Offending command: sethalftone

The ‘Sethalftone’ command is used for the handling of screenrulings. There are quite a number of things that can cause this kind of error.

Insufficient memory
Sethalftone errors can also be caused by insufficient free space on the harddisk of the RIP. Funnily enough this can be more of a problem when you try to output very coarse screenrulings like 5 lines per inch. This can cause “limitcheck” errors, offending command “sethalftone” because the RIP needs too much memory to calculate all the screentiles for such large dots.

There are several workarounds for this kind of problem:

• Lower the resolution of the RIP
• Allow the RIP to use more memory. This is often easy on software RIPs that run on Macs.
• Try cleaning up the RIP a bit to solve the error.
• The following PostScript code may solve the problem on Agfa hardware RIPs. Simply download the code to the RIP. It enlarges internal buffers. I do not know whether this code is still valid for current RIPs. The number 20000000 in the code represents the size of the cache in bytes. You can modify this value.

true 0 startjob

<< /MaxScreenItem 20000000 >> setuserparams

<< /MaxScreenStorage 20000000 >> setsystemparams

Updating Preps
Shlomit Heymann wrote to me that she got around a PostScript error: typecheck; Offending Command:sethalftone when outputting CMYK PostScript files to a Harlequin Rip version 4.5 by updating Preps from version 4.0 to version 4.04.

Corrupt software on the RIP
At one of our sites, a ‘Sethalftone’ error was caused by corrupted screenfilter software on a Star 800 RIP. Simply reinstalling all of the RIP’s bootfiles solved the error.

Using PhotoShop as a workaround
Since “sethalftone” errors only occur when the Rip has to rasterize a page, it is sometimes possible to use the “Rasterize” filter of PhotoShop to rasterize elements of the page, instead of relying on the RIP to handle all the work.

Incorrect configuration of the RIP
When using several 16-bit Agfa Balanced Screens or several halftone screens from the Agfa Balanced Screening Option Kit (Flexo, Gravure, etc.) on an Agfa Taipan 2.02 or 3.01 a PostScript error “limitcheck”, offending command “sethalftone” may occur. This problem can be solved by changing some buffer settings in the Taipan Tuner application.