Technology // Overview

How a machine vision inspection system is built

The parts of an inspection and reject system, what each one does, and how it is chosen for your product and line.

Technical review: Frank GuoReviewed 24 September 2026

// Short answer

A machine vision inspection system is more than a camera. It combines a trigger, an industrial camera and lens, lighting designed around the defect, inspection software that turns the image into a pass or fail decision, a link to the line PLC, and a reject mechanism that removes failed products, ideally with a sensor that confirms each removal. Reliability depends on getting every link right on your own product and line.

// Architecture

The inspection chain, end to end

Every station we build follows this chain. The numbers in the drawing match the component table below.

[Schematic]Block diagram · not to scale

Swipe sideways to see the whole drawing →

[1–3]: Capture: trigger, camera and lens, lighting

[4]: Decision: inspection software

[5]: Line PLC: tracking and SKU selection

[6–7]: Reject and confirmation

[8]: Records: reject images and counts

// Components

What each part does and what decides the choice

None of these is chosen from a catalogue alone. Each is confirmed on your samples and your line.

Components of a machine vision inspection system
Component	Role	What decides the choice	Typical question
[1] Trigger	Tells the station a product is in position.	Product spacing, speed changes, product shape and transparency.	Photo-sensor, or encoder for variable speed?
[2] Camera	Captures the image to be inspected.	Smallest defect vs field of view (resolution), speed, colour or monochrome, area-scan for discrete parts or line-scan for continuous material.	How many cameras to see every face that matters?
[2] Lens	Projects the scene onto the sensor.	Field of view, working distance, distortion; telecentric lenses where measurement must ignore small height changes.	Standard lens or telecentric?
[3] Lighting	Makes the defect visible and the image repeatable.	Surface (glossy, matte, clear), defect type; geometry such as front, low-angle, back, dome or coaxial light; strobing for fast lines.	Which angle separates the defect from the background?
[4] Inspection software	Turns the image into a decision and data.	Rule-based tools for defined faults; deep-learning tools for variable appearance defects; code reading and OCR.	Smart camera, PC or vision controller?
[5] PLC link	Delivers pass/fail and receives the running SKU.	Your PLC make and model and the protocols the chosen camera or controller supports.	Digital I/O or industrial network?
[6] Reject	Removes failed products from the line.	Product weight and stability, spacing, available air, space on the conveyor.	Air jet, pusher or diverter?
[7] Confirmation	Proves the failed product actually left.	Criticality of the defect and audit requirements.	What happens if a reject is not confirmed?
[8] Records	Keeps reject images, counts and results.	Traceability needs, storage, whether results go to MES or a dashboard.	How long are images kept, and who reviews them?

// Processing

Smart camera, PC or vision controller

Where the inspection software runs changes cost, capacity and maintenance. The software itself can stay the same.

Comparison of vision processing architectures
Architecture	What it is	Suits	Watch out for
Smart camera	Camera, lighting control and inspection software in one housing (HIKROBOT SC5000X / SC6000 run SC_VisionMaster).	One or two checks from a single view; compact stations.	Processing headroom for many tools or deep learning on one part.
PC with industrial cameras	Separate GigE Vision or USB3 Vision cameras connected to an industrial PC running VisionMaster.	Several cameras, heavier processing, operator screen and image storage.	PC hardening for the plant environment and its lifecycle.
Vision controller	A purpose-built industrial computer for multi-camera stations with camera ports and digital I/O.	Multi-camera stations that need a robust, cabinet-mounted unit.	Port and I/O count for later extensions.

HIKROBOT states that the same VisionMaster tool-chain runs on its smart cameras and on PC and vision-controller stations, and that VisionMaster is compatible with the GigE Vision and USB3 Vision standards (HIKROBOT download centre and Machine Vision Smart Product Catalog 2025 Q4, both checked 24 September 2026). GigE Vision and USB3 Vision cameras expose a common programming interface through the GenICam standard hosted by EMVA.

// Decision tools

Rule-based tools and deep learning

Most stations use both. The choice is made per check, not per project.

Rule-based

Defined, measurable faults

Position, presence, dimensions, code reading and print verification against a reference. Predictable, explainable and quick to validate.

Works best whenThe defect can be described as a measurable rule

Deep learning

Variable appearance defects

Scratches, marks and contamination that vary in shape, or natural products whose appearance varies. Learns from labelled images of good and bad parts.

Works best whenEnough representative images of each defect exist

How to choose between rule-based and deep learning →

// PLC communication

Protocols depend on the model, not the brand

We never assume a protocol. We check the exact camera, reader or controller model against your PLC before quoting.

PLC communication options by product type
Product type	Protocols listed by the vendor	Source
VisionMaster software (PC)	TCP/IP, Modbus, serial port, UDP, EtherNet/IP and other common industrial protocols	HIKROBOT Smart Product Catalog 2025 Q4
Smart code reader (example: IDH7000 row)	SmartSDK, TCP, FTP, PROFINET, EtherNet/IP, Modbus, UDP, serial	HIKROBOT Smart Product Catalog 2025 Q4
Any station	Hard-wired digital I/O for trigger, pass/fail and reject	Standard practice

Protocol support differs between smart cameras, code readers and PC software, and between models. For the full integration method, see PLC & reject integration.

// FAQ

Technology questions

What components make a reliable vision inspection and reject system?

A trigger that tells the station when a product arrives, a camera and lens matched to the smallest defect and the field of view, lighting chosen so the defect stands out, inspection software that turns the image into a decision, a link to the line PLC, a reject mechanism that removes failed products, and ideally a sensor that confirms each removal. A weakness in any one link, for example a reject that sometimes misses, undoes the rest.

Should we use a smart camera or a PC-based system?

A smart camera suits one or two checks from one view and keeps the station compact. A PC or vision controller with separate industrial cameras suits several cameras, heavier processing such as deep learning, or stations that need an operator screen and image storage. HIKROBOT runs the same VisionMaster tool-chain on its SC5000X and SC6000 smart cameras (SC_VisionMaster) and on PC and vision-controller stations, which keeps recipes consistent across both.

When are telecentric lenses needed?

Mainly for measurement. A normal lens changes the apparent size of a part when its distance to the camera changes; a telecentric lens keeps the magnification constant within its working range, so dimensions read correctly even if the part height varies slightly. Presence, label and code checks rarely need one. Whether your measurement does is decided during the sample test.

Do we need an encoder on the conveyor?

If line speed varies or the conveyor stops and starts, yes: the encoder lets the PLC track a failed product to the reject point by distance rather than time, so the reject still hits the right product. On lines that run at a constant speed, a time delay is often enough.

Can we use cameras from other brands?

VisionMaster is stated to be compatible with the GigE Vision and USB3 Vision standards, so cameras from other makers that follow those standards can be acquired (HIKROBOT Machine Vision Smart Product Catalog, 2025 Q4). Device control is most complete with HIKROBOT hardware. We confirm the exact combination for your station before quoting.

Sources

HIKROBOT Machine Vision Smart Product Catalog 2025 Q4 (PDF) (vendor document, checked 24 Sep 2026)
HIKROBOT VisionMaster product page (vendor page, checked 24 Sep 2026)
HIKROBOT download centre (VisionMaster, SC_VisionMaster) (vendor page, checked 24 Sep 2026)
EMVA — GenICam standard (standards body, checked 24 Sep 2026)

HIKROBOT VisionMaster integration →How we deliver a project →PLC & reject integration →All applications →Cost & budget guide →

// Line integration

Talk through your line with an engineer

Tell us the product, the check and your PLC. We will tell you which architecture fits and what has to be confirmed on site.

Request a Vision Assessment