Using image resources

Soft image resources can be stored in the page segment library or object container library, can be included through an Include Object (IOB) structured field, and are embedded in the data stream at print time. PSF looks for a soft image resource in this order:

1. Inline in the print data
2. In a user library
3. In the system page segment library
4. In the system object container resource library

If you use the image resource in more than a single page of the document or in multiple documents, it might be better to use the MDR structured field to identify the image resource as a hard resource in the print data set. By using the MDR structured field, PSF can download the image resource once and use it repeatedly in the print data set. If the image resource is being used as a hard resource, it must be stored in the object container library. PSF looks for a hard image resource object in this order:

1. Inline in the print data set
2. In a user library
3. In the system object container library

Because an image resource is one type of resource in a library of multiple resource types, and PSF does not enforce a prefix for the 8-character name of the image resource, your site can define a naming convention to avoid conflicts with other resources. IBM® recommends a prefix of I1 for image resources.

The image resource can be included in a print data set, in an overlay resource, in a page segment resource, or stored and used as a resource. An image resource can be manipulated in these ways:

• It can be placed in any position on the page.
• It can be stored and transmitted to the printer in compressed form, saving storage and transmission time.
• It can be resolution-independent, so that an image created with one resolution (pel density) can be printed at the same size on a printer with a different resolution.
• It can be scaled to any size (enlarged or reduced) by the printer.
• It can be rotated by the printer.
• It can be clipped so that only part of it is printed.

For more information about coding IOCA image data objects and the options you can specify, see Mixed Object Document Content Architecture Reference, AFPC-0004 or to Image Object Content Architecture Reference, AFPC-0003.

PSF provides a MO:DCA-P document called IOCAMMR. IOCAMMR contains an IOCA image that is compressed by the IBM MMR compression algorithm. You can print this image on any IPDS printer that supports IOCA. You can also use this document as a test file or print it in hexadecimal to assist an image application developer in understanding the structure of a MO:DCA-P document that contains an IOCA image object. If an image is compressed by use of the CCITT Group4 compression algorithm, you would code it similarly.