25 Jan, 2019
We extend the range of camera settings of ace camera series with new, powerful features – Vignetting Correction, which allows a correction of edge shadowing when the image circle is too small in relation to the sensor size.
High-performance, effective, useful – the three new ace features:
- Vignetting Correction
- PGI for monochrome cameras
- Stacked ROI (selection of multiple ROIs (Regions of Interest))
How do these features work, what benefits and advantages do they offer and in which camera models are they available?
Vignetting Correction (patent pending)
Vignetting is a well-known phenomenon in image processing and describes the decrease in image brightness towards the edge. This often results in this effect:
If the image circle of the lens used is too small in relation to the camera sensor, this effect can manifest strongly and affect the image quality accordingly. Details at the edge of the sensor can often only be inspected poorly, or not at all or the inspection is made more difficult by the different brightness values across the image. In many cases, the choice of a larger lens – for example from 2/3″ to 1″ – can help. However, this solution is usually associated with higher costs.
If one compares the standard available optics with the current variety of sensor sizes, the imbalance becomes clear.
This imbalance affects, for example, the following sensor-lens combination:
The new Vignetting Correction feature provides effective support here:
Thanks to Vignetting Correction, there is no negative effect on the frame rate or image quality after a one-time calibration of the camera, since the correction values are stores in the camera and automatically taken into account in the image output. For example, users can combine ace cameras with Sony IMX304 or IMX253 sensors with their 1.1″ format with 1″ lenses without having to accept any edge shadowing. It is no longer necessary to switch to a lens with a larger image circle.
The Vignetting Correction feature is available for selected ace U and ace L models with GigE and USB 3.0 interfaces.
Attractively priced combinations of Basler cameras and lenses with Vignetting Correction:
|Camera||Interface||Sensor||Sensor Size||Lens Fit|
|acA4112-20uc||USB 3.0||IMX 304||1.1″||1″|
PGI for Monochrome Cameras
Since its introduction, the PGI feature set has been in high demand, facilitating color applications for many customers and even making some previously unavailable applications possible. This successful combination of 5×5 Debayering, Color-Anti-Aliasing, Denoising, and Improved Sharpness was only available for color cameras until now. Now an adapted form of PGI is available for the world of gray-scale values.
Optimized for monochrome requirements
Debayering and color-anti-aliasing are not relevant for monochrome cameras – but noise reduction and increased image sharpness certainly have benefits. Basler has now adjusted the PGI algorithm exactly for these requirements.
In contrast to color cameras, a debayered pixel format is not required for monochrome cameras. As a result, raw images can be used and the maximum sensor speed can be utilized.
Due to its mode of operation, a color camera will show noise and other effects more strongly than a monochrome camera. This means that the positive effect of using the PGI feature set can be seen more clearly in color cameras than in monochrome cameras. Take this into account when testing.
The PGI feature set for monochrome cameras is available for the entire ace L product line and all ace U models with Pregius sensors from Sony and with PYTHON sensors from ON Semiconductor.
Stacked ROI: Selection of Multiple Regions of Interest
Using a region of interest (ROI) to increase speed or reduce the data load is a proven and often-used method in industrial image processing. But as a result of increasing resolutions, not all important characteristics are located close to each other, which limits the benefits of ROI. However, a higher speed and/or a reduction of the data volume is still necessary in many cases in order to implement an application economically.
This becomes clear with the example of an application for bottle inspection. Here the focus of the inspection is often limited to
- the bottle neck for a check of the fill level and closure,
- the label in the center of the bottle to check the exact positioning and graphic correctness and
- the bottom to check for fissures or cracks.
These inspection machines keep getting faster in order to handle increasing cycle speeds. At the same time, the camera resolution and thus the data volume per image are constantly growing so that more details can be recognized and a higher-quality inspection can be performed. This leads to increasing demands on the applied processors and algorithms to be able to process this amount of data at all.
With the help of the new Stacked ROI feature, the focus in an application can now be directed to multiple ROIs at the same time, as illustrated by the sample case described in figure 2.
Basler offers the feature integrated in the FPGA for all ace U and ace L models with PYTHON sensors from ON Semiconductor and the fast Sony Pregius sensors (IMX174, IMX252, IMX250, IMX255, IMX253). It includes the use of up to eight (four for the IMX174) stacked zones which are adjustable in height (see figure 3).