Package com.pdf_tools.fourheights.pdftoolbox.pdf.content

Class Image

java.lang.Object

com.pdf_tools.fourheights.pdftoolbox.internal.NativeBase

com.pdf_tools.fourheights.pdftoolbox.internal.NativeObject

com.pdf_tools.fourheights.pdftoolbox.pdf.content.Image

public class Image
extends NativeObject

Method Summary

Modifier and Type	Method	Description
static Image	create(Document targetDocument, Stream stream)	Create an image object from image data.
void	extract(Stream stream)	Extract embedded image from PDF
void	extract(Stream stream, ImageType imageType)	Extract embedded image from PDF
int	getBitsPerComponent()	the number of bits per component.
ColorSpace	getColorSpace()	the color space in which image samples are specified.
ImageType	getDefaultImageType()	Default extracted image type.
byte[]	getSamples()	The raw content of the image.
Size	getSize()	The size of the image in samples.

Methods inherited from class com.pdf_tools.fourheights.pdftoolbox.internal.NativeObject

equals, hashCode

Methods inherited from class java.lang.Object

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

Method Detail

create

public static Image create(Document targetDocument,
                           Stream stream)
                    throws java.io.IOException,
                           UnknownFormatException,
                           CorruptException

Create an image object from image data.

Supported formats are:

• BMP
• DIB
• JPEG
• JPEG2000
• JBIG2
• PNG
• GIF

The returned image object is not yet painted on any page, but it is associated with the given target document.

Parameters:

targetDocument - the output document with which the returned object is associated

stream - the image data stream

Returns:

the newly created image object

Throws:

java.io.IOException - Error reading from the image or writing to the document

UnknownFormatException - The image data has an unknown format

CorruptException - The image data is corrupt

java.lang.IllegalArgumentException - if the targetDocument argument has already been closed

java.lang.IllegalArgumentException - if the targetDocument argument is read-only

java.lang.IllegalArgumentException - if the stream argument is null

java.lang.IllegalArgumentException - if targetDocument is null

java.lang.IllegalArgumentException - if stream is null

extract

public void extract(Stream stream)
             throws GenericException

Extract embedded image from PDF

Facilitate the extraction of images from a specified page within a PDF, outputting them in the imageType format.

By default, the method determines the format of the extracted image based on the embedded image data present within the PDF. Users can ascertain the default image format through getDefaultImageType(). It's important to note that not all image types or conversion processes are universally supported, hence adhering to the default ImageType is advisable for optimal compatibility.

Key considerations include:

• The extraction process isolates the image from the page's resources, neglecting any contextual attributes from the PDF page. Consequently, the original resolution and modifications—such as scaling, rotation, or cropping—that influence the image's appearance on the page are not preserved in the extracted image.
• In instances where a GenericException error arises, the output file may be compromised and rendered unusable.

This method is designed to efficiently retrieve images without their page-specific modifications, ensuring a straightforward extraction process.

Parameters:

stream - The image data stream.

Throws:

java.lang.IllegalArgumentException - if the stream argument is null

java.lang.IllegalStateException - if the image has already been closed

GenericException - if image extraction fails

java.lang.IllegalArgumentException - if stream is null

extract

public void extract(Stream stream,
                    ImageType imageType)
             throws GenericException

Extract embedded image from PDF

Facilitate the extraction of images from a specified page within a PDF, outputting them in the imageType format.

By default, the method determines the format of the extracted image based on the embedded image data present within the PDF. Users can ascertain the default image format through getDefaultImageType(). It's important to note that not all image types or conversion processes are universally supported, hence adhering to the default ImageType is advisable for optimal compatibility.

Key considerations include:

• The extraction process isolates the image from the page's resources, neglecting any contextual attributes from the PDF page. Consequently, the original resolution and modifications—such as scaling, rotation, or cropping—that influence the image's appearance on the page are not preserved in the extracted image.
• In instances where a GenericException error arises, the output file may be compromised and rendered unusable.

This method is designed to efficiently retrieve images without their page-specific modifications, ensuring a straightforward extraction process.

Parameters:

stream - The image data stream.

imageType - The desired image type of the extracted image stream. If the embedded image data cannot be directly extracted to the chosen ImageType, the data is first recompressed and then extracted to the chosen ImageType. In this case, extraction is slower and there can be some loss of image quality. The default image type can be retrieved by calling getDefaultImageType().

Throws:

java.lang.IllegalArgumentException - if the stream argument is null

java.lang.IllegalStateException - if the image has already been closed

GenericException - if image extraction fails

java.lang.IllegalArgumentException - if stream is null

getDefaultImageType

public ImageType getDefaultImageType()

Default extracted image type. (Getter)

The default image type that will be extracted, based on the way that the image data is compressed and stored in the PDF file. The type of the output image is ImageType.JPEG for embedded JPEG and JPEG2000 images. In all other cases the image type will be ImageType.TIFF.

Throws:

java.lang.IllegalStateException - if the image has already been closed

getSize

public Size getSize()

The size of the image in samples. (Getter)

Samples are often also called pixels.

Throws:

java.lang.IllegalStateException - if the image has already been closed

getSamples

public byte[] getSamples()

The raw content of the image. (Getter)

The samples (pixels) are given in order, top to bottom, left to right. Each sample is given component by component. There is no padding between components or samples, except that each row of sample data begins on a byte boundary. If the number of data bits per row is not a multiple of 8, the end of the row is padded with extra bits to fill out the last byte. Padding bits should be ignored.

Most often, each component is 8 bits, so there's no packing/unpacking or alignment/padding. Components with 2 or 4 bits are very rare.

If the image is compressed, it will be decompressed in order to get the samples. For very large images, this may take some time.

Throws:

java.lang.IllegalStateException - if the image has already been closed

getBitsPerComponent

public int getBitsPerComponent()

the number of bits per component. (Getter)

The number of bits used to represent each color component. Only a single value may be specified; the number of bits is the same for all color components. Valid values are 1, 2, 4, and 8.

Throws:

java.lang.IllegalStateException - if the image has already been closed

getColorSpace

public ColorSpace getColorSpace()

the color space in which image samples are specified. (Getter)

Throws:

java.lang.IllegalStateException - if the image has already been closed