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Unformatted text preview: Edited by Foxit Reader Copyright(C) by Foxit Software Company,2005-2007 For Evaluation Only. POSTSCRIPT
PostScript is a page description language. It has become a "DEFACTO STANDARD" in our industry. It was originally designed by Adobe in the early 1980's for Apple Computer as a language to drive their new printer (laser) Virtually all Programs used on Personal Computers in our industry are "PostScript Compatible" ( write to a Postscript file). Virtually all high-end Printing Devices (Laser Printers, Proofing Devices, Imagesetters, etc.) are "PostScript Compatible" (Their RIPs can read PostScript). SELECT PRINT Quark File RIP LASER PRINTER SELECT PRINT PageMaker File Produce a Postscript File RIP EPSON 5000 SELECT PRINT Illustrator File RIP 9800 IMAGESETTER CGRA 013 - INTRODUCTION TO ELECTRONIC PREPRESS Page 1 of 8 Edited by Foxit Reader Copyright(C) by Foxit Software Company,2005-2007 For Evaluation Only. PostScript acts as an interim step such that all original files can be read by printing devices. PostScript is Vector Based, and must be rasterized prior to output. RIPS (Raster Image Processors) are computer that run a PostScript interpreter software which can read PostScript code and generate Raster Data (Output Device). The following steps outline the different relationships and processes involved in a PostScript Workflow. Step 1 - Application Program Original Quark file. This is a proprietary file format that describes boxes, text, etc. using vector commands. Imported graphics are bitmapped (raster) files that are linked or embedded in the Quark file. (bitmap) used by the imagesetter Step 2 - Print Command This instructs Quark to generate a PS file from the Quark Code. Attributes of the PostScript file are determined by the setting you select in Quark (e.g. pre-separated or composite). CGRA 013 - INTRODUCTION TO ELECTRONIC PREPRESS Page 2 of 8 Edited by Foxit Reader Copyright(C) by Foxit Software Company,2005-2007 For Evaluation Only. Step 3 - PostScript File Created This file contains standardized PostScript Code that can be understood by all PostScript Compatible Output device RIPs Step 4 - RIP The RIP interpreter reads the Postscript Raster File and generates Data in the output device's proprietary format. Step 5 - Outputting The output device uses the raster data which controls the imaging head to produce the image on paper film, plate, etc. Output Raster Resolution determined by Quark print menu or the Job Ticket CGRA 013 - INTRODUCTION TO ELECTRONIC PREPRESS Page 3 of 8 Edited by Foxit Reader Copyright(C) by Foxit Software Company,2005-2007 For Evaluation Only. Generating PostScript
Step 1 - Select Print Driver In the Chooser on the Mac, select the correct driver. Laserwriter 8.x (Apple) PS Driver (Adobe) The print driver provides instructions operating system file code. Step 2 - Set up PPD PPD: PostScript Print Description File The PPD holds the unique characteristices of a specific output device, and builds these characteristics into each Postscript file created. These include: Paper size Available
not device independent at this to the computer's to generate PS code from the application Resolution Screening - dot shape, line ruling, etc. Note: The PostScript file is point. Step 3 - Select PostScript Level PS Levels I, II, and III. PostScript Level II has expanded capabilities over level I: can handle compressed improved screening
CGRA 013 - INTRODUCTION TO ELECTRONIC PREPRESS embedded graphics "supercell" less moire
Page 4 of 8 Edited by Foxit Reader Copyright(C) by Foxit Software Company,2005-2007 For Evaluation Only. POSTSCRIPT LEVEL III has expanded capabilities over level II: - 16 Bit opposed to 8 Bit Blends - PDF Workflow & Extreme architecture (Apogee) - In RIP functionality (e.g. imposition) Sending PS files to the RIP with attributes that can't be handled by the RIP will cause the RIP to crash e.g. sending JPEG files to a Level I RIP PostScript RIPs are downward compatible, but not upward i.e. PS Level III rip can read Level I, but not vice versa COMPOSITE VS SEPARATED PS Composite - all colour information is in a single file Separated - Within the PS each colour has an identifiable file Older workflows employed separated Postscript - the RIP simply rasterized & screened the preseparated PS Newer workflows are usually composite must be broken into its component colour + PMS 185) prior to rasterizing and screening. Some programs have trouble writing good composite PS (e.g. Quark can only write PS 1 and in Composite RIPs have trouble reproducing Spot colours, Duotones & picking up Trap information. If you send a Separated PS file to a composite workflow the colour images will print black and white or the file will crash
CGRA 013 - INTRODUCTION TO ELECTRONIC PREPRESS Page 5 of 8 - the colour info (e.g. CMYK Edited by Foxit Reader Copyright(C) by Foxit Software Company,2005-2007 For Evaluation Only. Step 4 - Create PostScript File 1. Output Direct to Printing Device - Print Driver and PPD Specific. If it sent using a different print driver TrueType, Film WRONG - Type 1 Font). Different RIPs may interpret PS differently: True Adobe RIPs vs. Clones (Harlequin) Software RIPs vs, Hardware RIPs Some programs may not write good PostScript Quark does not use Adobe DSC (Document Structure Conforming) PostScript. To create PostScript from Quark that if compatible with Preps or Trapwise, we must use the XPP Extension in Quark (Export for Prepress). Ensure the correct setting is chosen ( Separate or Composite ) in relation to the file attributes and output workflow 2. "Print to Disk" - used when a Print Server Quark File PS File
generic PS , the PS code will change and may output differently (e.g. Proof OK - wkflow is used: RIP Server Proofer Imagesetter multiple queues (e.g. line screens) sent to multiple devices frees workstations of print times better control of print functions (e.g. order of output)
CGRA 013 - INTRODUCTION TO ELECTRONIC PREPRESS Page 6 of 8 Edited by Foxit Reader Copyright(C) by Foxit Software Company,2005-2007 For Evaluation Only. PostScript and Image Management
Graphic files are generally large files and moving Quark pages with graphics embedded in them can seriously slow transfers. Image Management formats have been developed to address this problem. The concept is to have a low res image placed in Quark that is linked to a hi-res file resident on a server. This means that files are easier to manage, and print times are shorter. Examples of Image Management are: Server based OPI (Open Prepress Interface)
- Industry - Smaller PS file APR (Automatic Picture Replacement - SCITEX) The substitution takes place when the PS file is sent to the server or RIP Folder based EPS DCS (Desktop Colour Separations) 5 files - 4 Separated files (CMYK) + a Low Res Placement (free software developed by Quark) The 4 separated files are keep in a linked folder & substituted when the PS file is created Save as... (separated file) when creating PS DCS CGRA 013 - INTRODUCTION TO ELECTRONIC PREPRESS Page 7 of 8 PostScript and Image Management Workflow
PS FILE WITH LOW-RES INDICATORS QUARK FILE PRINT COMMAND LOW-RES SCANNER FILE SERVER HI-RES BROUGHT IN RIP READS PS CODE, REPLACES LOW-RES INFO WITH HI-RES DATA, AND GENERATES RASTER DATA AND SCREENS IMAGING ENGINE RASTER DATA DRIVES IMAGING HEAD CGRA 013 - INTRODUCTION TO ELECTRONIC PREPRESS Page 8 of 8 Edited by Foxit Reader Copyright(C) by Foxit Software Company,2005-2007 For Evaluation Only. Proprietary Systems
Many companies have developed proprietary (closed systems) that convert PostScript data into proprietary fonts that can be further manipulated. This was originally done to compensate for the lack of user intervention in PS Level I and II, and many companies still choose to keep their own formats even with PS level III. Some Examples of proprietary systems are: Barco & Rampage (strong Trapping abilities) DaVinci (for Retouching) Brisque (Trap & Impose Raster workflow) A generalized proprietary workflow would be as follows:
APPLICATION FILE (QUARK) PROPRIETARY SYSTEM RIP (RASTER) PS FILE PROPRIETARY FILE FORMAT (E.G. CT/LW) PREPS IMPOSITION PROPRIETARY TRAPPING OUTPUT
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This note was uploaded on 04/21/2008 for the course GCM GRA203 taught by Professor Goodyear during the Winter '08 term at Ryerson.
- Winter '08