Table 145 – Restrictions on the entries in a soft-mask image dictionary

Key

Restriction

Type

If present, shall be XObject.

Subtype

Shall be Image.

Width

If a Matte entry (see Ta b l e 146 ) is present, shall be the same as the Width value of the parent image; otherwise independent of it. Both images shall be mapped to the unit square in user space (as are all images), regardless of whether the samples coincide individually.

Height

Same considerations as for Width.

ColorSpace

Required; shall be DeviceGray.

BitsPerComponent

Required.

Intent

Ignored.

ImageMask

Shall be false or absent.

Mask

Shall be absent.

SMask

Shall be absent.

Decode

Default value: [ 0 1 ].

Interpolate

Optional.

Alternates

Ignored.

Name

Ignored.

StructParent

Ignored.

ID

Ignored.

OPI

Ignored.