(Optional; PDF 1.3) An array of alternate image dictionaries for this image. The order of elements within the array has no significance. This entry may not be present in an image XObject that is itself an alternate image.

(Required except for image masks and images that use the JPXDecode filter) 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, 8, and (in PDF 1.5) 16. If ImageMask is true, this entry is optional, and if specified, its value must be 1. If the image stream uses a filter, the value of BitsPerComponent must be consistent with the size of the data samples that the filter delivers. In particular, a CCITTFaxDecode or JBIG2Decode filter always delivers 1-bit samples, a RunLengthDecode or DCTDecode filter delivers 8-bit samples, and an LZWDecode or FlateDecode filter delivers samples of a specified size if a predictor function is used. If the image stream uses the JPXDecode filter, this entry is optional and ignored if present. The bit depth is determined in the process of decoding the JPEG2000 image.

(Required for images, except those that use the JPXDecode filter; not allowed for image masks) The color space in which image samples are specified; it can be any type of color space except Pattern. If the image uses the JPXDecode filter, this entry is optional: • If ColorSpace is present, any color space specifications in the JPEG2000 data are ignored. • If ColorSpace is absent, the color space specifications in the JPEG2000 data are used. The Decode array is also ignored unless ImageMask is true.

(Optional) An array of numbers describing how to map image samples into the range of values appropriate for the image’s color space. If ImageMask is true, the array must be either [0 1] or [1 0]; otherwise, its length must be twice the number of color components required by ColorSpace. If the image uses the JPXDecode filter and ImageMask is false, Decode is ignored. Default value: see “Decode Arrays”.

(Required) The height of the image, in samples.

(Optional; PDF 1.3; indirect reference preferred) The digital identifier of the image’s parent Web Capture content set.

(Optional) A flag indicating whether the image is to be treated as an image mask. If this flag is true, the value of BitsPerComponent must be 1 and Mask and ColorSpace should not be specified; unmasked areas are painted using the current nonstroking color. Default value: false.

(Optional; PDF 1.1) The name of a color rendering intent to be used in rendering the image. Default value: the current rendering intent in the graphics state.

(Optional) A flag indicating whether image interpolation is to be performed. Default value: false.

(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, or an array specifying a range of colors to be applied to it as a color key mask. If ImageMask is true, this entry must not be present.

(Optional; PDF 1.4) A metadata stream containing metadata for the image.

(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.

(Optional; PDF 1.5) An optional content group or optional content membership dictionary, specifying the optional content properties for this image XObject. Before the image is processed, its visibility is determined based on this entry. If it is determined to be invisible, the entire image is skipped, as if there were no Do operator to invoke it.

(Optional; PDF 1.2) An OPI version dictionary for the image. If ImageMask is true, this entry is ignored.

(Optional; PDF 1.4) A subsidiary image XObject defining a soft-mask image to 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 are interpreted as shape or opacity. If present, this entry overrides 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 — remain in effect.) If SMask is absent, the image has no associated soft mask (although the current soft mask in the graphics state may still apply).

(Optional for images that use the JPXDecode filter, meaningless otherwise; PDF 1.5) A code specifying how soft-mask information encoded with image samples should be used: 0 If present, encoded soft-mask image information should be ignored. 1 The image’s data stream includes encoded soft-mask values. An application can 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 color channels that have been preblended with a background; the image data also includes an opacity channel. An application can 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 should not be specified. Default value: 0.

(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.

(Required) The type of XObject that this dictionary describes; must be Image for an image XObject.

(Optional) The type of PDF object that this dictionary describes; if present, must be XObject for an image XObject.

(Required) The width of the image, in samples.