Linear Scratch Module

The Linear Scratch module uses the 45° circumferential light source and observer camera to detect and quantify linear and small-area defects—such as scratches, dents, streaks and contamination—that are visible under normal viewing conditions, for example in a laboratory light booth or typical office lighting. It turns what would normally be a subjective visual check under standard room lighting into clear numerical indicators that can be trended, compared and specified.

Purpose of this module

  • Identify and measure linear and local defects that reduce perceived surface quality in everyday viewing environments, not just under extreme or artificial inspection lighting.
  • Provide process feedback so you can compare cleaning, coating and handling steps, and set objective pass/fail limits for scratches, dents, streaks and visible contamination.

How defects are detected

  • The module uses a 45° circumferential light source to illuminate the surface uniformly from all directions at 45°, closely mimicking common overhead and light‑booth conditions while enhancing the visibility of defects.
  • A camera observes the same area and captures high‑resolution images in which scratches, dents, streaks and contaminants appear as local changes in brightness, relative to the surrounding surface.
  • Image‑processing algorithms then separate these defect features from the normal background appearance, classify them by type and geometry, and calculate parameters such as length, area, count and visibility.

Directional categorisation: horizontal and vertical scratches

Detected linear features are further analysed by their orientation on the surface and automatically classified as predominantly horizontal or vertical scratches.

By comparing the total length, area and count of horizontal versus vertical scratches, the Aesthetix can reveal inhomogeneity or directional damage, for example abrasion caused by a process step that acts mainly in one direction (such as machine polishing, wiping or conveyor contact).

This directional information helps users diagnose root causes more quickly, adjust process settings (tool paths, wiping direction, handling fixtures) and verify that corrective actions have reduced directional scratching rather than simply changing its orientation.

Role of sensitivity

  • A Sensitivity control adjusts how strongly the detection algorithm responds to subtle defect features in the images.
  • At low sensitivity, only the most obvious scratches and defects are reported, corresponding to marks that are clearly visible under normal office or light‑booth conditions.
  • At medium sensitivity, the module reveals finer streaks, lighter scratches and small contamination spots that may be noticed by trained inspectors or under slightly more critical viewing.
  • At the highest sensitivity, all visible linear and local features are highlighted, including faint defects that may only be noticed under very critical inspection, while still being evaluated within a normal‑lighting context.

What this module measures

  • Length parameters (total, vertical and horizontal) describe how extensive linear defects such as scratches and streaks are, and whether they are predominantly oriented in one direction.
  • Area parameters quantify how much of the measured region is covered by detected defects (scratches, dents, contamination), again split into total, vertical and horizontal components where applicable.
  • Count parameters report how many individual defect features are present for each orientation or class, giving a simple defect density measure.
  • Visibility parameters express how noticeable these defects are under typical viewing conditions, combining their size, brightness and contrast into perception‑based values.

How to use this module in practice

  • Use lower sensitivity settings and the visibility parameters to set realistic acceptance criteria that reflect what customers and end‑users see in laboratory booths, offices or showrooms.
  • Increase sensitivity when you need to diagnose underlying quality issues, compare alternative process steps, or ensure that a premium surface remains visually clean and uniform under more critical inspection.
  • Trend defect metrics over time or between batches to confirm that surface preparation, coating, polishing and handling processes are stable, and that any changes in materials or equipment do not introduce new visible defects.