Contrast Distortion Filter

The Contrast Distortion filter corrects and/or removes points that are affected by contrast distortion as a result of blurring in the camera lens. In the point cloud, this typically occurs in regions with high contrast (strong specular reflection), and in regions with large texture gradients.

The filter has two modes; correction and removal. How much a point is corrected in 3D space depends on the strength parameter. If removal is on, points experiencing large corrections will be removed if the correction is above the threshold parameter value. Both correction and removal can be turned on and off.

The filter works best when aperture values are chosen such that the camera has a good focus (see Depth of Focus for adjusting aperture accordingly). The higher the strength value is, the further are the points corrected. The higher the threshold value is, the stricter the filter is on removing points.

Caution

Contrast Distortion filter can overcompensate correction if strength is set too high!

When do you use the Contrast Distortion filter?

Correction

In applications such as bin picking, it is common to use matching algorithms based on models for object detection and localization. Using the correction component of this filter can make the resulting point cloud of an object better resemble the actual object and its CAD model.

Removal

In inspection applications, it is often desired to keep only the points with high confidence. Points affected with the contrast distortion are considered to have low confidence. The removal component of this filter can be used to remove these points.

Note

Contrast Distortion filter adds the following processing time per 3D capture:

Expected median (±stddev) in ms

Filter	Zivid One+			Zivid Two
	Intel UHD 750	Intel UHD G1	NVIDIA 3070	Intel UHD 750	Intel UHD G1	NVIDIA 3070
	High-end [1]	Low-end [2]	High-end [3]	High-end [1]	Low-end [2]	High-end [3]
Contrast Distortion Correction	57 (±2) ms	96 (±2) ms	7 (±0.6) ms	58 (±1) ms	99 (±410) ms	7 (±0.8) ms
Contrast Distortion Removal	40 (±2) ms	60 (±3) ms	4 (±0.6) ms	41 (±1) ms	61 (±435) ms	5 (±0.9) ms

[1] (1,2)

High-end machine with GPU: Intel UHD Graphics 750 (ID:0x4C8A) and CPU: 11th Gen Intel(R) Core(TM) i9-11900K @ 3.50GHz, 10GbE

[2] (1,2)

Low-end machine with GPU: Intel UHD Graphics G1 (ID:0x8A56) and CPU: Intel(R) Core(TM) i3-1005G1 CPU @ 1.20GHz, 1GbE

[3] (1,2)

High-end machine with GPU: NVIDIA GeForce RTX 3070 and CPU: 11th Gen Intel(R) Core(TM) i9-11900K @ 3.50GHz, 10GbE

Version History

SDK	Changes
2.0.0	Contrast distortion filter API is added.