantiated)

Field Summary

Fields | Modifier and Type | Field | Description | | --- | --- | --- | | 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 | ERR_FATAL | The error was fatal and non-recoverable. | | static int | ERR_WARNING | The error was non-fatal and recoverable, but the destination image may still be corrupt. | | static int | FLAG_ACCURATEDCT | Deprecated. Use PARAM_FASTDCT instead.

| | static int | FLAG_BOTTOMUP | Deprecated. Use PARAM_BOTTOMUP instead.

| | static int | FLAG_FASTDCT | Deprecated. Use PARAM_FASTDCT instead.

| | static int | FLAG_FASTUPSAMPLE | Deprecated. Use PARAM_FASTUPSAMPLE instead.

| | static int | FLAG_LIMITSCANS | Deprecated. Use PARAM_SCANLIMIT instead.

| | static int | FLAG_PROGRESSIVE | Deprecated. Use PARAM_PROGRESSIVE instead.

| | static int | FLAG_STOPONWARNING | Deprecated. Use PARAM_STOPONWARNING instead.

| | static int | NUMCS | The number of JPEG colorspaces | | static int | NUMERR | The number of error codes | | static int | NUMPF | The number of pixel formats | | static int | NUMSAMP | The number of chrominance subsampling options | | static int | PARAM_ARITHMETIC | Arithmetic entropy coding | | static int | PARAM_BOTTOMUP | Row order in packed-pixel source/destination images | | static int | PARAM_COLORSPACE | JPEG colorspace | | static int | PARAM_DENSITYUNITS | JPEG pixel density units | | static int | PARAM_FASTDCT | DCT/IDCT algorithm [lossy compression and decompression] | | static int | PARAM_FASTUPSAMPLE | Chrominance upsampling algorithm [lossy decompression only] | | static int | PARAM_JPEGHEIGHT | JPEG height (in pixels) [decompression only, read-only] | | static int | PARAM_JPEGWIDTH | JPEG width (in pixels) [decompression only, read-only] | | static int | PARAM_LOSSLESS | Lossless JPEG | | static int | PARAM_LOSSLESSPSV | Lossless JPEG predictor selection value (PSV) | | static int | PARAM_LOSSLESSPT | Lossless JPEG point transform (Pt) | | static int | PARAM_MAXMEMORY | Memory limit for intermediate buffers | | static int | PARAM_MAXPIXELS | Image size limit [decompression, lossless transformation] | | static int | PARAM_OPTIMIZE | Huffman table optimization [lossy compression, lossless transformation] | | static int | PARAM_PRECISION | JPEG data precision (bits per sample) [decompression only, read-only] | | static int | PARAM_PROGRESSIVE | Progressive JPEG | | static int | PARAM_QUALITY | Perceptual quality of lossy JPEG images [compression only] | | static int | PARAM_RESTARTBLOCKS | JPEG restart marker interval in MCUs [lossy compression only] | | static int | PARAM_RESTARTROWS | JPEG restart marker interval in MCU rows [compression only] | | static int | PARAM_SCANLIMIT | Progressive JPEG scan limit for lossy JPEG images [decompression, lossless transformation] | | static int | PARAM_STOPONWARNING | Error handling behavior | | static int | PARAM_SUBSAMP | Chrominance subsampling level | | static int | PARAM_XDENSITY | JPEG horizontal pixel density | | static int | PARAM_YDENSITY | JPEG vertical pixel density | | 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_441 | 4:4:1 chrominance subsampling | | static int | SAMP_444 | 4:4:4 chrominance subsampling (no chrominance subsampling) | | static int | SAMP_GRAY | Grayscale | | static int | SAMP_UNKNOWN | Unknown subsampling | | static java.awt.Rectangle | UNCROPPED | A java.awt.Rectangle instance that specifies no cropping | | static TJScalingFactor | UNSCALED | A TJScalingFactor instance that specifies a scaling factor of 1/1 (no scaling) |

Method Summary

All Methods Static Methods Concrete Methods | Modifier and Type | Method | Description | | --- | --- | --- | | 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 align, int height, int subsamp) | 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. | | static int | getAlphaOffset​(int pixelFormat) | For the given pixel format, returns the number of samples that the alpha component is offset from the start of the pixel. | | static int | getBlueOffset​(int pixelFormat) | For the given pixel format, returns the number of samples 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 samples that the green component is offset from the start of the pixel. | | static int | getMCUHeight​(int subsamp) | Returns the iMCU height for the given level of chrominance subsampling. | | static int | getMCUWidth​(int subsamp) | Returns the iMCU width for the given level of chrominance subsampling. | | static int | getPixelSize​(int pixelFormat) | Returns the pixel size (in samples) for the given pixel format. | | static int | getRedOffset​(int pixelFormat) | For the given pixel format, returns the number of samples 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 supports. | | static int | planeHeight​(int componentID, int height, int subsamp) | Returns the plane height of a YUV image plane with the given parameters. | | static int | planeSizeYUV​(int componentID, int width, int stride, int height, int subsamp) | Returns the size of the buffer (in bytes) required to hold a YUV image plane with the given parameters. | | static int | planeWidth​(int componentID, int width, int subsamp) | Returns the plane width of a YUV image plane with the given parameters. |

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Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

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NUMSAMP

public static final int NUMSAMP

The number of chrominance subsampling options See Also:Constant Field Values

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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.

See Also:Constant Field Values

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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.

See Also:Constant Field Values

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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.

See Also:Constant Field Values

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SAMP_GRAY

public static final int SAMP_GRAY

Grayscale

The JPEG or YUV image will contain no chrominance components.

See Also:Constant Field Values

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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: 4:4:0 subsampling is not fully accelerated in libjpeg-turbo.

See Also:Constant Field Values

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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. All else being equal, a JPEG image with 4:1:1 subsampling is almost exactly the same size as a JPEG image 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: 4:1:1 subsampling is not fully accelerated in libjpeg-turbo.

See Also:Constant Field Values

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SAMP_441

public static final int SAMP_441

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. All else being equal, a JPEG image with 4:4:1 subsampling is almost exactly the same size as a JPEG image 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: 4:4:1 subsampling is not fully accelerated in libjpeg-turbo.

See Also:Constant Field Values

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SAMP_UNKNOWN

public static final int SAMP_UNKNOWN

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

  - decompressed into planar YUV images, 
  - losslessly transformed if [`TJTransform.OPT_CROP`](TJTransform.html#OPT_CROP) is specified and [`TJTransform.OPT_GRAY`](TJTransform.html#OPT_GRAY) is not specified, or 
  - partially decompressed using a cropping region.

See Also:Constant Field Values

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NUMPF

public static final int NUMPF

The number of pixel formats See Also:Constant Field Values

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PF_RGB

public static final int PF_RGB

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.

See Also:Constant Field Values

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PF_BGR

public static final int PF_BGR

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.

See Also:Constant Field Values

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PF_RGBX

public static final int PF_RGBX

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/encoding and undefined when decompressing/decoding.

See Also:Constant Field Values

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PF_BGRX

public static final int PF_BGRX

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/encoding and undefined when decompressing/decoding.

See Also:Constant Field Values

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PF_XBGR

public static final int PF_XBGR

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/encoding and undefined when decompressing/decoding.

See Also:Constant Field Values

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PF_XRGB

public static final int PF_XRGB

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/encoding and undefined when decompressing/decoding.

See Also:Constant Field Values

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PF_GRAY

public static final int PF_GRAY

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.)

See Also:Constant Field Values

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PF_RGBA

public static final int PF_RGBA

RGBA pixel format

This is the same as PF_RGBX, except that when decompressing/decoding, the X component is guaranteed to be equal to the maximum sample value, which can be interpreted as an opaque alpha channel.

See Also:Constant Field Values

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PF_BGRA

public static final int PF_BGRA

BGRA pixel format

This is the same as PF_BGRX, except that when decompressing/decoding, the X component is guaranteed to be equal to the maximum sample value, which can be interpreted as an opaque alpha channel.

See Also:Constant Field Values

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PF_ABGR

public static final int PF_ABGR

ABGR pixel format

This is the same as PF_XBGR, except that when decompressing/decoding, the X component is guaranteed to be equal to the maximum sample value, which can be interpreted as an opaque alpha channel.

See Also:Constant Field Values

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PF_ARGB

public static final int PF_ARGB

ARGB pixel format

This is the same as PF_XRGB, except that when decompressing/decoding, the X component is guaranteed to be equal to the maximum sample value, which can be interpreted as an opaque alpha channel.

See Also:Constant Field Values

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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 packed-pixel CMYK images into YCCK JPEG images (see CS_YCCK) and decompressing YCCK JPEG images into packed-pixel CMYK images.

See Also:Constant Field Values

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NUMCS

public static final int NUMCS

The number of JPEG colorspaces See Also:Constant Field Values

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CS_RGB

public static final int CS_RGB

RGB colorspace

When generating 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 generated from and decompressed to packed-pixel images with any of the extended RGB or grayscale pixel formats, but they cannot be generated from or decompressed to planar YUV images.

See Also:Constant Field Values

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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 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. Historically, the analog equivalent of this transformation allowed the same signal to be displayed to both black & white and color televisions, but JPEG images use YCbCr primarily because it allows the color data to be optionally subsampled in order to reduce network and disk usage. YCbCr is the most common JPEG colorspace, and YCbCr JPEG images can be generated from and decompressed to packed-pixel images with any of the extended RGB or grayscale pixel formats. YCbCr JPEG images can also be generated from and decompressed to planar YUV images.

See Also:Constant Field Values

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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 generated from and decompressed to packed-pixel images with any of the extended RGB or grayscale pixel formats, or they can be generated from and decompressed to planar YUV images.

See Also:Constant Field Values

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CS_CMYK

public static final int CS_CMYK

CMYK colorspace

When generating 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 generated from and decompressed to packed-pixel images with the CMYK pixel format.

See Also:Constant Field Values

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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 generated from and decompressed to packed-pixel images with the CMYK pixel format.

See Also:Constant Field Values

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PARAM_STOPONWARNING

public static final int PARAM_STOPONWARNING

Error handling behavior

Value

  - `0` _[default]_ Allow the current compression/decompression/transform operation to complete unless a fatal error is encountered. 
  - `1` Immediately discontinue the current compression/decompression/transform operation if a warning (non-fatal error) occurs.

See Also:Constant Field Values

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PARAM_BOTTOMUP

public static final int PARAM_BOTTOMUP

Row order in packed-pixel source/destination images

Value

  - `0` _[default]_ top-down (X11) order 
  - `1` bottom-up (Windows, OpenGL) order

See Also:Constant Field Values

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PARAM_QUALITY

public static final int PARAM_QUALITY

Perceptual quality of lossy JPEG images [compression only]

Value

  - `1`-`100` (`1` = worst quality but best compression, `100` = best quality but worst compression) _[no default; must be explicitly specified]_

See Also:Constant Field Values

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PARAM_SUBSAMP

public static final int PARAM_SUBSAMP

Chrominance subsampling level

The JPEG or YUV image uses (decompression, decoding) or will use (lossy compression, encoding) the specified level of chrominance subsampling.

When pixels are converted from RGB to YCbCr (see CS_YCbCr) or from CMYK to YCCK (see 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 quality. (The human eye is more sensitive to small changes in brightness than to small changes in color.) This is called "chrominance subsampling".

Value

  - One of [`TJ.SAMP_*`](#SAMP_444) _[no default; must be explicitly specified for lossy compression, encoding, and decoding]_

See Also:Constant Field Values

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PARAM_JPEGWIDTH

public static final int PARAM_JPEGWIDTH

JPEG width (in pixels) [decompression only, read-only] See Also:Constant Field Values

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PARAM_JPEGHEIGHT

public static final int PARAM_JPEGHEIGHT

JPEG height (in pixels) [decompression only, read-only] See Also:Constant Field Values

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PARAM_PRECISION

public static final int PARAM_PRECISION

JPEG data precision (bits per sample) [decompression only, read-only]

The JPEG image uses the specified number of bits per sample.

Value

  - `8`, `12`, or `16`

12-bit data precision implies PARAM_OPTIMIZE unless PARAM_ARITHMETIC is set.

See Also:Constant Field Values

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PARAM_COLORSPACE

public static final int PARAM_COLORSPACE

JPEG colorspace

The JPEG image uses (decompression) or will use (lossy compression) the specified colorspace.

Value

  - One of [`TJ.CS_*`](#CS_RGB) _[default for lossy compression: automatically selected based on the subsampling level and pixel format]_

See Also:Constant Field Values

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PARAM_FASTUPSAMPLE

public static final int PARAM_FASTUPSAMPLE

Chrominance upsampling algorithm [lossy decompression only]

Value

  - `0` _[default]_ Use smooth upsampling when decompressing a JPEG image that was generated using chrominance subsampling. This creates a smooth transition between neighboring chrominance components in order to reduce upsampling artifacts in the decompressed image. 
  - `1` Use the fastest chrominance upsampling algorithm available, which may combine upsampling with color conversion.

See Also:Constant Field Values

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PARAM_FASTDCT

public static final int PARAM_FASTDCT

DCT/IDCT algorithm [lossy compression and decompression]

Value

  - `0` _[default]_ Use the most accurate DCT/IDCT algorithm available. 
  - `1` Use the fastest DCT/IDCT algorithm available.

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:

  - The "fast" and "accurate" DCT/IDCT algorithms perform similarly on modern x86/x86-64 CPUs that support AVX2 instructions. 
  - The "fast" algorithm is generally only about 5-15% faster than the "accurate" algorithm on other types of CPUs. 
  - 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. 
  - For JPEG quality levels above 97, the "fast" algorithm degrades and is not fully accelerated, so it is slower than the "accurate" algorithm.

See Also:Constant Field Values

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PARAM_OPTIMIZE

public static final int PARAM_OPTIMIZE

Huffman table optimization [lossy compression, lossless transformation]

Value

  - `0` _[default]_ The JPEG image will use the default Huffman tables. 
  - `1` Optimal Huffman tables will be computed for the JPEG image. For lossless transformation, this can also be specified using [`TJTransform.OPT_OPTIMIZE`](TJTransform.html#OPT_OPTIMIZE).

Huffman table optimization improves compression slightly (generally 5% or less), but it reduces compression performance considerably.

See Also:Constant Field Values

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PARAM_PROGRESSIVE

public static final int PARAM_PROGRESSIVE

Progressive JPEG

In a progressive JPEG image, the DCT coefficients are split across multiple "scans" of increasing quality. Thus, a low-quality scan containing the lowest-frequency DCT coefficients can be transmitted first and refined with subsequent higher-quality scans containing higher-frequency DCT coefficients. When using Huffman entropy coding, the progressive JPEG format also provides an "end-of-bands (EOB) run" feature that allows large groups of zeroes, potentially spanning multiple MCUs, to be represented using only a few bytes.

Value

  - `0` _[default for compression, lossless transformation]_ The lossy JPEG image is (decompression) or will be (compression, lossless transformation) single-scan. 
  - `1` The lossy JPEG image is (decompression) or will be (compression, lossless transformation) progressive. For lossless transformation, this can also be specified using [`TJTransform.OPT_PROGRESSIVE`](TJTransform.html#OPT_PROGRESSIVE).

Progressive JPEG images generally have better compression ratios than single-scan JPEG images (much better if the image has large areas of solid color), but progressive JPEG compression and decompression is considerably slower than single-scan JPEG compression and decompression. Can be combined with PARAM_ARITHMETIC. Implies PARAM_OPTIMIZE unless PARAM_ARITHMETIC is also set.

See Also:Constant Field Values

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PARAM_SCANLIMIT

public static final int PARAM_SCANLIMIT

Progressive JPEG scan limit for lossy JPEG images [decompression, lossless transformation]

Setting this parameter causes 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 this report.

Value

  - maximum number of progressive JPEG scans that the decompression and transform operations will process _[default: `0` (no limit)]_

See Also:PARAM_PROGRESSIVE, Constant Field Values

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PARAM_ARITHMETIC

public static final int PARAM_ARITHMETIC

Arithmetic entropy coding

Value

  - `0` _[default for compression, lossless transformation]_ The lossy JPEG image uses (decompression) or will use (compression, lossless transformation) Huffman entropy coding. 
  - `1` The lossy JPEG image uses (decompression) or will use (compression, lossless transformation) arithmetic entropy coding. For lossless transformation, this can also be specified using [`TJTransform.OPT_ARITHMETIC`](TJTransform.html#OPT_ARITHMETIC).

Arithmetic entropy coding generally improves compression relative to Huffman entropy coding, but it reduces compression and decompression performance considerably. Can be combined with PARAM_PROGRESSIVE.

See Also:Constant Field Values

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PARAM_LOSSLESS

public static final int PARAM_LOSSLESS

Lossless JPEG

Value

  - `0` _[default for compression]_ The JPEG image is (decompression) or will be (compression) lossy/DCT-based. 
  - `1` The JPEG image is (decompression) or will be (compression) lossless/predictive.

In most cases, lossless JPEG compression and decompression is considerably slower than lossy JPEG compression and decompression, 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:

  - Colorspace conversion (lossless JPEG images always use [`CS_RGB`](#CS_RGB), [`CS_GRAY`](#CS_GRAY), or [`CS_CMYK`](#CS_CMYK), depending on the pixel format of the source image) 
  - Chrominance subsampling (lossless JPEG images always use [`SAMP_444`](#SAMP_444)) 
  - JPEG quality selection 
  - DCT/IDCT algorithm selection 
  - Progressive JPEG 
  - Arithmetic entropy coding 
  - Compression from/decompression to planar YUV images 
  - Decompression scaling 
  - Lossless transformation

See Also:PARAM_LOSSLESSPSV, PARAM_LOSSLESSPT, Constant Field Values

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PARAM_LOSSLESSPSV

public static final int PARAM_LOSSLESSPSV

Lossless JPEG predictor selection value (PSV)

Value

  - `1`-`7` _[default for compression: `1`]_

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:

PSVPredictor
1Ra
2Rb
3Rc
4Ra + Rb – Rc
5Ra + (Rb – Rc) / 2
6Rb + (Ra – Rc) / 2
7(Ra + Rb) / 2

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 Also:PARAM_LOSSLESS, Constant Field Values

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PARAM_LOSSLESSPT

public static final int PARAM_LOSSLESSPT

Lossless JPEG point transform (Pt)

Value

  - `0` through _ **precision** - 1_, where **_precision_** is the JPEG data precision in bits _[default for compression: `0`]_

A point transform value of 0 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 Also:PARAM_LOSSLESS, PARAM_PRECISION, Constant Field Values

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PARAM_RESTARTBLOCKS

public static final int PARAM_RESTARTBLOCKS

JPEG restart marker interval in MCUs [lossy compression only]

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.

In typical JPEG images, an MCU (Minimum Coded Unit) is the minimum set of interleaved "data units" (8x8 DCT blocks if the image is lossy or samples if the image is lossless) necessary to represent at least one data unit per component. (For example, an MCU in an interleaved lossy JPEG image that uses 4:2:2 subsampling consists of two luminance blocks followed by one block for each chrominance component.) In single-component or non-interleaved JPEG images, an MCU is the same as a data unit.

Value

  - the number of MCUs between each restart marker _[default: `0` (no restart markers)]_

Setting this parameter to a non-zero value sets PARAM_RESTARTROWS to 0.

See Also:Constant Field Values

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PARAM_RESTARTROWS

public static final int PARAM_RESTARTROWS

JPEG restart marker interval in MCU rows [compression only]

See PARAM_RESTARTBLOCKS for a description of restart markers and MCUs. An MCU row is a row of MCUs spanning the entire width of the image.

Value

  - the number of MCU rows between each restart marker _[default: `0` (no restart markers)]_

Setting this parameter to a non-zero value sets PARAM_RESTARTBLOCKS to 0.

See Also:Constant Field Values

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PARAM_XDENSITY

public static final int PARAM_XDENSITY

JPEG horizontal pixel density

Value

  - The JPEG image has (decompression) or will have (compression) the specified horizontal pixel density _[default for compression: `1`]_.

This value is stored in or read from the JPEG header. It does not affect the contents of the JPEG image.

This parameter has no effect unless the JPEG colorspace (see PARAM_COLORSPACE) is CS_YCbCr or CS_GRAY.

See Also:PARAM_DENSITYUNITS, Constant Field Values

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PARAM_YDENSITY

public static final int PARAM_YDENSITY

JPEG vertical pixel density

Value

  - The JPEG image has (decompression) or will have (compression) the specified vertical pixel density _[default for compression: `1`]_.

This value is stored in or read from the JPEG header. It does not affect the contents of the JPEG image.

This parameter has no effect unless the JPEG colorspace (see PARAM_COLORSPACE) is CS_YCbCr or CS_GRAY.

See Also:PARAM_DENSITYUNITS, Constant Field Values

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PARAM_DENSITYUNITS

public static final int PARAM_DENSITYUNITS

JPEG pixel density units

Value

  - `0` _[default for compression]_ The pixel density of the JPEG image is expressed (decompression) or will be expressed (compression) in unknown units. 
  - `1` The pixel density of the JPEG image is expressed (decompression) or will be expressed (compression) in units of pixels/inch. 
  - `2` The pixel density of the JPEG image is expressed (decompression) or will be expressed (compression) in units of pixels/cm.

This value is stored in or read from the JPEG header. It does not affect the contents of the JPEG image.

This parameter has no effect unless the JPEG colorspace (see PARAM_COLORSPACE) is CS_YCbCr or CS_GRAY.

See Also:PARAM_XDENSITY, PARAM_YDENSITY, Constant Field Values

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PARAM_MAXMEMORY

public static final int PARAM_MAXMEMORY

Memory limit for intermediate buffers

Value

  - the maximum amount of memory (in megabytes) that will be allocated for intermediate buffers, which are used with progressive JPEG compression and decompression, Huffman table optimization, lossless JPEG compression, and lossless transformation _[default: `0` (no limit)]_

See Also:Constant Field Values

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PARAM_MAXPIXELS

public static final int PARAM_MAXPIXELS

Image size limit [decompression, lossless transformation]

Setting this parameter causes 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.

Value

  - maximum number of pixels that the decompression and transform operations will process _[default: `0` (no limit)]_

See Also:Constant Field Values

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FLAG_BOTTOMUP

@Deprecated
public static final int FLAG_BOTTOMUP

Deprecated. Use PARAM_BOTTOMUP instead.

See Also:Constant Field Values

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FLAG_FASTUPSAMPLE

@Deprecated
public static final int FLAG_FASTUPSAMPLE

Deprecated. Use PARAM_FASTUPSAMPLE instead.

See Also:Constant Field Values

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FLAG_FASTDCT

@Deprecated
public static final int FLAG_FASTDCT

Deprecated. Use PARAM_FASTDCT instead.

See Also:Constant Field Values

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FLAG_ACCURATEDCT

@Deprecated
public static final int FLAG_ACCURATEDCT

Deprecated. Use PARAM_FASTDCT instead.

See Also:Constant Field Values

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FLAG_STOPONWARNING

@Deprecated
public static final int FLAG_STOPONWARNING

Deprecated. Use PARAM_STOPONWARNING instead.

See Also:Constant Field Values

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FLAG_PROGRESSIVE

@Deprecated
public static final int FLAG_PROGRESSIVE

Deprecated. Use PARAM_PROGRESSIVE instead.

See Also:Constant Field Values

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FLAG_LIMITSCANS

@Deprecated
public static final int FLAG_LIMITSCANS

Deprecated. Use PARAM_SCANLIMIT instead.

See Also:Constant Field Values

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NUMERR

public static final int NUMERR

The number of error codes See Also:Constant Field Values

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ERR_WARNING

public static final int ERR_WARNING

The error was non-fatal and recoverable, but the destination image may still be corrupt.

NOTE: Due to the design of the TurboJPEG Java API, only certain methods (specifically, 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.

See Also:Constant Field Values

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ERR_FATAL

public static final int ERR_FATAL

The error was fatal and non-recoverable. See Also:Constant Field Values

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UNSCALED

public static final[TJScalingFactor](TJScalingFactor.html "class in org.libjpegturbo.turbojpeg")UNSCALED

A TJScalingFactor instance that specifies a scaling factor of 1/1 (no scaling)

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UNCROPPED

public static final java.awt.Rectangle UNCROPPED

A java.awt.Rectangle instance that specifies no cropping

Method Detail

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getMCUWidth

public static int getMCUWidth​(int subsamp)

Returns the iMCU width for the given level of chrominance subsampling.

In a typical lossy JPEG image, 8x8 blocks of DCT coefficients for each component are interleaved in a single scan. If the image uses chrominance subsampling, then multiple luminance blocks are stored together, followed by a single block for each chrominance component. The minimum set of full-resolution luminance block(s) and corresponding (possibly subsampled) chrominance blocks necessary to represent at least one DCT block per component is called a "Minimum Coded Unit" or "MCU". (For example, an MCU in an interleaved lossy JPEG image that uses 4:2:2 subsampling consists of two luminance blocks followed by one block for each chrominance component.) In a non-interleaved lossy JPEG image, each component is stored in a separate scan, and an MCU is a single DCT block, so we use the term "iMCU" (interleaved MCU) to refer to the equivalent of an MCU in an interleaved JPEG image. For the common case of interleaved JPEG images, an iMCU is the same as an MCU.

Parameters:subsamp - the level of chrominance subsampling (one of SAMP_*)Returns:the iMCU width for the given level of chrominance subsampling.

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getMCUHeight

public static int getMCUHeight​(int subsamp)

Returns the iMCU height for the given level of chrominance subsampling.

In a typical lossy JPEG image, 8x8 blocks of DCT coefficients for each component are interleaved in a single scan. If the image uses chrominance subsampling, then multiple luminance blocks are stored together, followed by a single block for each chrominance component. The minimum set of full-resolution luminance block(s) and corresponding (possibly subsampled) chrominance blocks necessary to represent at least one DCT block per component is called a "Minimum Coded Unit" or "MCU". (For example, an MCU in an interleaved lossy JPEG image that uses 4:2:2 subsampling consists of two luminance blocks followed by one block for each chrominance component.) In a non-interleaved lossy JPEG image, each component is stored in a separate scan, and an MCU is a single DCT block, so we use the term "iMCU" (interleaved MCU) to refer to the equivalent of an MCU in an interleaved JPEG image. For the common case of interleaved JPEG images, an iMCU is the same as an MCU.

Parameters:subsamp - the level of chrominance subsampling (one of SAMP_*)Returns:the iMCU height for the given level of chrominance subsampling.

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getPixelSize

public static int getPixelSize​(int pixelFormat)

Returns the pixel size (in samples) for the given pixel format. Parameters:pixelFormat - the pixel format (one of PF_*)Returns:the pixel size (in samples) for the given pixel format.

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getRedOffset

public static int getRedOffset​(int pixelFormat)

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 TJ.PF_BGRX is stored in char pixel[], then the red component is pixel[TJ.getRedOffset(TJ.PF_BGRX)]. Parameters:pixelFormat - the pixel format (one of PF_*)Returns:the red offset for the given pixel format, or -1 if the pixel format does not have a red component.

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getGreenOffset

public static int getGreenOffset​(int pixelFormat)

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 TJ.PF_BGRX is stored in char pixel[], then the green component is pixel[TJ.getGreenOffset(TJ.PF_BGRX)]. Parameters:pixelFormat - the pixel format (one of PF_*)Returns:the green offset for the given pixel format, or -1 if the pixel format does not have a green component.

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getBlueOffset

public static int getBlueOffset​(int pixelFormat)

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 TJ.PF_BGRX is stored in char pixel[], then the blue component is pixel[TJ.getBlueOffset(TJ.PF_BGRX)]. Parameters:pixelFormat - the pixel format (one of PF_*)Returns:the blue offset for the given pixel format, or -1 if the pixel format does not have a blue component.

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getAlphaOffset

public static int getAlphaOffset​(int pixelFormat)

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 TJ.PF_BGRA is stored in char pixel[], then the alpha component is pixel[TJ.getAlphaOffset(TJ.PF_BGRA)]. Parameters:pixelFormat - the pixel format (one of PF_*)Returns:the alpha offset for the given pixel format, or -1 if the pixel format does not have a alpha component.

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bufSize

public 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. Parameters:width - the width (in pixels) of the JPEG imageheight - the height (in pixels) of the JPEG imagejpegSubsamp - the level of chrominance subsampling to be used when generating the JPEG image (one of TJ.SAMP_*.) SAMP_UNKNOWN is treated like 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 SAMP_444.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.

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bufSizeYUV

public static int bufSizeYUV​(int width,
                             int align,
                             int height,
                             int subsamp)

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. Parameters:width - the width (in pixels) of the YUV imagealign - 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.)height - the height (in pixels) of the YUV imagesubsamp - 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 unified planar YUV image with the given width, height, and level of chrominance subsampling.

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planeSizeYUV

public static int planeSizeYUV​(int componentID,
                               int width,
                               int stride,
                               int height,
                               int subsamp)

Returns the size of the buffer (in bytes) required to hold a YUV image plane with the given parameters. Parameters:componentID - ID number of the image plane (0 = Y, 1 = U/Cb, 2 = V/Cr)width - width (in pixels) of the YUV image. NOTE: This is the width of the whole image, not the plane width.stride - bytes per row in the image plane.height - height (in pixels) of the YUV image. NOTE: This is the height of the whole image, not the plane height.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 image plane with the given parameters.

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planeWidth

public static int planeWidth​(int componentID,
                             int width,
                             int subsamp)

Returns the plane width of a YUV image plane with the given parameters. Refer to YUVImage for a description of plane width. Parameters:componentID - ID number of the image plane (0 = Y, 1 = U/Cb, 2 = V/Cr)width - width (in pixels) of the YUV imagesubsamp - the level of chrominance subsampling used in the YUV image (one of TJ.SAMP_*)Returns:the plane width of a YUV image plane with the given parameters.

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planeHeight

public static int planeHeight​(int componentID,
                              int height,
                              int subsamp)

Returns the plane height of a YUV image plane with the given parameters. Refer to YUVImage for a description of plane height. Parameters:componentID - ID number of the image plane (0 = Y, 1 = U/Cb, 2 = V/Cr)height - height (in pixels) of the YUV imagesubsamp - the level of chrominance subsampling used in the YUV image (one of TJ.SAMP_*)Returns:the plane height of a YUV image plane with the given parameters.

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getScalingFactors

public static[TJScalingFactor](TJScalingFactor.html "class in org.libjpegturbo.turbojpeg")[] getScalingFactors()

Returns a list of fractional scaling factors that the JPEG decompressor supports. Returns:a list of fractional scaling factors that the JPEG decompressor supports.