analyze-pptx

name	analyze-pptx
description	Use when analyzing a .pptx file's format, colors, fonts, layout, or design preferences. Trigger on requests like "analyze this PPT", "what colors does this slide use", "extract the style from this presentation".

Analyze PPTX Format & Style

Overview

Extract format, colors, fonts, sizes, shapes, and layout from .pptx files by unzipping and parsing the internal XML structure. No external dependencies needed.

When to Use

• User wants to understand a PPT's visual style/design preferences
• Need to replicate a PPT's color scheme or format in another context (e.g., HTML slides, LaTeX)
• Comparing design styles across presentations
• Extracting a "style profile" before creating new slides matching an existing deck

Core Technique

.pptx is a ZIP archive containing XML files. Unzip and parse the XML to extract all styling data.

Step 1: Unzip

mkdir -p /tmp/pptx_extracted
unzip -o "file.pptx" -d /tmp/pptx_extracted

Step 2: Identify Structure

Key files:

ppt/slides/slide{N}.xml          # Slide content, shapes, inline styles
ppt/slides/_rels/slide{N}.xml.rels  # Image/layout references per slide
ppt/slideLayouts/slideLayout{N}.xml # Layout templates
ppt/slideMasters/slideMaster{N}.xml # Master slide definitions
ppt/theme/theme{N}.xml           # Theme color palette & font scheme
ppt/media/                       # Embedded images
ppt/presentation.xml             # Slide dimensions, slide order

To find which theme a slide uses, follow the chain:

slide → _rels → slideLayout → _rels → slideMaster → _rels → theme

Step 3: Extract Colors

The XML is often single-line. Use sed to split before grepping:

# Explicit RGB colors (most important - these are custom overrides)
cat ppt/slides/slide1.xml | sed 's/>/>\n/g' | \
  grep -o 'srgbClr val="[0-9A-Fa-f]*"' | sort | uniq -c | sort -rn

# Theme color references (mapped to theme palette)
cat ppt/slides/slide1.xml | sed 's/>/>\n/g' | \
  grep -o 'schemeClr val="[a-zA-Z0-9]*"' | sort | uniq -c | sort -rn

Step 4: Extract Theme Color Palette

# Get full color scheme from theme file
cat ppt/theme/theme{N}.xml | sed 's/>/>\n/g' | \
  sed -n '/a:clrScheme/,/\/a:clrScheme/p'

Theme color mapping:

XML Name	Role
dk1	Dark text 1 (usually black)
lt1	Light background 1 (usually white)
dk2	Dark text 2
lt2	Light background 2
accent1-accent6	Accent colors
hlink	Hyperlink color
folHlink	Followed hyperlink

Step 5: Extract Fonts

# Latin (Western) fonts
cat ppt/slides/slide1.xml | sed 's/>/>\n/g' | \
  grep -o 'latin typeface="[^"]*"' | sort | uniq -c | sort -rn

# East Asian fonts (Chinese/Japanese/Korean)
cat ppt/slides/slide1.xml | sed 's/>/>\n/g' | \
  grep -o 'ea typeface="[^"]*"' | sort | uniq -c | sort -rn

Font reference values:

• +mj-lt / +mj-ea = Major (heading) font from theme
• +mn-lt / +mn-ea = Minor (body) font from theme
• Explicit name (e.g., 微软雅黑) = Custom override

Step 6: Extract Font Sizes

cat ppt/slides/slide1.xml | sed 's/>/>\n/g' | \
  grep -o 'sz="[0-9]*"' | sort | uniq -c | sort -rn

Size values are in hundredths of a point: 1200 = 12pt, 3200 = 32pt.

Step 7: Extract Shapes & Layout

# Shape types
cat ppt/slides/slide1.xml | sed 's/>/>\n/g' | \
  grep -E 'prstGeom|custGeom' | grep -o 'prst="[^"]*"' | sort | uniq -c | sort -rn

# Count total shapes
cat ppt/slides/slide1.xml | sed 's/>/>\n/g' | grep -c '<p:sp'

# Count images
cat ppt/slides/slide1.xml | sed 's/>/>\n/g' | grep -c 'blipFill'

# Line widths (in EMUs: 12700 = 1pt)
cat ppt/slides/slide1.xml | sed 's/>/>\n/g' | \
  grep -o 'ln w="[0-9]*"' | sort | uniq -c | sort -rn

Step 8: Extract Text Content

cat ppt/slides/slide1.xml | sed 's/</\n</g' | \
  grep 'a:t>' | sed 's/.*<a:t>//; s/<\/a:t.*//'

Output Format

Present analysis as a structured report:

1. Color Palette - Table with HEX, swatch description, usage frequency, inferred role
2. Theme Colors - Mapped accent/text/background colors
3. Fonts - Primary fonts for Latin and CJK, with frequency
4. Font Sizes - Distribution indicating content density style
5. Layout - Shape count, types, images, structural pattern
6. Style Summary - Table summarizing overall design personality (dense vs. sparse, formal vs. casual, color mood)

Common Pitfalls

• macOS grep lacks -P flag — use sed 's/>/>\n/g' to split XML then pipe to basic grep -o
• Single-line XML — always split before grepping; raw XML is typically one giant line
• Theme indirection — slide colors referencing schemeClr need theme file lookup to get actual HEX
• Multiple themes — large decks may have many theme files; follow the rels chain per slide
• EMU units — positions/sizes in XML are in EMUs (914400 EMU = 1 inch)