PostScript and EPS: The Languages of Professional Print Production

PostScript and EPS: The Languages of Professional Print Production

PostScript and EPS (Encapsulated PostScript) are page description languages that defined professional printing for three decades. Before PDF became dominant, PostScript was the universal language of desktop publishing and laser printers. EPS remains relevant today as the vector format of choice for importing illustrations into print-production workflows, and PostScript fluency is essential for anyone troubleshooting print shop RIP (Raster Image Processor) problems.

What Is PostScript?

PostScript was developed by John Warnock and Chuck Geschke at Adobe Systems (1982–1984) as a device-independent page description language. Unlike bitmap formats that specify individual pixels, PostScript describes pages as programs in a stack-based interpreted language. A PostScript file is human-readable ASCII text containing instructions that tell a printer (or software RIP) how to construct the page.

PostScript's key innovations:

• Resolution independence: Curves, text, and fills are described mathematically; the printer renders them at its native resolution (300, 600, 1200, 2400 DPI)
• Bezier curves: Adobe's adoption of Bézier curves in PostScript defined the vector graphics model used in every design tool today
• Fonts as programs: PostScript Type 1 fonts are programs that describe letter shapes, enabling perfect rendering at any size
• Turing completeness: PostScript is a full programming language — it has loops, conditionals, procedures, and data structures

PostScript Levels

PostScript has evolved through three major versions:

Most modern RIPs implement Level 3. Understanding which level a file targets matters when troubleshooting compatibility with older devices.

PostScript File Structure

%!PS-Adobe-3.0          ← PostScript version declaration
%%Title: My Document
%%Creator: Adobe Illustrator 28.0
%%BoundingBox: 0 0 612 792   ← Page dimensions in points (8.5×11 in at 72pt/in)
%%Pages: 1
%%DocumentData: Clean7Bit
%%EndComments

%%BeginSetup
% Resource definitions, font declarations
%%EndSetup

%%Page: 1 1
% Page content
%%EndPage

%%Trailer
%%EOF

The %% comments are DSC (Document Structuring Conventions) — a standard for organizing PostScript files so that tools can process them without fully interpreting the PostScript language.

PostScript Drawing Commands

PostScript uses a stack-based graphics model. Commands push operands and apply them:

%!PS-Adobe-3.0
%%BoundingBox: 0 0 400 400

% Set color (RGB)
1 0 0 setrgbcolor

% Draw a filled rectangle
50 50 300 200 rectfill

% Draw a path (Bézier curve)
0 0 1 setrgbcolor    % Blue
2 setlinewidth
newpath
100 300 moveto
200 400 300 400 400 300 curveto  % Bézier: (x1 y1 x2 y2 x y)
stroke

% Text
/Helvetica findfont 24 scalefont setfont
50 20 moveto
(Hello, PostScript!) show

showpage
%%EOF

Key PostScript operators:

• moveto — Set current point
• lineto, curveto, arc — Path construction
• stroke — Draw path outline
• fill — Fill path interior
• clip — Set clipping region
• gsave / grestore — Push/pop graphics state
• setrgbcolor, setcmykcolor — Color
• setlinewidth, setlinecap, setlinejoin — Stroke attributes
• translate, rotate, scale — Transform current matrix
• showpage — Output page to printer

What Is EPS?

EPS (Encapsulated PostScript) is a restricted subset of PostScript designed for embedding graphics as objects within larger documents. An EPS file:

1. Must contain exactly one page of content
2. Must have a %%BoundingBox comment specifying the exact extent of the artwork
3. Must not execute showpage (or use %%EndPage / %%Trailer outside an EPS context)
4. Can be placed inside other PostScript documents or desktop publishing applications (InDesign, QuarkXPress)

%!PS-Adobe-3.0 EPSF-3.0        ← EPSF (EPS File) declaration
%%BoundingBox: 10 10 500 400   ← llx lly urx ury in points
%%EndComments

% Drawing commands here
% NO showpage — EPS must not trigger page output

The %%BoundingBox defines the clipping rectangle of the illustration. Applications use it to lay out the EPS without rendering it. The HiRes BoundingBox DSC comment provides sub-point precision when needed.

EPS Preview Images

EPS files can embed a low-resolution preview (bitmap thumbnail) for display in applications that cannot render PostScript:

• EPSI (Interchange): ASCII hexadecimal bitmap embedded in DSC comments — works on any platform
• EPSF + PICT (macOS Classic): PICT thumbnail in the resource fork — no longer relevant
• EPSF + TIFF (Windows): TIFF preview in file header (before the PostScript data) — the standard EPS+TIFF format expected by Windows applications

Modern applications (InDesign CC, Illustrator CC) render EPS directly without needing preview images.

Converting EPS and PostScript

# EPS/PS to PDF using Ghostscript
gs -dNOPAUSE -dBATCH -dSAFER \
   -sDEVICE=pdfwrite \
   -dCompatibilityLevel=1.4 \
   -sOutputFile=output.pdf \
   input.eps

# EPS to high-resolution PNG (300 DPI)
gs -dNOPAUSE -dBATCH -dSAFER \
   -sDEVICE=pnggray \
   -r300 \
   -sOutputFile=output.png \
   input.eps

# EPS to PNG with transparency (RGBA)
gs -dNOPAUSE -dBATCH -dSAFER \
   -sDEVICE=pngalpha \
   -r300 \
   -dGraphicsAlphaBits=4 \
   -dTextAlphaBits=4 \
   -sOutputFile=output.png \
   input.eps

# PDF to EPS (distilled PDF → PostScript → EPS)
pdftops -eps input.pdf output.eps

# Convert PS to PDF keeping CMYK colors
gs -dNOPAUSE -dBATCH -dSAFER \
   -sDEVICE=pdfwrite \
   -dProcessColorModel=/DeviceCMYK \
   -dColorConversionStrategy=/LeaveColorUnchanged \
   -sOutputFile=output_cmyk.pdf \
   input.ps

# Batch convert EPS folder to PDF
for f in *.eps; do
    gs -dNOPAUSE -dBATCH -dSAFER -sDEVICE=pdfwrite \
       -sOutputFile="${f%.eps}.pdf" "$f"
done

Python: Processing EPS with Pillow and Ghostscript

from PIL import Image
import subprocess
import os

def eps_to_png(eps_path, output_path, dpi=300, background='white'):
    """Convert EPS to PNG via Ghostscript."""
    cmd = [
        'gs',
        '-dNOPAUSE', '-dBATCH', '-dSAFER',
        '-sDEVICE=pngalpha',
        f'-r{dpi}',
        '-dGraphicsAlphaBits=4',
        '-dTextAlphaBits=4',
        f'-sOutputFile={output_path}',
        eps_path
    ]
    subprocess.run(cmd, check=True, capture_output=True)

    # Flatten alpha onto background
    with Image.open(output_path) as img:
        if img.mode == 'RGBA' and background != 'transparent':
            bg = Image.new('RGB', img.size, background)
            bg.paste(img, mask=img.split()[3])
            bg.save(output_path.replace('.png', '_flat.png'), 'PNG')

# Open EPS directly with Pillow (requires Ghostscript in PATH)
with Image.open('illustration.eps') as img:
    # Pillow calls Ghostscript internally
    img.load(scale=2)  # 2× scale factor
    img.convert('RGB').save('output.jpg', 'JPEG', quality=95)

def extract_eps_boundingbox(eps_path):
    """Read the %%BoundingBox from an EPS file."""
    with open(eps_path, 'rb') as f:
        for line in f:
            line = line.decode('latin-1', errors='ignore').strip()
            if line.startswith('%%BoundingBox:'):
                parts = line.split(':')[1].split()
                return tuple(float(p) for p in parts)  # llx, lly, urx, ury
    return None

bb = extract_eps_boundingbox('logo.eps')
if bb:
    width_pt  = bb[2] - bb[0]
    height_pt = bb[3] - bb[1]
    print(f"Size: {width_pt:.1f} × {height_pt:.1f} points")
    print(f"Size: {width_pt/72:.2f} × {height_pt/72:.2f} inches at 72 pt/in")

EPS vs AI vs SVG vs PDF for Vector Artwork

When EPS Is Still Relevant

Despite PDF's dominance, EPS remains required in specific contexts:

• Legacy print workflows: Older RIPs and prepress systems still expect EPS for spot-color logo placement
• Vinyl cutting / plotter workflows: Many sign-making and CNC plotter software accept EPS but not PDF
• Embroidery digitizing: EPS vector artwork as input to digitizing software
• Signage and large-format printing: Some RIP software for large-format printers still processes EPS natively
• Stock illustration sites: Many stock sites (Getty Images, Shutterstock) accept and distribute vector assets as EPS

Summary

PostScript defined the desktop publishing revolution, and EPS carried its vector graphics model into the age of digital print. While PDF has replaced PostScript as the primary delivery format, understanding PostScript operators, DSC structure, and the EPS BoundingBox mechanism remains essential for anyone working in print production, troubleshooting RIP issues, or processing legacy artwork files. Ghostscript remains the indispensable open-source tool for PostScript/EPS processing in any platform.

Related conversions

Frequent conversions across the catalogue:

• JPG to PNG
• MP4 to MP3
• PDF to DOCX
• PNG to JPG
• MP3 to WAV
• DOCX to PDF