| Filter Control Parameter |
Type |
Default Value |
Available Values |
Description |
| CODE_BLOCK_SIZE |
Long |
64 |
4, 8, 16, 32, 64 |
Affects image saving. Nominal code-block dimension. The actual dimension is subject to precinct, tile, and image dimensions. |
| CODE_BLOCK_STYLE |
Long |
IG_JPEG2K_CODE_BLOCK_STYLE_ALL_OFF = 0 |
enumJPEG2KCodeBlockStyles Enumeration values. |
Affects image saving. Block coder mode switches. Any combination of values from enumJPEG2KCodeBlockStyles Enumeration is legal. |
| DISCARD_LEVELS |
Long |
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 DISCARD_LEVELS = 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 WAVELET_LEVELS parameter to specify the number of DWT levels for JPEG 2000 image saving. |
| DISPLAY_OPTIMIZED |
Boolean |
False |
False, True |
Affects image loading. This parameter forces the filter to convert the images to RGB24 format during the loading, regardless of the original color space, alpha channels, and bit depth. This may result in faster display of the image, because no color space conversions will be used during display. Note that setting this parameter to True may result in slower image loading, because of the additional conversion applied to rasters during the loading. |
| EBCOT_BITPLANE_SHIFT |
Long |
0 |
0, 3 |
This control parameter should be used in combination with the CODE_BLOCK_STYLE control parameter. Setting EBCOT_BITPLANE_SHIFT to 3 and CODE_BLOCK_STYLE to IG_JPEG2K_CODE_BLOCK_STYLE_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. |
| FILE_FORMAT |
Long |
IG_JPEG2K_FORMAT_JP2 = 1 |
enumJPEG2KFormat Enumeration values. |
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. |
| ICC_PROFILE_MODE |
Long |
JPEG2K_ICC_PROFILE_LOAD = 0 |
enumJPEG2KICCProfileModes Enumeration values. |
Specifies the usage mode for ICC profiles embedded into JPX images. |
| LOAD_COMPOSITION |
Boolean |
False |
False |
This parameter is reserved for future use. Set to False. |
| MODE |
Long |
0 |
0 |
This parameter has been deprecated. Set to 0. |
| PROGRESSION_ORDER |
Long |
IG_JPEG2K_PROGRESSION_ORDER_LRCP = 0 |
enumJPEG2KProgressionOrders Enumeration values. |
Affects image saving. This parameter specifies the progression order to be used by the result file. See enumJPEG2KProgressionOrders Enumeration for available progression orders. |
| QUALITY_LAYERS |
Array of Double |
NULL |
NULL or array of non-negative Double numbers. |
Affects image saving. This parameter represents a more powerful version of the RATE_BYTES 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.
 |
If some entries of the QUALITY_LAYERS array are very close to each other, and the image is not big, the corresponding quality layers may end up containing no image data.
ImageGear skips creation of empty quality layers. This has no impact on the saved image quality, but slightly reduces the coding time and the saved file size. Example:
Dim format As
IGFormatParams
Dim parameter As
IGControlParameter
Set format =
frmMain.IGFormatsCtl
1.Settings.GetFormat
Ref(IG_FORMAT_JPEG2K
)
Set parameter =
format.GetParamCopy(
"QUALITY_LAYERS")
parameter.value.Arra
y.ChangeAttrs
IG_DATA_DOUBLE, 3
parameter.value.Arra
y.Double(0) = 0.01
parameter.value.Arra
y.Double(1) = 0.1
parameter.value.Arra
y.Double(2) = 0.5
format.UpdateParamFr
om parameter
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 code stream): 480000 * 0.5 / 8 = 30000 bytes
|
|
| QUANT_STEP |
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. |
| RATE_BYTES |
Long |
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 different compression rates. 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 QUALITY_LAYERS control parameter which uses relative coefficients.
|
|
| RESOLUTION_MODE |
Long |
IG_JPEG2K_RESOLUTION_MODE_PREFER_DISPLAY = 0 |
enumJPEG2KResolutionModes Enumeration |
This control parameter specifies the mapping between JPEG 2000 Capture and Display resolutions and ImageGear DIB resolution. JPEG 2000 format allows storing two sets of resolution information: Capture Resolution and Display Resolution. ImageGear keeps only one set of resolution information for an image. This parameter specifies which resolution from JPEG 2000 image to use as ImageGear DIB resolution, and how to save ImageGear resolution to a JPEG 2000 image. ImageGear also passes both Capture and Display resolutions to the user as metadata values, regardless of the RESOLUTION_MODE parameter.
|
The library allows you to save no resolution information, Display Resolution only, or both Display and Capture resolution. It does not allow saving Capture Resolution without saving Display Resolution. If Capture Resolution is known at the time of saving, but Display resolution is not known, the library writes equal values for Display and Capture resolutions.
|
|
| STITCH_TILES |
Boolean |
True |
False, True |
Affects image loading. Set this parameter to False to allow:
Otherwise, these methods behave as if the image is not tiled.
|
| SAVE_VERSION_INFO |
Boolean |
True |
False, True |
Affects image saving and metadata updating. Unless disabled by setting this parameter to False, ImageGear always inserts its own UUID box with version information into JP2 and JPX files being saved.
|
It is recommended that you do not disable writing the version information, as it could provide helpful hints for future decoders.
|
|
| TILE_HEIGHT |
Long |
0 |
Any non-negative integer value. |
Affects image saving. Specifies the height of one tile in the reference grid. A zero value indicates the image's height. |
| TILE_WIDTH |
Long |
0 |
Any non-negative integer value. |
Affects image saving. Specifies the width of one tile in reference grid. A zero value indicates the image's width. |
| VIEW_HEIGHT |
Long |
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 DISCARD_LEVELS in that it allows you to select the highest resolution level for image loading. |
| VIEW_WIDTH |
Long |
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 DISCARD_LEVELS in that it allows you to select the highest resolution level for image loading. |
| WAVELET_FILTER |
Long |
IG_JPEG2K_FILTER_AUTO = -1 |
enumJPEG2KFilters |
Affects image saving. Specifies the type of Wavelet filter (Auto, Reversible, or Irreversible) to be used for Discrete Wavelet Transform.
|
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.
|
|
| WAVELET_LEVELS |
AT_INT32 |
-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. |
