Measure printed line and character quality objectively from a flatbed scan. Line width, raggedness, blurriness and character darkness with algorithms based on ISO/IEC 24790. Including scanner calibration functionality to improve repeatability between different labs and scanners.
PapEye Line Quality is user-friendly software designed to help paper, board and print professionals assess printed line and character quality according to the ISO/IEC 24790 standard. Using a standard flatbed scanner, you can quickly analyse printed lines and obtain objective measurements for attributes that would otherwise be judged visually under magnification.
The application analyses each line that crosses user-drawn analysis regions and reports a separate row of results for each detected line crossing the analysis region top/bottom or left/right edges. Measured line boundaries are drawn directly over the scanned image, making it easy to verify which edges and transitions produced each result.
PapEye Line Quality is a standalone Windows application. Licenses are sold as permanent licenses for a single PC. A list of recommended scanners is available from Tapio Measurement Technologies.
PapEye Line Quality measures four key attributes of line quality. Together, they describe the dimensions, edge consistency, sharpness and darkness of printed lines and character strokes.
| Attribute | What it tells you |
|---|---|
| Line width | The edge-to-edge distance at the R40 reflectance threshold, reported in micrometres. |
| Raggedness | How far each printed edge deviates from an ideal straight line, reported in micrometres. |
| Blurriness | The width of the edge transition between the R70 and R10 boundaries, normalised according to the line’s optical density. |
| Character darkness | The optical density inside the printed line, scaled according to the square root of its width in millimetres. |
PapEye draws the detected measurement boundaries directly over the scanned line. This provides a visual check that the software measured the intended edge and helps explain how each reported value was produced.
The selected scan and measurement region must contain enough information around the printed line for its edges and background to be measured reliably. PapEye reports warnings when the recommended measurement conditions are not met.
| Item | Requirement |
|---|---|
| Scan resolution | 1200 DPI is recommended for the analysis. Lower resolutions can be measured, but the result is flagged. |
| Line length | At least 1 mm. A length of 5 mm or more along the line is recommended. |
| Region across the line | The line width plus approximately 2 mm is recommended, providing at least 1 mm of clean paper on each side of the line. |
| Line orientation | The line should be within 30 degrees of vertical or horizontal. |
| Lines per region | Up to 50 lines can be measured in one selected region. |
PapEye Line Quality provides two forms of scanner calibration. Reflectance calibration, or OECF, corrects the scanner’s tonal response. MTF compensation measures and corrects the blur introduced by the scanner optics. Near-horizontal and near-vertical edges are calibrated separately because a scanner can have different sharpness in its two scan directions.
| Operating system | Windows |
| Application | Standalone executable with no conventional installation required |
| Licensing | Permanent license for PapEye Print Uniformity on a single PC |
| Input formats | PNG, JPEG, GIF, BMP, TIFF and PDF |
| Result exports | CSV and Excel-compatible exports, result thumbnails and sample-region files |
| Batch processing | Analysis and export of entire folders containing similar samples |
| Command line | Available for automated and scripted analysis |
Licenses are issued per PapEye product and per machine. A license for one PapEye product does not unlock another product. On first run, PapEye displays a Machine ID. Send the Machine ID to Tapio Measurement Technologies and place the returned license file in the .papeye folder in the home directory of the user.
Not necessarily. If you are comparing similar samples measured with the same scanner, resolution and scanner settings, calibration may not be required. The scanner contributes approximately the same optical blur to every measurement, so the results can still be used reliably for comparative analysis, sample ranking and process monitoring.
To calibrate the scanner, scan a slanted-edge and grayscale target and use the calibration features in settings or PapEye Line Quality
The most common reasons are that the line does not cross the complete selected region, stops inside the region, is more than 30 degrees away from vertical or horizontal, or does not have enough clean paper beside it.
Depending on the required accuracy, we recommend using 1200 DPI or higher. Lower-resolution scans can also be measured in the software.
The measured attributes apply to sufficiently long, straight line segments, which is how the ISO/IEC 24790 standard defines the measurement.
To analyse a character, draw the measurement region across a suitable straight stroke that crosses the complete region.
Character darkness represents how solidly a printed line or character stroke is laid down.
PapEye calculates the average optical density inside the line’s R25 boundary and scales it according to the square root of the line width in millimetres. This makes the result more comparable between printed strokes of different widths.
Measure line width, raggedness, blurriness and character darkness from standard flatbed scanner images. Contact Tapio Measurement Technologies to request a demonstration, discuss your measurement application or receive a quote.