CMOS Archives - 1stVision Inc. - Machine Vision Articles

January 16, 2023January 23, 2023

SONY IMX548 now in Alvium CSI-2, USB3, 5GigE cameras

AVT Alvium housed, board-level, and open options

Allied Vision has integrated the IMX548 into the Alvium family with the Alvium C/U/G5-511 camera models, where the prefix designator:

C is CSI-2, the Camera Serial Interface, popular for embedded systems
U is USB3, the widely available interface between computers and electronic devices
G5 is 5GigE, with up to 100 meter cable runs and 5x the throughput of GigE

SONY’s IMX548 is a member of the 4th generation Pregius sensors, providing global shutter for active pixel CMOS sensors, with low-noise structure yielding high-quality images. See our illustrated blog for an overview of Pregius-S‘ back-illuminated sensor structure and its benefits.

So why the IMX548 in particular? Readers who follow the sensor market closely may note that the IMX547 looks the same in terms of pixel structure and resolution. Correct! SONY found they could adapt the sensor to a smaller and more affordable package, passing those savings along to the camera manufacturer, and in turn to the customer. As 5.1MP resolution is the sweet spot for many applications, Allied Vision picked up on SONY’s cues and integrated the IMX548 into the Alvium family.

There are nuanced timing differences between the IMX547 and IMX548. For new design-ins, this is of no consequence. If you previously used the IMX547, please check with our sales engineers to see if switching to the IMX548 requires any adjustments – or if it’s simply plug-and-play.

As shown in the photo above, Alvium cameras are very compact, and the same sensor and features are offered in housed, board-level, and open configurations. AVT Alvium is one of the most flexible, compact, and capable camera families in the current market.

Concurrent with the release of this new sensor in the Alvium camera family, Allied Vision has also released Alvium Camera Firmware V 11.00, notably adding the following features:

Sequencer
Counters
Input Line Debouncer
Action Commands
Flow Control
Burst Mode

1st Vision’s sales engineers have over 100 years of combined experience to assist in your camera and components selection. With a large portfolio of lenses, cables, NIC card and industrial computers, we can provide a full vision solution!

August 23, 2022August 23, 2022

Sony Pregius 4th generation continues image sensor excellence

Continuing the tradition of excellence begun in 2013, Sony’s 4th generation of Pregius sensors, designated Pregius S, is now available in a range of cameras. All Pregius sensors, starting with the “IMX” code preceding the sensor model number, provide global shutter pixel technology for active pixel CMOS image sensors that adopts Sony Semiconductor Solutions Corporation’s low-noise structure to realize high-quality images.

Pregius S brings a back-illuminated structure, enabling smaller sensor size as well as faster frame rates. The faster frame rates speak for themselves, but it’s worth noting that the smaller sensor size has the benefit of permitting smaller lenses, which can reduce overall costs.

**Figure 1. Surface-illuminated vs. Back-illuminated image sensors**

Let’s highlight some of the benefits offered by Pregius S image sensors:

With the photodiode placed closer to the micro-lens, a wider incident angle is created, admitting more light, leading to enhanced sensitivity. At low incident angles, the Pregius S captures up to 4x as much light as Sony’s own highly-praised 2nd generation Pregius sensors from just a few years ago! (See Fig. 1 above)
Light collection is further enhanced by positioning wiring and circuits below the photodiode
Smaller 2.74um pixels provides higher resolution in typical smaller cube cameras, continuing the evolution of ever more capacity and performance while occupying less space

While Pregius S sensors are very compelling, the prior generation Pregius sensors remain an excellent choice for many applications. As with many engineering choices, it comes down to performance requirements as well as cost considerations, to achieve the optimal solution for any given application. Many of the Pregius S image sensors can be found in industrial cameras offered by 1stVision. Use our “Sensor” pull down menu on our camera selector to look for the new sensors, starting with IMX5 e.g. IMX541.

1st Vision’s sales engineers have over 100 years of combined experience to assist in your camera selection. With a large portfolio of lenses, cables, NIC card and industrial computers, we can provide a full vision solution!

Graphics courtesy of Sony.

October 12, 2021October 13, 2021

Spatial resolution is an essential machine vision concept

Spatial resolution is determined by the number of pixels in a CMOS or CCD sensor array. While generally speaking “more is better”, what really matters is slightly more complex than that. One needs to know enough about the dimensions and characteristics of the real-world scene at which a camera is directed; and one must know about the smallest feature(s) to be detected.

Choosing the right sensor requires understanding spatial resolution

The sensor-coverage fit of a lens is also relevant. As is the optical quality of the lens. Lighting also impacts the quality of the image. Yada yada.

But independent of lens and lighting, a key guideline is that each minimal real-world feature to be detected should appear in a 3×3 pixel grid in the image. So if the real-world scene is X by Y meters, and the smallest feature to be detected is A by B centimeters, assuming the lens is matched to the sensor and the scene, it’s just a math problem to determine the number of pixels required on the sensor.

There is a comprehensive treatment how to calculate resolution in this short article, including a link there to a resolution calculator. Understanding these concepts will help you to design an imaging system that has enough capacity to solve your application, while not over-engineering a solution – enough is enough.

Finally, the above guideline is for monochrome imaging, which to the surprise of newcomers to the field of machine vision, is often more better than color, for effective and cost-efficient outcomes. Certainly some applications are dependent upon color. The guideline for color imaging is that the minimal feature should occupy a 6×6 pixel grid.

If you’d like someone to double-check your calculations, or to prepare the calculations for you, and to recommend sensor, camera and optics, and/or software, the sales engineers at 1stVision have the expertise to support you. Give us some brief idea of your application and we will contact you to discuss camera options.

1st Vision’s sales engineers have an average of 20 years experience to assist in your camera selection. Representing the largest portfolio of industry leading brands in imaging components, we can help you design the optimal vision solution for your application.

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1st Vision is the most experienced distributor in the U.S. of machine vision cameras, lenses, frame grabbers, cables, lighting, and software in the industry.

April 9, 2021April 9, 2021

Keys to Choosing the Best Image Sensor

Image sensors are the key component of any camera and vision system. This blog summarizes the key concepts of a tech brief addressing concepts essential to sensor performance relative to imaging applications. For a comprehensive analysis of the parameters, you may read the full tech brief.

Download Tech Brief - Choosing the Best Image Sensor

While there are many aspects to consider, here we outline 6 key parameters:

Physical parameters

Resolution: The amount of information per frame (image) is the product of horizontal pixel count x by vertical pixel count y. While consumer cameras boast of resolution like car manufacturers tout horsepower, in machine vision one just needs enough resolution to solve the problem – but not more. Too much resolution leads to more sensor than you need, more bandwidth than you need, and more cost than you need. Takeaway: Match sensor resolution to optical resolution relative to the object(s) you must image.

Aspect ratio: Whether 1:1, 3:2, or some other ratio, the optimal arrangement should correspond to the layout of your target’s field of view, so as not to buy more resolution than is needed for your application.

Frame rate: If your target is moving quickly, you’ll need enough images per second to “freeze” the motion and to keep up with the physical space you are imaging. But as with resolution, one needs just enough speed to solve the problem, and no more, or you would over specify for a faster computer, cabling, etc.

Optical format: One could write a thesis on this topic, but the key takeaway is to match the lens’ projection of focused light onto the sensor’s array of pixels, to cover the sensor (and make use of its resolution). Sensor sizes and lens sizes often have legacy names left over from TV standards now decades old, so we’ll skip the details in this blog but invite the reader to read the linked tech brief or speak with a sales engineer, to insure the best fit.
Quantum Efficiency and Dynamic Range:

Quantum Efficiency (QE): Sensors vary in their efficiency at converting photons to electrons, by sensor quality and at varying wavelengths of light, so some sensors are better for certain applications than others.

Dynamic Range (DR): Factors such as Full Well Capacity and Read Noise determine DR, which is the ratio of maximum signal to the minimum. The greater the DR, the better the sensor can capture the range of bright to dark gradations from the application scene.
Optical parameters
While some seemingly-color applications can in fact be solved more easily and cost-effectively with monochrome, in either case each silicon-based pixel converts light (photons) into charge (electrons). Each pixel well has a maximum volume of charge it can handle before saturating. After each exposure, the degree of charge in a given pixel correlates to the amount of light that impinged on that pixel.
Rolling vs. Global shutter
Most current sensors support global shutter, where all pixel rows are exposed at once, eliminating motion-induced blur. But the on-sensor electronics to achieve global shutter have certain costs associated, so for some applications it can still make sense to use rolling shutter sensors.
Pixel Size
Just as a wide-mouth bucket will catch more raindrops than a coffee cup, a larger physical pixel will admit more photons than a small one. Generally speaking, large pixels are preferred. But that requires the expense of more silicon to support the resolution for a desired x by y array. Sensor manufacturers work to optimize this tradeoff with each new generation of sensors.
Output modes
While each sensor typically has a “standard” intended output, at full resolution, many sensors offer additional switchable outputs modes like Region of Interest (ROI), binning, or decimation. Such modes typically read out a defined subset of the pixels, at a higher frame rate, which can allow the same sensor and camera to serve two or more purposes. Example of binning would be a microscopy application whereby a binned image at high speed would be used to locate a target blob in a large field, then switch to full-resolution for a high-quality detail image.

For a more in depth review of these concepts, including helpful images and diagrams, please download the tech brief.