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                                       354
CHAPTER 4                                                                 Graphics



FULL NAME                             ABBREVIATION

ASCIIHexDecode                        AHx

ASCII85Decode                         A85

LZWDecode                             LZW

FlateDecode (PDF 1.2)                 Fl (uppercase F, lowercase L)

RunLengthDecode                       RL

CCITTFaxDecode                        CCF

DCTDecode                             DCT

The color space specified by the ColorSpace (or CS) entry may be any of the stan-
dard device color spaces (DeviceGray, DeviceRGB, or DeviceCMYK). It may not be
a CIE-based color space or a special color space, with the exception of a limited
form of Indexed color space whose base color space is a device space and whose
color table is specified by a byte string (see “Indexed Color Spaces” on page 262).
Beginning with PDF 1.2, the value of the ColorSpace entry may also be the name
of a color space in the ColorSpace subdictionary of the current resource dictio-
nary (see Section 3.7.2, “Resource Dictionaries”). In this case, the name may des-
ignate any color space that can be used with an image XObject.

Note: The names DeviceGray, DeviceRGB, and DeviceCMYK (as well as their abbre-
viations G, RGB, and CMYK) always identify the corresponding color spaces directly;
they never refer to resources in the ColorSpace subdictionary.

The image data in an inline image may be encoded by using any of the standard
PDF filters. The bytes between the ID and EI operators are treated much the same
as a stream object’s data (see Section 3.2.7, “Stream Objects”), even though they
do not follow the standard stream syntax. (This is an exception to the usual rule
that the data in a content stream is interpreted according to the standard PDF
syntax for objects.)

Example 4.30 shows an inline image 17 samples wide by 17 high with 8 bits per
component in the DeviceRGB color space. The image has been encoded using
LZW and ASCII base-85 encoding. The cm operator is used to scale it to a width
and height of 17 units in user space and position it at coordinates (298, 388). The
q and Q operators encapsulate the cm operation to limit its effect to resizing the
image.

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