ImageGear for .NET
JPEG2000
ImageGear for .NET User Guide > ImageGear Imaging Formats Reference > ImageGear Supported File Formats Reference > JPEG2000
Full Name JPEG2000
Format ID ImGearFormats.JPEG2K
File Extension(s) *.jp2, *.jpc, *.j2k, *.j2c
Data Type Raster Image
Data Encoding Binary
IG Multipage Support No
IG Alpha Channel Support Read/write
IG Metadata Update Support Page
IG Platforms Support WIN32, WIN64, .NET, .NET64
JPEG2000 format requires ImageGear.Formats.JPEG2K Namespace.

ImageGear Supported Versions

ISO/IEC 15444-1:2000

ImageGear Supported Features

ImageGear Read Support

For Raw Code-stream JPEG 2000 files:

For JP2-compatible JPEG 2000 files:

ImageGear Write Support

For Raw Codestream JPEG 2000 files:

For JP2-compatible JPEG 2000 files:

ImageGear Filter Control Parameters

Filter Control Parameter Type Default Value Available Values Description
CodeBlockSize Int 64 4, 8, 16, 32, 64

Affects image saving.

Nominal code-block dimension. Actual dimension is the subject to precinct, tile and image dimensions.

CodeBlockStyle ImGearJPEG2KCodeBlockStyles Enumeration ImGearJPEG2KCodeBlockStyles Enumeration.ALL_OFF Any combination of values from ImGearJPEG2KCodeBlockStyles Enumeration values.

Affects image saving.

Block coder mode switches. Any combination of values from ImGearJPEG2KCodeBlockStyles Enumeration is legal.

CpuOptimizationMode ImGearJPEG2KCpuOptimizationMode Enumeration ImGearJPEG2KCpuOptimizationMode Enumeration.EnableAll Any ImGearJPEG2KCpuOptimizationMode value. Allows disabling CPU optimization features if those are not supported by the OS.
DiscardLevels Int 0 Any non-negative integer value.

Affects image loading.

Allows loading a smaller version of the image, which takes less time and memory than loading the whole image. This parameter indicates the number of highest resolution DWT levels which will be skipped during the reading. Dimensions of the image loaded with DiscardLevels = N will be 2^N times smaller than the actual image dimensions. If the specified number exceeds the number of DWT levels in the image, the lowest resolution level will be loaded. For this parameter to take effect, the image must have more than one DWT level. Use the WaveletLevels parameter to specify the number of DWT levels for JPEG 2000 image saving.

EbcotBitplaneShift Int 0 0, 3

This control parameter should be used in combination with the CodeBlockStyle control parameter. Setting EbcotBitplaneShift to 3 and CodeBlockStyle to ImGearJPEG2KCodeBlockStyles.BYPASS enables a notable encoder speed-up between 10% and 20% over regular coding bypass mode, and a speed-up of up to 40% over regular coding mode. A similar speed-up can be expected in decoding images that have been encoded in this mode.

Images saved in this mode are slightly larger in size but load faster. A value of 0 disables the feature; a value of 3 enables it. The rest of the values are reserved and result in an error upon attempting to set. The feature is disabled by default.

FileFormat ImGearJPEG2KType Enumeration ImGearJPEG2KType Enumeration.FILE_FORMAT Any ImGearJPEG2KType Enumeration value

Affects image saving.

Specifies whether to save the file as a JP2-compatible file or as a raw JPEG 2000 code-stream. JP2 compatible files contain various metadata, such as resolution, color space, palette, XML, etc. Raw code-streams do not store any metadata.

Mode ImGearJPEG2KModes Enumeration ImGearJPEG2KModes Enumeration.FAST Any ImGearJPEG2KModes Enumeration value.

This parameter has been deprecated.
ProgressionOrder ImGearJPEG2KProgressionOrders Enumeration ImGearJPEG2KProgressionOrders Enumeration.LRCP Any ImGearJPEG2KProgressionOrders Enumeration value.

Affects image saving.

This parameter specifies the progression order to be used by the result file. See ImGearJPEG2KProgressionOrders Enumeration for available progression orders.

QualityLayers Double[] new Double[0] Array of one or more double values.

Affects image saving.

This parameter represents a more powerful version of the RateBytes control parameter. Its value is an array of one or more bit-rates, expressed in terms of the ratio between the total number of compressed bits in the code stream (including code stream header, but not including JP2 header) and the number of pixels in the image (image width * height). The number of elements in the array represents the number of quality layers. Each value in the array represents the overall bit-rate of this layer, rather than the difference between this layer and the previous layer.

In order to use the maximum quality for the last layer, set the last element of the array to 0.0.

Setting the last element in the array to 0.0 does not guarantee that the image will be saved without a loss of quality. See Saving JPEG 2000 and JPX Images in Lossless Mode for more details.

Example:

Set QualityLayers to {0.01, 0.1, 0.5}

If the source image dimensions are 800 x 600 = 480000 pixels, the array used in the example will result in the following layer sizes:

  • 1st layer: 480000 * 0.01 / 8 = 600 bytes
  • 1st and 2nd layers: 480000 * 0.1 / 8 = 6000 bytes
  • 1st, 2nd, and 3rd layers (whole codestream): 480000 * 0.5 / 8 = 30000 bytes
QuantizationStep Double -1.0 Any negative value; 0.0…2.0

Affects image saving.

This control parameter is the base step size to be used in deriving irreversible quantization step sizes for every sub-band.

Any negative value results in automatic selection of the quantization step size. This is the recommended mode.

RateBytes Int 0 Any non-negative integer value.

Affects image saving.

This control parameter specifies the maximal size of the saved code stream in bytes. A zero value instructs the filter to use the highest compression quality.

Using the same non-zero value for different images causes the filter to write files with a different compression rate. In order to provide a consistent compression rate across images of different sizes, calculate this parameter for each image, based on the product of the image width and height, or on the uncompressed DIB size.

Alternatively, use QualityLayers control parameter, which uses relative coefficients.

Setting RateBytes to 0 does not guarantee that the image will be saved without a loss of quality. See Saving JPEG 2000 and JPX Images in Lossless Mode for more details.
StitchTiles bool true true, false

Affects image loading.

This parameter specifies how tiled images should be loaded. If true then ImageGear loads and stitches (composes together) all tiles automatically into the resulting image. If false then ImageGear loads a single tile.

TileHeight Int 0 Any non-negative integer value.

Affects image loading.

Specifies the height of one tile in the reference grid. A zero value indicates the image's height.

TileWidth Int 0 Any non-negative integer value.

Affects image loading.

Specifies the width of one tile in reference grid. A zero value indicates the image's width.

ViewHeight Int 0 Any non-negative integer value.

Affects image loading.

Allows loading a smaller version of the image, which takes less time and memory than loading the whole image. If the value is nonzero, or is greater than the image height, ImageGear only loads DWT levels whose height is not greater than the parameter value. Dimensions of each decomposition level are twice greater than that of the previous level. A zero value indicates the initial image's height. This parameter is similar to DiscardLevels in that it allows you to select the highest resolution level for image loading.

ViewWidth Int 0 Any non-negative integer value.

Affects image loading.

Allows loading a smaller version of the image, which takes less time and memory than loading the whole image. If the value is nonzero, or is greater than the image width, ImageGear only loads DWT levels whose width is not greater than the parameter value. Dimensions of each decomposition level are twice greater than that of the previous level. A zero value indicates the initial image's height. This parameter is similar to DiscardLevels in that it allows you to select the highest resolution level for image loading.

WaveletFilter ImGearJPEG2KFilters Enumeration ImGearJPEG2KFilters Enumeration.AUTO Any ImGearJPEG2KFilters Enumeration value.

Affects image saving.

Specifies the type of Wavelet filter (Auto, Reversible, or Irreversible) to be used for Discrete Wavelet Transform.

Selecting the ImGearJPEG2KFilters.REVERSIBLE filter does not guarantee that the image will be saved without a loss of quality. See Saving JPEG 2000 and JPX Images in Lossless Mode for more details.

Applying irreversible transform to indexed (paletted) images may result in significant degradation of image quality, because small changes in pixel values may result in significant visual difference after application of a palette. Consider using reversible transform for paletted images, or promoting images to true color and then using the reversible transform.

 

WaveletLevels Int -1 -1 … 16

Affects image saving.

Specifies the quantity of decomposition levels (stages) for the image being saved. The main purpose of each level is to provide the ability for the reader to faster decompress the reduced size version of the original image.

Dimensions of the Nth level are 2^N times smaller than the actual image dimensions.

Setting this parameter to -1 tells ImageGear to select the value automatically. Currently, ImageGear uses 5 levels for all types of images in this mode.

Non-Image Data Structure

ImageGear JPEG2K format filter allows you to work with non-image data stored in supported file formats. It provides metadata tags that make possible manipulating with such kinds of non-image information:

The following metadata tags are available to work with JP2 files:

"AlphaMapping"

This tag establishes the relationship, if any, between color channels and alpha (and/or pre-multiplied) alpha channels. Each element of array specifies number of alpha channel associated with regular (color) channel. Zero or negative value means absence of alpha mapping for particular color channel. For example:

"AlphaMapping" with {1, 1, 1, -1} as value means that all red, green and blue channels of image are mapped to single (first) alpha channel, which available under 0-index for current image through ImageGear API. {-1, 2, 1, -1} value means availability of two different alpha channels for green and blue channels and absence of alpha channel for red channel.

Additional information about available alpha channels can be accessed through "Alpha1", "Alpha2", "Alpha3" and "Alpha4" tags.

"Alpha1", "Alpha2", "Alpha3", "Alpha4"

Each of these tags represents information about alpha channels. Valid value for each tag is array with three integer elements. First element represents index of codestream (-1 or non-negative value), in which alpha channel is (or "should be" in case of write) resided. Second - index of component in which alpha is stored (-1 or non-negative value). Last element specifies whether alpha is regular (0) or pre-multiplied (1). For example:

"Alpha1" with {0, 3, 0} as value means that first alpha channel is regular and located in fourth component of the first codestream. {1, 0, 1} value represents pre-multiplied alpha in first component of second codestream in JPX layer.

"XML"

This tag serves for getting and setting some specific information written in XML language. Please note that only JPEG 2000 format is able to store XML data. It must be set as a text string.

"IPR"

This tag serves for getting and setting IPR (Intellectual Property Rights) information. The IPR metadata defines metadata to either protect the rights of the owner of the image or provide further information to request permission to use it. It is important for developers and users to properly protect the rights of the owner of the image data.

Please note that only JPEG 2000 format is able to store IPR data. It must be set as a text string.

"Format"

This tag serves for getting the format of the JPEG 2000 file. Its possible values are:

"Compression"

This tag serves for getting a compression type of the JPEG 2000 image. Its possible values are:

JPEG2K sets one of these values depending on the type of the image. This tag is not used in JPEG2K writing.

"Resolution"

This tag serves for getting the resolution information of JPEG 2000 image. It contains four fields of type double that specify resolution values, in pixels per meter:

If neither Capture nor Display resolution is present in the image the corresponding fields are set to 0.0

Comments

JPEG 2000 standard defines a compression scheme and a file format for interchange of JPEG 2000 compressed data.

The compression scheme is based on a discrete wavelet transform, and supports both lossy and lossless modes. JPEG 2000 compression is similar to JPEG in that it supports lossy compression. However, JPEG 2000 allows achieving much higher compression ratios while preserving good image quality.

JPEG 2000 file format defines a basic set of features that allow interchange of JPEG 2000 compressed images.

Metadata Update

You can use the Metadata Update API to update XML, IPR, Comment and Resolution metadata in JPEG 2000 files. You can also use the Metadata Update API to update Comment metadata in JPEG 2000 code stream files. Metadata Update API can only change a single occurrence of the Comment metadata.

Capture and Display Resolutions are represented by their X and Y values that can only be updated together. An attempt to update only X or Y value leaving the other value to 0 will result in no change at all.

 

 

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