Package com.pdftools.optimization

Class ImageRecompressionOptions

java.lang.Object

com.pdftools.internal.NativeBase

com.pdftools.internal.NativeObject

com.pdftools.optimization.ImageRecompressionOptions

public class ImageRecompressionOptions
extends NativeObject

The parameters for image recompression

Method Summary

Modifier and Type	Method	Description
CompressionAlgorithmSelection	getAlgorithmSelection()	The strategy for image recompression (Getter)
double	getCompressionQuality()	The compression quality for lossy image compression algorithms (Getter)
boolean	getReduceColorComplexity()	Enable color complexity reduction.
void	setAlgorithmSelection(CompressionAlgorithmSelection value)	The strategy for image recompression (Setter)
void	setCompressionQuality(double value)	The compression quality for lossy image compression algorithms (Setter)
void	setReduceColorComplexity(boolean value)	Enable color complexity reduction.

Methods inherited from class com.pdftools.internal.NativeObject

equals, hashCode

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, toString, wait, wait, wait

Method Details

getAlgorithmSelection

public CompressionAlgorithmSelection getAlgorithmSelection()

The strategy for image recompression (Getter)

For each image to be recompressed, a specific choice of compression algorithms are tried. The selection of algorithms depends on this strategy, the type of the optimizer profile (e.g. profiles.Web), the color space of the image, and getCompressionQuality(). The image is recompressed using the algorithm resulting in the smallest output file.

Refer to CompressionAlgorithmSelection for more information on strategies.

Default:

• profiles.Web profile: CompressionAlgorithmSelection.BALANCED
• profiles.Print profile: CompressionAlgorithmSelection.PRESERVE_QUALITY
• profiles.Archive profile: CompressionAlgorithmSelection.PRESERVE_QUALITY
• profiles.MinimalFileSize profile: CompressionAlgorithmSelection.BALANCED
• profiles.Mrc profile: CompressionAlgorithmSelection.BALANCED

setAlgorithmSelection

public void setAlgorithmSelection(CompressionAlgorithmSelection value)

The strategy for image recompression (Setter)

For each image to be recompressed, a specific choice of compression algorithms are tried. The selection of algorithms depends on this strategy, the type of the optimizer profile (e.g. profiles.Web), the color space of the image, and getCompressionQuality(). The image is recompressed using the algorithm resulting in the smallest output file.

Refer to CompressionAlgorithmSelection for more information on strategies.

Default:

• profiles.Web profile: CompressionAlgorithmSelection.BALANCED
• profiles.Print profile: CompressionAlgorithmSelection.PRESERVE_QUALITY
• profiles.Archive profile: CompressionAlgorithmSelection.PRESERVE_QUALITY
• profiles.MinimalFileSize profile: CompressionAlgorithmSelection.BALANCED
• profiles.Mrc profile: CompressionAlgorithmSelection.BALANCED

Throws:

IllegalArgumentException - if value is null

getCompressionQuality

public double getCompressionQuality()

The compression quality for lossy image compression algorithms (Getter)

This property specifies the compression quality for the JPEG and JPEG2000 image compression algorithms. Valid values are between 0 (lowest quality) and 1 (highest quality).

Although the JBIG2 algorithm for bi-tonal images also allows lossy compression, it is not influenced by this property. The JBIG2 compression quality is fixed at 1 (lossless).

Default:

• profiles.Web profile: 0.8
• profiles.Print profile: 0.9
• profiles.Archive profile: 0.9
• profiles.MinimalFileSize profile: 0.75
• profiles.Mrc profile: 0.75

setCompressionQuality

public void setCompressionQuality(double value)

The compression quality for lossy image compression algorithms (Setter)

This property specifies the compression quality for the JPEG and JPEG2000 image compression algorithms. Valid values are between 0 (lowest quality) and 1 (highest quality).

Although the JBIG2 algorithm for bi-tonal images also allows lossy compression, it is not influenced by this property. The JBIG2 compression quality is fixed at 1 (lossless).

Default:

• profiles.Web profile: 0.8
• profiles.Print profile: 0.9
• profiles.Archive profile: 0.9
• profiles.MinimalFileSize profile: 0.75
• profiles.Mrc profile: 0.75

Throws:

IllegalArgumentException - If the given value is outside of the range 0 - 1

getReduceColorComplexity

public boolean getReduceColorComplexity()

Enable color complexity reduction. (Getter)

When enabled, the software analyzes images that utilize device color spaces (DeviceRGB, DeviceCMYK, or DeviceGray) as well as indexed images with a device color space as their base. If applicable, the images are converted according to the following criteria:

• Images in DeviceRGB or DeviceCMYK color space where all pixels are gray will be converted to grayscale using the DeviceGray color space.
• Images containing only black and white pixels will be converted to bitonal images.
• Images where all pixels are of the same color will be downsampled to a single pixel.

Additionally, image masks and soft masks are optimized in the following ways:

• Soft masks consisting only of black and white pixels will be converted into a standard mask.
• Any (soft) mask that is completely opaque will be removed.

Default:

• profiles.Web profile: true
• profiles.Print profile: true
• profiles.Archive profile: true
• profiles.MinimalFileSize profile: true
• profiles.Mrc profile: false

setReduceColorComplexity

public void setReduceColorComplexity(boolean value)

Enable color complexity reduction. (Setter)

When enabled, the software analyzes images that utilize device color spaces (DeviceRGB, DeviceCMYK, or DeviceGray) as well as indexed images with a device color space as their base. If applicable, the images are converted according to the following criteria:

• Images in DeviceRGB or DeviceCMYK color space where all pixels are gray will be converted to grayscale using the DeviceGray color space.
• Images containing only black and white pixels will be converted to bitonal images.
• Images where all pixels are of the same color will be downsampled to a single pixel.

Additionally, image masks and soft masks are optimized in the following ways:

• Soft masks consisting only of black and white pixels will be converted into a standard mask.
• Any (soft) mask that is completely opaque will be removed.

Default:

• profiles.Web profile: true
• profiles.Print profile: true
• profiles.Archive profile: true
• profiles.MinimalFileSize profile: true
• profiles.Mrc profile: false