I have been consistently building RAG systems that excel at retrieving text. Better embeddings. Smarter chunking. More sophisticated re ranking. Have squeezed incredible performance gains from text retrieval.
But here's what nobody talks about: most of the
world's knowledge isn't stored in neat paragraphs of text.
It's in diagrams. Screenshots. Charts. Tables.
Code snippets with syntax highlighting. Product photos. Architecture diagrams.
Handwritten notes. Medical images. Technical schematics. Video frames. Audio
transcriptions paired with visual context.
I realized this the hard way last fall. After deploying a RAG system for technical documentation. The
system was excellent at answering conceptual questions. "What's the
difference between async and sync processing?" Perfect answer every time.
Then someone asked "How do I wire up this
component?" and attached a circuit diagram. The system was completely
blind. It couldn't see the image. Couldn't parse the diagram. Couldn't connect
the visual information to the relevant text documentation.
The user had to describe the diagram in words,
ask again, get a text based answer, then manually verify it matched their
visual context. The system that was supposed to save time actually added
friction.
That's when I started building multimodal RAG.
What Multimodal RAG Actually Means
Multimodal RAG extends retrieval augmented
generation to work across different types of content. Not just text, but
images, tables, code, audio, video, and any combination thereof.
The core idea is simple: embed different
content types into a shared vector space where semantic similarity works across
modalities. A user's text query should retrieve relevant images. An uploaded
diagram should retrieve related documentation. A code snippet should pull up
architecture diagrams and explanatory text.
Simple in concept. Complex in execution.
The challenges show up immediately. How do you
embed an image in a way that captures both what it depicts and what it means?
How do you compare the relevance of a text paragraph versus a diagram versus a
data table? How do you present multimodal results to users in a way that makes
sense?
After spending time working through these
problems across different domains. The patterns that emerge are consistent.
Multimodal RAG isn't just better than text only systems. It unlocks entirely
new categories of questions that were previously unanswerable. 🚀
Why Text Only RAG Fails in the Real World
Let's be honest about where traditional RAG
breaks down.
Technical documentation is full of diagrams. A paragraph describing a
system architecture is useful. The actual architecture diagram is essential.
Text only RAG retrieves the paragraph but misses the diagram. Users get
incomplete information.
Product information relies heavily on images. Someone asks
"Do you have this in blue?" and uploads a photo. Text search can't
handle that. You need visual similarity search combined with product metadata.
Financial analysis lives in charts and tables. Quarterly
earnings, market trends, comparative data. These are inherently visual.
Converting them to text loses the structure and visual patterns that make them
meaningful.
Medical diagnosis depends on imaging. X rays, MRIs, pathology
slides. A doctor asking "Have we seen cases similar to this?" needs
visual similarity, not text descriptions of symptoms.
Code repositories mix documentation, code, diagrams, and
screenshots. A developer asking "How do we implement authentication?"
needs to see code examples, architecture diagrams, and configuration
screenshots together, not just text explanations.
The pattern is clear: as soon as your knowledge
base includes non text content (and it definitely does), text only RAG leaves
value on the table. 📉
The Multimodal RAG Architecture
Building multimodal RAG requires rethinking
your entire pipeline. You can't just bolt image search onto your existing text
system. You need an architecture designed for multiple modalities from the
ground up.
Here's what actually works:
Unified embedding space where text, images, and other content types
are embedded into vectors that can be meaningfully compared. Models like CLIP
enable this by training on text image pairs, learning representations where
semantically similar content across modalities ends up close in vector space.
Modality specific processing that handles the unique characteristics of
each content type. Images need visual feature extraction. Tables need structure
preservation. Code needs syntax awareness. Audio needs transcription plus
acoustic features.
Cross modal retrieval that can handle queries in any modality
returning results in any modality. Text query retrieves images. Image query
retrieves text. Table query retrieves related charts.
Intelligent ranking that compares relevance across different
content types. Is this diagram more relevant than that paragraph? The answer
depends on the query and context.
Multimodal synthesis where the LLM can reason about different
content types together, generating answers that reference text, describe
images, interpret tables, and explain code in a unified response. 🎯
Image Retrieval: The First Step
Most organizations starting with multimodal RAG
begin with images because they're everywhere and the technology is mature.
Vision language models like CLIP create
embeddings for both images and text in the same vector space. This enables text
to image search. A user types "authentication flow diagram" and your
system retrieves relevant flowcharts, even if the image filenames are unhelpful
and there's no surrounding text description.
But naive image search has problems. Basic
embeddings capture high level semantics but miss fine details. Two circuit
diagrams might embed similarly even though they show completely different
circuits. You need additional techniques for precision.
OCR extraction pulls text from images. Diagrams often contain
labels, annotations, and embedded text that carry crucial information. Extract
this text, embed it separately, and use it alongside visual embeddings. A
network diagram with labeled components becomes searchable by those component
names.
Layout analysis understands document structure. A page from a
manual might contain text, diagrams, and tables. Knowing the spatial
relationships between elements improves retrieval. The diagram explaining step
3 should be strongly associated with the text describing step 3.
Metadata enrichment adds context. When was the image created? Who
created it? What document does it belong to? Which section? This metadata helps
with filtering and ranking. A recent diagram from the official documentation
should rank higher than an old screenshot from a user forum. 📸
Tables: Structure Matters
Tables are everywhere in business documents.
Financial data, product specifications, comparison charts, experimental
results. But tables are notoriously hard for RAG systems to handle well.
Text only systems typically convert tables to
markdown or CSV format, then chunk them like any other text. This loses crucial
information. The spatial layout of a table conveys meaning. Column headers, row
labels, cell relationships, visual groupings. Flattening a table to text
destroys this structure.
Multimodal RAG treats tables as first class
objects. You preserve the tabular structure during indexing. Headers stay
linked to their columns. Rows maintain their relationships. The system
understands that a cell's meaning depends on its row and column context.
When embedding tables, you want representations
that capture both content and structure. Recent approaches use table specific
transformers that understand row column relationships and can answer questions
about the table as a structured object, not just a blob of text.
The real power comes from combining table
understanding with retrieval. A user asks "Which product had the highest
growth?" The system retrieves the relevant table, understands its
structure, and can directly answer from the tabular data instead of hoping a
text summary mentions the answer.
I've seen this transform financial analysis
workflows. Analysts used to manually search through reports, find tables,
extract data, and analyze it. Now they ask questions and the system finds
relevant tables, interprets them correctly, and provides answers grounded in
the actual data. Time from question to insight dropped from hours to seconds. 📈
Code as a Modality
Code repositories are multimodal by nature.
Implementation files, documentation, architecture diagrams, configuration
examples, test cases, deployment scripts. Treating code as just another text
document misses its unique properties.
Code has syntax, structure, and semantics that
matter for retrieval. A function definition is different from a function call.
A class declaration is different from an instantiation. Import statements
reveal dependencies. Comments explain intent.
Code aware embeddings understand these
distinctions. They recognize that two functions with similar names but
different implementations are not equivalent. They capture the semantic meaning
of what code does, not just what it looks like textually.
But code retrieval goes beyond embeddings. You
want to search by functionality ("show me authentication examples"),
by API usage ("how do I use the User model?"), by pattern
("decorator implementations"), or by visual structure ("class
hierarchies").
The most effective approach combines code
embeddings, abstract syntax tree analysis, documentation extraction, and cross
references to related diagrams and docs. When someone asks about
authentication, they should get code examples, architecture diagrams showing
where auth fits, configuration snippets, and API documentation together.
I deployed this for a fintech company's
internal developer platform. Before multimodal code retrieval, developers spent
significant time hunting through repos for examples. They'd find code but not
understand the architecture. Or find diagrams but not see implementation. The
multimodal system connected everything. Code examples came with architectural
context and configuration. Onboarding time for new developers dropped by 40%. 🔧
Video and Audio: The Temporal Dimension
Video and audio add temporal complexity. A one
hour technical presentation contains dozens of topics, visual aids, code
examples, and explanations. How do you make this searchable?
The answer is temporal segmentation combined
with multimodal indexing. You break videos into segments at natural boundaries
like scene changes or topic shifts. For each segment, you extract a
representative frame, transcribe the audio, pull out any on screen text, and
create embeddings that capture both visual and audio content.
Now when someone asks "Where does the
presenter explain database sharding?" the system can retrieve the specific
2 minute segment, show a representative frame, and provide the transcript
excerpt. Users jump directly to relevant moments instead of watching entire
videos hoping to find what they need.
This transformed training material
accessibility at a healthcare organization I worked with. They had hundreds of
hours of recorded training sessions, procedure demonstrations, and expert
talks. Before multimodal retrieval, this content was essentially lost. People
knew it existed but couldn't find specific information. After implementing
video segmentation and multimodal indexing, utilization of training videos
increased 10x. Medical staff could search "catheter insertion
technique" and jump to the exact moment in the exact video where it's
demonstrated. 🎥
The Cross Modal Retrieval Challenge
The hardest part of multimodal RAG is ranking
results across different modalities. When a user asks a question, you might
have highly relevant text passages, somewhat relevant diagrams, and
tangentially related code snippets. How do you decide what to show?
Pure embedding similarity doesn't work.
Different modalities embed differently even when semantically equivalent. A
diagram explaining concept X might have lower cosine similarity to the query
than a text passage mentioning X in passing. But the diagram is more useful.
Effective cross modal ranking uses learned
relevance models trained on user behavior. When users consistently click on
images over text for certain query types, the system learns to rank images
higher for similar queries. When tables get more engagement for data questions,
they rise in rankings.
The system also considers query intent. A
question starting with "Show me" or "What does it look
like" signals preference for visual content. "How much" or
"Compare" suggests tables might be most relevant. "How do I
implement" indicates code examples are valuable.
Context matters too. The same query in a
technical documentation system versus a product catalog should return different
modality mixes. Documentation users often want diagrams and code. Product
catalog users want images and specifications.
This adaptive ranking is where multimodal RAG
becomes truly intelligent. Not just retrieving diverse content, but
understanding what format will be most useful for each specific query and user
context. 📊
Presentation: Making Multimodal Results Useful
Retrieving multimodal content is only half the
battle. Presenting it in a way users can actually use is equally important.
Text only RAG has it easy. Return a few
paragraphs, let the LLM synthesize, done. Multimodal results require thoughtful
interface design.
Visual prominence for non text content. Images, diagrams, and
charts should be displayed prominently, not buried in text. Users' eyes are
drawn to visuals. Make them easy to see. I've tested layouts where images were
small thumbnails versus large featured displays. Engagement with visual content
was 3x higher with prominent display.
Contextual integration where each piece of content is presented with
just enough context to understand its relevance. An image without explanation
is confusing. A paragraph explaining why this diagram matters helps users
quickly assess relevance. Too much explanation defeats the purpose of visual
content. Balance is key.
Progressive disclosure that shows the most relevant content first but
lets users dig deeper. Initial view shows top 3 results across modalities. One
image, one text excerpt, one table or code sample. Click to see more of each
type. Users who found what they need stop there. Users who need more keep
exploring without being overwhelmed initially.
Modality specific interactions. Images should be zoomable and downloadable.
Tables should be sortable and filterable. Code should be copyable with syntax
highlighting maintained. Video should jump to relevant timestamps and allow
playback speed control.
The goal is seamless integration where users
don't think about modalities. They just get the most useful information in the
most useful format. 🎨
Implementation Challenges
Building multimodal RAG is harder than text
only systems. Several challenges consistently appear.
Computational cost increases significantly. Processing images,
video, and audio requires more compute than text. Vision language model
embeddings are expensive at scale. Video processing is compute intensive.
Budget for 3 to 5x the infrastructure costs of text only RAG. One organization
I worked with underestimated this and had to redesign their pipeline for
efficiency after hitting budget constraints.
Storage requirements explode. Images and videos are large. Storing
raw content plus embeddings plus extracted features adds up quickly. A 10GB
text corpus might expand to 100GB when you include associated images and
videos. Factor this into your infrastructure planning. Consider compression
strategies and tiered storage where older content moves to cheaper storage.
Latency concerns multiply. Embedding an image takes longer than
embedding text. Retrieving and transmitting images to users is slower than
text. Multimodal systems need aggressive caching and optimization to stay
responsive. Users expect sub second responses for simple queries. Achieving
this with multimodal content requires careful engineering.
Quality control gets complicated. With text, you can usually
tell if retrieval failed. With multimodal content, evaluation is harder. Is
this image relevant? Somewhat relevant? It depends on what the user actually
wanted, which may not be clear from the query. You need robust evaluation
frameworks and extensive user testing.
Format inconsistencies create headaches. Images come in different
sizes, resolutions, formats. Tables might be in PDFs, spreadsheets, or HTML.
Code might be in files, screenshots, or documentation. Normalizing all this
requires robust preprocessing pipelines that handle edge cases gracefully. 🔧
Evaluation: Measuring Multimodal Performance
How do you know if your multimodal RAG system
is actually working well? Traditional metrics like precision and recall are
necessary but insufficient.
Modality coverage measures whether you're actually retrieving
diverse content types. If 95% of results are text despite having rich image
libraries, something's wrong with your ranking. Track the distribution of
modalities in top results. A healthy multimodal system shows balanced
representation.
Cross modal relevance evaluates whether retrieved content in
different modalities actually relates to the query. An image might be visually
similar but conceptually irrelevant. A table might contain related data but not
answer the specific question. Manual evaluation on a sample of queries reveals
these issues.
User engagement tracks what people actually use. Do they view
the images you retrieve? Do they click on code examples? Do they skip over
tables? Behavior reveals relevance better than any automatic metric. High skip
rates for a particular modality indicate ranking problems.
Task completion is the ultimate measure. Can users accomplish
their goals? For technical documentation, can engineers find the diagrams they
need? For product search, do customers find what they're looking for? For
medical knowledge bases, do doctors get useful case comparisons? Track these
outcome metrics relentlessly.
Time to answer measures efficiency gains. Multimodal RAG
should reduce the time from question to satisfactory answer. If users are
spending more time than with previous systems, something's wrong despite good
retrieval metrics.
Build evaluation into your system from day one.
Log everything. Track which results users engage with, which they skip, which
queries fail. A/B test ranking approaches. Collect explicit feedback through
ratings. The systems that improve fastest are those with the richest evaluation
data. 📈
The Synthesis Challenge
Retrieving multimodal content is one thing.
Having the LLM reason about it is another.
Modern large language models are increasingly
multimodal themselves. GPT 4 Vision, Claude with image understanding, Gemini
with native multimodality. They can look at images, read tables, analyze
charts, and discuss code with visual context.
This enables genuine multimodal synthesis. The
LLM can say "As shown in the second diagram, the authentication flow
involves three steps..." or "According to the table in the Q2 report,
revenue increased by 33%..." or "The code example demonstrates this
pattern with a decorator approach..."
The system isn't just showing you diverse
content types. It's reasoning across them, connecting insights from text with
evidence from images, supporting claims with data from tables, and illustrating
concepts with code examples.
This is where multimodal RAG becomes truly
powerful. Not just retrieving diverse content, but synthesizing it into
coherent answers that leverage the strengths of each modality. Text provides
detailed explanation. Images offer immediate visual understanding. Tables
present structured data. Code shows concrete implementation.
I've watched users' reactions to well
synthesized multimodal answers. There's a moment of "Oh, now I actually
understand" that doesn't happen with text only responses. The combination
of modalities creates comprehension that no single format achieves alone. 🎯
The Future Is Already Here
Multimodal RAG isn't experimental technology.
It's production ready and delivering value today. But we're still early in
understanding what's possible.
3D content retrieval for CAD models, architectural designs, product
designs. Imagine asking "Show me similar bracket designs" and getting
3D models you can rotate and inspect. The embedding technology exists. The
challenge is building intuitive interfaces for 3D content exploration.
Interactive diagrams that aren't just images but structured objects
the AI can manipulate and explain. "Show me this flowchart but simplified
for a non technical audience." The system doesn't just retrieve a simpler
diagram. It generates one, preserving the essential logic while removing
complexity.
Real time multimodal streams where the system processes live video,
extracts information on the fly, and answers questions about what's happening
now. Security monitoring becomes "Has anyone wearing a red jacket entered
through the north entrance today?" Manufacturing quality control becomes
"Show me all products from batch 47 that had visual defects."
Collaborative multimodal workspaces where teams share images, diagrams, code, and
documents, and the AI helps connect everything together. "Find all the
architecture diagrams related to this code module" across your entire
organization's content. The system understands relationships between artifacts
and surfaces relevant connections.
Generative multimodal augmentation where the system doesn't just retrieve
existing images but generates new visualizations to explain concepts.
"Show me a diagram of how this algorithm works" when no such diagram
exists. The system creates one based on understanding the text description.
Starting Your Multimodal Journey
If you're convinced multimodal RAG is necessary
(and it is), how do you actually get started?
Begin with images because the technology is mature and the value
is immediate. Most organizations have images scattered throughout their
documentation, presentations, and knowledge bases. Making these searchable
delivers quick wins. Start with vision language models like CLIP for embedding.
Implement text to image and image to text search. Measure the impact on user
satisfaction.
Add tables next if your domain involves data. Financial
services, e commerce, analytics, research. Structured data is everywhere and
current systems handle it poorly. Implement table aware processing that
preserves structure. Enable queries that can be answered directly from tabular
data.
Incorporate code when documentation includes implementation
examples. Developer documentation, technical tutorials, integration guides.
Code aware retrieval helps users find relevant examples and understand
implementation patterns.
Tackle video last because it's the most complex. Start with high
value video content that users frequently reference. Training materials,
recorded presentations, product demonstrations. The processing is expensive but
the payoff for searchable video content is enormous.
Build incrementally rather than trying to do everything at once.
Each modality you add delivers value independently. You don't need all
modalities working perfectly before launching. Ship image search, measure
impact, iterate. Add tables, measure impact, iterate. This approach reduces
risk and accelerates learning.
Invest in evaluation from the start. Multimodal systems are
complex. You need data to understand what's working and what isn't. Log user
interactions. Track engagement by modality. Collect explicit feedback. Use this
data to tune your ranking algorithms and improve retrieval quality. 🚀
The Economic Argument
Multimodal RAG costs more to build and operate
than text only systems. But the ROI is compelling when you consider the full
picture.
Reduced search time directly impacts productivity. If knowledge
workers spend 20% of their time searching for information, and multimodal RAG
cuts that by half, you've unlocked 10% productivity improvement. For a 100
person engineering team, that's 10 full time equivalents worth of capacity.
Better decisions from having complete information. Text only
systems force users to make decisions with incomplete context because they
can't find relevant visual information. Multimodal systems surface diagrams,
charts, and images that inform better choices. The value of better decisions is
hard to quantify but often exceeds the cost of the system.
Reduced support burden when users can self serve effectively. If your
documentation chatbot can actually show users the diagram they need instead of
describing it inadequately, support ticket volume drops. Customer satisfaction
increases. Support costs decrease.
Competitive advantage in customer facing applications. Product
search that works with images. Technical support that understands screenshots.
Medical diagnosis that leverages imaging. These capabilities differentiate you
from competitors still limited to text.
The question isn't whether you can afford to
build multimodal RAG. It's whether you can afford not to.
The Bottom Line
Text only RAG was a good start. Multimodal RAG
is what production systems actually need to serve real users solving real
problems.
The upgrade is substantial. More complex
architecture, higher costs, longer development cycles, new technical
challenges. But the capability gap between text only and multimodal systems is
enormous. Questions that were impossible to answer become straightforward. User
satisfaction jumps because the system actually understands their visual
context.
The organizations building multimodal RAG now
will have significant advantages. They'll attract users because their systems
actually work across all content types. They'll retain users because the
experience is dramatically better. They'll extract more value from their
existing content because it's finally searchable and usable.
The rest will keep telling users "I can't
see images" while their competitors deliver visual intelligence. They'll
watch their carefully curated image libraries go unused because they're not
indexed. They'll lose users who expect AI systems to understand the full
richness of human communication, not just text.
Start with image retrieval if you're new to
multimodal. It delivers immediate value and the technology is mature. Add
tables when you need structured data understanding. Incorporate code when
documentation includes implementation examples. Build incrementally toward full
multimodal capability.
The future of RAG isn't just about better text
retrieval. It's about systems that understand information the way humans do
across all modalities, with visual and textual reasoning integrated seamlessly.
That's what multimodal RAG enables. And it's
available today, not in some distant future. 🚀
#multimodalAI #RAG #computervision
#machinelearning #artificialintelligence #dougortiz