Key |
Type |
Value |
---|---|---|
Type |
name |
(Optional) The type of PDF object that this dictionary describes; if present, shall be XObject for an image XObject. |
Subtype |
name |
(Required) The type of XObject that this dictionary describes; shall be Image for an image XObject. |
Width |
integer |
(Required) The width of the image, in samples. |
Height |
integer |
(Required) The height of the image, in samples. |
ColorSpace |
name or array |
(Required for images, except those that use the JPXDecode filter; not allowed forbidden for image masks) The colour space in which image samples shall be specified; it can be any type of colour space except Pattern. If the image uses the JPXDecode filter, this entry may be present: •If ColorSpace is present, any colour space specifications in the JPEG2000 data shall be ignored. •If ColorSpace is absent, the colour space specifications in the JPEG2000 data shall be used. The Decode array shall also be ignored unless ImageMask is true. |
BitsPerComponent |
integer |
(Required except for image masks and images that use the JPXDecode filter) The number of bits used to represent each colour component. Only a single value shall be specified; the number of bits shall be the same for all colour components. The value shall be 1, 2, 4, 8, or (in PDF 1.5) 16. If ImageMask is true, this entry is optional, but if specified, its value shall be 1. If the image stream uses a filter, the value of BitsPerComponentshall be consistent with the size of the data samples that the filter delivers. In particular, a CCITTFaxDecode or JBIG2Decode filter shall always deliver 1-bit samples, a RunLengthDecode or DCTDecode filter shall always deliver 8-bit samples, and an LZWDecode or FlateDecode filter shall deliver samples of a specified size if a predictor function is used. If the image stream uses the JPXDecode filter, this entry is optional and shall be ignored if present. The bit depth is determined by the conforming reader in the process of decoding the JPEG2000 image. |
Intent |
name |
(Optional; PDF 1.1) The name of a colour rendering intent to be used in rendering the image (see 8.6.5.8, "Rendering Intents" ). Default value: the current rendering intent in the graphics state. |
ImageMask |
boolean |
(Optional) A flag indicating whether the image shall be treated as an image mask (see 8.9.6, "Masked Images" ). If this flag is true, the value of BitsPerComponent shall be 1 and Mask and ColorSpace shall not be specified; unmasked areas shall bepainted using the current nonstroking colour. Default value: false. |
Mask |
stream or array |
(Optional except for image masks; not allowed for image masks; PDF 1.3) An image XObject defining an image mask to be applied to this image (see 8.9.6.3, "Explicit Masking" ), or an array specifying a range of colours to be applied to it as a colour key mask (see 8.9.6.4, "Colour Key Masking" ). If ImageMask is true, this entry shall not be present. |
Decode |
array |
(Optional) An array of numbers describing how to map image samples into the range of values appropriate for the image’s colour space (see 8.9.5.2, "Decode Arrays" ). If ImageMask is true, the array shall be either [ 0 1 ] or [ 1 0 ]; otherwise, its length shall betwice the number of colour components required by ColorSpace. If the image uses the JPXDecode filter and ImageMask is false, Decode shall be ignored by a conforming reader. Default value: see 8.9.5.2, "Decode Arrays" . |
Interpolate |
boolean |
(Optional) A flag indicating whether image interpolation shall beperformed by a conforming reader (see 8.9.5.3, "Image Interpolation" ). Default value: false. |
Alternates |
array |
(Optional; PDF 1.3) An array of alternate image dictionaries for this image (see 8.9.5.4, "Alternate Images" ). The order of elements within the array shall have no significance. This entry shall not bepresent in an image XObject that is itself an alternate image. |
SMask |
stream |
(Optional; PDF 1.4) A subsidiary image XObject defining a soft-mask image (see 11.6.5.3, "Soft-Mask Images" ) that shall be used as a source of mask shape or mask opacity values in the transparent imaging model. The alpha source parameter in the graphics state determines whether the mask values shall beinterpreted as shape or opacity. If present, this entry shall override the current soft mask in the graphics state, as well as the image’s Mask entry, if any. However, the other transparency-related graphics state parameters—blend mode and alpha constant—shall remain in effect. If SMask is absent, the image shall have no associated soft mask (although the current soft mask in the graphics state may still apply). |
SMaskInData |
integer |
(Optional for images that use the JPXDecode filter, meaningless otherwise; PDF 1.5) A code specifying how soft-mask information (see 11.6.5.3, "Soft-Mask Images" ) encoded with image samples shall be used: 0 If present, encoded soft-mask image information shall beignored. 1 The image’s data stream includes encoded soft-mask values. Aconforming reader may create a soft-mask image from the information to be used as a source of mask shape or mask opacity in the transparency imaging model. 2 The image’s data stream includes colour channels that have been preblended with a background; the image data also includes an opacity channel. A conforming reader may create a soft-mask image with a Matte entry from the opacity channel information to be used as a source of mask shape or mask opacity in the transparency model. If this entry has a nonzero value, SMask shall not be specified. See also 7.4.9, "JPXDecode Filter" . Default value: 0. |
Name |
name |
(Required in PDF 1.0; optional otherwise) The name by which this image XObject is referenced in the XObject subdictionary of the current resource dictionary (see 7.8.3, "Resource Dictionaries" ). This entry is obsolescent and shall no longer be used. |
StructParent |
integer |
(Required if the image is a structural content item; PDF 1.3) The integer key of the image’s entry in the structural parent tree (see 14.7.4.4, "Finding Structure Elements from Content Items" ). |
ID |
byte string |
(Optional; PDF 1.3; indirect reference preferred) The digital identifier of the image’s parent Web Capture content set (see 14.10.6, "Object Attributes Related to Web Capture" ). |
OPI |
dictionary |
(Optional; PDF 1.2) An OPI version dictionary for the image; see 14.11.7, "Open Prepress Interface (OPI)" . If ImageMask is true, this entry shall be ignored. |
Metadata |
stream |
(Optional; PDF 1.4) A metadata stream containing metadata for the image (see 14.3.2, "Metadata Streams" ). |
OC |
dictionary |
(Optional; PDF 1.5) An optional content group or optional content membership dictionary (see 8.11, "Optional Content" ), specifying the optional content properties for this image XObject. Before the image is processed by a conforming reader, its visibility shall bedetermined based on this entry. If it is determined to be invisible, the entire image shall be skipped, as if there were no Do operator to invoke it. |