MV-CS050-10GM(NPOE)View part & specifications →Browse camera options →ホーム / Case studies / Light-on-dark characters on paper
Application study · Print and label inspectionPaper character imaging: separate bright strokes from a dark field
The source paper example shows three lines of bright numeric characters on a dark rectangular field. A red bar creates a practical starting point for checking character contrast and spacing on this print/substrate combination.
Match the reader to the actual print polarity before judging recognition performance.
- Light in sourceLS-2BS14738-RGBW · red
- EvidenceReal application-lab image
- Imaging kitCamera, lens and fixture proposed
- AcceptanceValidate on representative parts
Test stationIncluded light holdersカメラレンズ照明Part視野
Drag to rotate · scroll to zoomWalk through this setup 5 guided stops
From component to inspection
Understand each choice.
Choose a stop to frame the part in 3D and see why it belongs in this setup. The component notes and links remain available if 3D cannot load.
Proposed component
MV-CS050-10GM(NPOE)
5 MP monochrome global-shutter camera proposed for a contrast trial. Confirm field, sampling, exposure and algorithm on the actual application.
Proposed component
LS-KF1628M-ML
Proposed 16 mm C-mount macro lens at its printed 0.1x magnification / 152 mm working-distance pair. The proposed 2448 × 2048 sensor with 3.45 µm pixels gives a derived 84.456 × 70.656 mm field; confirm focus, coverage and residual distortion on the real sample.
Tested component
LS-2BS14738-RGBW
Red 147 × 38 × 27 mm bar explicitly identified in the paper-character example. The RGBW catalog suffix lists individual colour options; this kit selects red.
Proposed component
LS-BT-XZ-G-6-6045
600 mm column, 600 × 450 mm breadboard, XZ adjustment, glass tray and two lighting holders as listed. Proposed bench fixture; confirm loads, travel and camera/lens clamps.
Inspect the real capture
Follow the contrast to the part.
Match the reader to the actual print polarity before judging recognition performance.
Camera and available lens CAD are published models. Lens and light envelopes use printed dimensions. The linked station uses its published base size and column height; carriage, brackets, fittings, parts and spacing are illustrative. Confirm load, travel, fasteners and clearances before ordering. Light paths explain the arrangement and do not simulate optical performance. Representative part geometry is illustrative, not reconstructed inspection evidence. The specimen and lighting angle are representative, not dimensions or settings recovered from the source capture.
From the demo to your test benchカメラMV-CS050-10GM(NPOE)View part & specifications →Browse camera options → Imaging lens
LS-KF1628M-MLView part & specifications →Browse imaging lens options → Inspection light
LS-2BS14738-RGBWView part & specifications →Browse inspection light options → Test station & mounts
LS-BT-XZ-G-6-6045View part & specifications →Browse test station & mounts options →
Build around the parts you can buy.
Explore each component, check its specifications and compare alternatives. The proposed quote includes the linked test station; its catalog listing includes two lighting holders.
MV-CS050-10GM(NPOE)View part & specifications →Browse camera options →LS-KF1628M-MLView part & specifications →Browse imaging lens options →LS-2BS14738-RGBWView part & specifications →Browse inspection light options →LS-BT-XZ-G-6-6045View part & specifications →Browse test station & mounts options →Mount the optics with intent
The station is an optical test bench, with its two lighting holders included in the catalog listing. The 3D column and base follow the published height and footprint. Carriages, clamps and part supports are schematic: confirm camera screw pattern, lens support, light fasteners, permissible load and actual travel before ordering.
Configure the mounting station →Complete the electrical system
Select a controller against the exact light voltage, drive mode and power, then confirm camera data/power/I/O cables and a suitable PC. These are not silently added to the proposed optical kit.
Lighting application-lab catalog capture
Evidence you can inspect
Visible in the images
Three numeric lines and their spaces are visible as light strokes against a dark field.
What the source reports
The catalog identifies paper character inspection and the red 147 mm bar.
How to use this evidence
No decoded text, recognition confidence, print-size measurement, speed or repeatability result is given.
What the camera saw
Cropped from the source test sheet; original test annotations are retained. Captures are not generated or enhanced. Drag the comparison slider or use the image buttons.
The challenge
Background shade, ink density and print texture can change stroke contrast without changing the intended text.
A positive light-on-dark image needs different segmentation behaviour from a dark-on-light print.
How it was solved
The source captions this as paper character inspection with a red bar. It does not identify the ink chemistry or explain why the characters appear bright.
Test the real print and substrate with the proposed monochrome camera. Keep character polarity and spacing in the reader setup rather than assuming the source recipe transfers to other materials.
Why it works
- 1
A selected wavelength can change the reflected contrast between a print and its background; the supplied image records the observed result.
- 2
Readable-looking strokes are evidence of contrast, not a measured OCR result or a verified text match.
From image contrast to a production decision
What to validate on your part
A useful sample image is the starting point. These are the checks that turn the concept into a defensible inspection.
- 01
Keep the true strings
Build a labelled set covering all required characters, separators and line layouts.
- 02
Vary print and substrate
Include accepted density changes, weak strokes, background texture and damaged print.
- 03
Measure substitutions separately
Record wrong characters as well as no-reads under the final focus and exposure.
Explore your inspection requirementsNo limit from motion
How many pixels cover your feature?
Compare feature coverage, camera pixel requirements and exposure using your own planning inputs. These are calculated planning values, not inspection results or an accuracy specification.
Editable planning scenario. Adjust these example inputs for your application; they are separate from the source test and 3D setup. Motion allowance and target coverage are starting points to validate, not acceptance limits. Pixel count starts from the proposed camera's catalog resolution.
Enter finite numbers in every field. Field width, feature width, target coverage, exposure and allowed motion must be greater than zero; horizontal pixel count must be a positive whole number; material speed may be zero. Use values within the supported numeric range if a calculation cannot be represented.
Object sampling mm/px
Pixels across feature px
Horizontal pixels for target px
Motion during exposure px
Exposure ceiling from motion µs
Formulas and assumptions
The field, feature, speed and exposure start with neutral example values. They are not taken from the source test or the 3D illustration. Allowed motion starts at an editable 0.5-pixel example; it is not a recommended acceptance limit. Target coverage starts at an editable 5-pixel example; it is not a recommended detection or measurement threshold. The horizontal pixel count starts from the catalog Resolution row for MV-CS050-10GM(NPOE). Use the effective width after cropping, binning or decimation if those modes are enabled.
- Object sampling (mm/px) = field width (mm) / horizontal pixels.
- Pixels across feature = feature width (mm) / object sampling (mm/px).
- Horizontal pixels for target = field width (mm) × target pixels across feature / feature width (mm), rounded up to a whole pixel.
- Motion (px) = speed (mm/s) × exposure (µs) / 1,000,000 / object sampling (mm/px).
- Exposure for allowed motion (µs) = allowed motion (px) × object sampling (mm/px) / speed (mm/s) × 1,000,000.
The exposure result is the maximum duration from this motion allowance alone. At zero speed, motion sets no exposure limit; the camera, lighting, saturation and other constraints still apply. A shorter exposure does not itself guarantee a reliable inspection.
Field width and feature width refer to the same object plane. The motion calculation assumes uniform linear motion parallel to the field-width direction and a single exposure. It does not model perspective, vibration, rolling-shutter distortion, diffraction, defocus or optical distortion. A strobe may change the effective exposure.
The target result is a horizontal sampling requirement, not a camera recommendation or a change to the selected camera. It uses the effective image width after cropping, binning or decimation and does not determine the vertical resolution or sensor size. Pixel coverage alone does not establish detectability or measurement accuracy. Validate contrast, lens performance, working distance, illumination, calibration, camera exposure limits and the inspection algorithm on representative parts. Changing field width does not change the 3D model or certify that the proposed lens can achieve that field.
The set-up and the parts
| Tested light | LS-2BS14738-RGBW, red |
|---|---|
| Source camera / lens | Not specified in the source image caption; proposed parts below |
| Proposed lens point | 0.1x at 152 mm, printed lens pair |
| Derived proposed field | 84.456 × 70.656 mm = sensor dimensions / 0.1x; not a source test field |
| Bar housing (printed) | 147 × 38 × 27 mm |
| Mounting (proposed) | LS-BT-XZ-G-6-6045; 600 mm column, 600 × 450 mm base, glass tray and two included lighting holders |
照明TestedLS-2BS14738-RGBW
Red 147 × 38 × 27 mm bar explicitly identified in the paper-character example. The RGBW catalog suffix lists individual colour options; this kit selects red.
$109.00In proposed setupカメラOur pickMV-CS050-10GM(NPOE)
5 MP monochrome global-shutter camera proposed for a contrast trial. Confirm field, sampling, exposure and algorithm on the actual application.
$819.00In proposed setupレンズOur pickLS-KF1628M-ML
Proposed 16 mm C-mount macro lens at its printed 0.1x magnification / 152 mm working-distance pair. The proposed 2448 × 2048 sensor with 3.45 µm pixels gives a derived 84.456 × 70.656 mm field; confirm focus, coverage and residual distortion on the real sample.
$319.00In proposed setupCamera test stationOur pickLS-BT-XZ-G-6-6045
600 mm column, 600 × 450 mm breadboard, XZ adjustment, glass tray and two lighting holders as listed. Proposed bench fixture; confirm loads, travel and camera/lens clamps.
$359.00In proposed setup"Tested" identifies the part named in the source. "Our pick" is a proposed alternative or supporting part. The quote includes only cards marked "In proposed setup", with the quantities shown; other test arrangements are separate. Confirm colour, optics, controllers, power supplies, cables and mounting before ordering.
About this case study: the photos and camera images come from the application laboratory of the maker of the lighting and optics we sell, imaged on the parts shown; your results depend on your part, camera and set-up. This is an application-lab study, not a LumaSpec customer deployment. Source figures are reported results; proposed components require a fresh trial. The 3D scene illustrates the arrangement and does not simulate imaging performance.
More case studies
Packaging traceability · Code imaging
UV bottle-cap code imaging
Prove the UV image first, then measure the reader performance.
- Method365 nm UV ring illumination
- EvidenceReal application-lab capture
High-speed inspection development · Positioning
Metal positioning with short-exposure strobe lighting
A short exposure needs a verified light-and-trigger recipe before it becomes a motion-freezing claim.
- MethodStrobe coaxial white light
- EvidenceReal application-lab capture
Packaging traceability · Date-code imaging
Dot-printed date-code contrast
Keep dots separate in the image before evaluating a date reader.
- Light in sourceLS-2BS23738-RGBW · blue
- EvidenceReal application-lab image
Start with your inspection requirement
Make the next trial specific.
Tell us the part size, smallest defect or tolerance, available working distance, material and line speed. Include what a good part and a reject look like.
Discuss your applicationシステム構成