Comparison Profile
Enhancements
Ignore invisible elements
The GUI documentation for //Ignore invisible elements// describes the current profile sidebar of i-net PDFC. The option belongs to the Enhancements group. The Compute actual visibility sub-option is shown and enabled only when Ignore invisible elements is active.
Raw profile values
The filter is enabled by adding the identifier INVISIBLEELEMENTS to the comma-separated FILTERS list. The default value of the FILTERS property contains INVISIBLEELEMENTS,TEXTTRANSFORM,SOLVEFALSEREPLACE. The related profile property is:
| Raw key | Value or range | Meaning and default |
|---|---|---|
FILTERS | contains INVISIBLEELEMENTS | Enables the heuristic for elements that do not contribute to the visible result. The list can contain additional filter identifiers. |
COMPUTE_CLIPPING | true or false | Enables structural computation of actual visibility. The default value is false. |
Current heuristic
With COMPUTE_CLIPPING=false, InvisibleObjectsFilter uses element-based heuristics on extracted PDF elements instead of rendering the page as pixels. Among other cases, it removes the following from the comparison basis:
- elements outside the page bounds or their clipping area
- text and shapes without visible fill or stroke
- zero-size images and very small line or curve differences
- duplicate comparable elements
- transparent or white content on a blank background
Structural elements and annotations are retained. Images are not removed as duplicates. White elements over colored content are retained; white text may be restricted to the actually colored area. The exact effect depends on the structure of the PDF document.
Compute actual visibility
With COMPUTE_CLIPPING=true, i-net PDFC uses ClippingProcessor.computeClipping. The calculation considers page bounds, PDF clipping paths, occlusion, and the drawing order of extracted elements. Hidden portions of shapes and text are cropped, fully covered elements are removed, compatible shapes are merged, and white content is removed only on a blank background. Images are cropped only when the visible area is rectangular.
This option replaces the standard heuristic with a more precise structural visibility calculation, while still operating on extracted PDF elements rather than rendered pixels.
Mapping to the current profile sidebar
The current UI keys and their raw profile values are:
| Sidebar option | Structure or UI key | Raw profile value |
|---|---|---|
| Ignore invisible elements | pdfc.filter.invisible_elements_filter | FILTERS contains INVISIBLEELEMENTS |
| Compute actual visibility | pdfc.filter.invisible_elements_filter.clipping | COMPUTE_CLIPPING |
Both options are provided by the current ProfileUIBuilder extension. The second option is visible and enabled only when the first option is active.
Profile fragment
A possible XML profile fragment is:
<entry key="FILTERS">INVISIBLEELEMENTS</entry> <entry key="COMPUTE_CLIPPING">false</entry>
Set the second value to true for structural visibility calculation.
Limits and performance
The element-based heuristic can suppress intentional white, transparent, duplicate, or very small content. Clipping calculation can considerably increase comparison time and memory use, especially on pages with many overlapping shapes. Complex transparency and irregular image clipping are handled conservatively. Neither variant is a complete rendering or accessibility check.
