CCD vs CMOS industrial cameras – Learn how CMOS image sensors excel over CCD!

CMOS Image sensors used in machine vision industrial cameras are now the image sensor of choice! But why is this?

Allied Vision conducted a nice comparison between CCD and CMOS cameras showing the advantages in the latest Manta cameras.

Until recently, CCD was generally recommended for better image quality with the following properties:

High pixel homogeneity, low fixed pattern noise (FPN)
Global shutters for machine vision applications requiring very short exposure times

Where in the past, CMOS image sensors were used due to existing advantages:

High frame rate and less power consumption
No blooming or smear image artifacts contrary to CCD image sensors
High Dynamic Range (HDR) modes for acquisition of contrast rich and extremely bright objects.

Today CMOS image sensors offer many more advantages in industrial cameras versus CCD image sensors as detailed below

Overall key advantages are better image quality than earlier CMOS sensors due to higher sensitivity, lower dark noise, spatial noise and higher quantum efficiency (QE) as seen in the specifications comparing a CCD and CMOS camera.

Sony ICX655 CCD vs a Sony IMX264 CMOS sensor

Comparing the specifications between CCD and CMOS industrial cameras, the advantages are clear.

Higher Quantum Efficiency (QE) – 64% vs 49% where higher is better in converting photons to electrons.
Pixel well depth (ue.sat: ) – 10613 electrons (e-) vs 6600 e- where a higher well depth is beneficial
Dynamic range (DYN) – Where CMOS provides almost +17 dB more dynamic range. This is a partial result of the pixel well depth along with low noise.
Dark Noise: CMOS is significantly less vs CCD with only 2 electrons vs 12!

Images are always worth a thousand words! Below are several comparison images contrasting the latest Allied Vision CMOS industrial cameras vs CCD industrial cameras.

Dynamic Range of today’s CMOS image sensors are contributed to several of the characteristics above and can provide higher fidelity images with better dynamic range and lower dark noise as seen in this image comparison of a couple of electronics parts

The comparison above illustrates how higher contrast can be achieved with high dynamic range and low noise in the latest CMOS industrial cameras

High noise in the CCD image causes low contrast between characters on the integrated circuit, whereas the CMOS sensor provides higher contrast.
Increased Dynamic range from the CMOS image allows darker and brighter areas in an image to be seen. The battery (left part) is not as saturated vs the CCD image allowing more detail to be observed.

Current CMOS image sensors eliminate several artifacts and provide more useful images for processing. The images below are an example of a PCB with LEDs illuminated imaged with a CCD vs CMOS industrial camera

CMOS images will result in less blooming of bright areas (LED’s for example in the image), smearing (vertical lines seen in the CCD image) and lower noise (as seen in the darker areas, providing higher overall contrast)

Smearing (vertical lines seen in the CCD image) are eliminated with CMOS. Smear has inherently been a bad artifact of CCDs.
Dynamic Range inherent to CMOS sensors allow the LED’s to not saturates as much as the CCD allowing more detail to be seen.
Lower noise in the CMOS image, as seen in the bottom line graph shows a cleaner image.

More advantages of new CMOS image sensors include:

Higher frame rates and shutter speeds over CCD resulting in less image blur in fast moving objects.
Much lower cost of CMOS sensors translate into much lower cost cameras!
Improved global shutter efficiency.

CMOS image sensor manufacturers are also working to design sensors that easily replace CCD sensors making for an easy transition which results in lower cost and better performance. Allied Vision has several new cameras replacing current CCD’s with more to come! Below are a few popular cameras / image sensors that have been recently crossed over to CMOS image sensors

Sony ICX424 and Sony ICX445 (1/3″ sensor) found in the Manta G-032 and Manta G-125 cameras are now replaced by the Sony IMX273 in the Manta G-158 camera keeping the same sensors size. (Read more here)

Sony ICX424 (1/3″sensor), can also be replaced by the Sony IMX287 (1/2.9″ sensor) with pixel sizes of 6.9um closely matching the older IMX424 having 7.4um pixels. Allied Vision Manta G-040 is a nice solution with all the benefits of the latest CMOS image sensor technology. View the short videos below for the highlights.

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!

Allied Vision Manta G-040 & G-158 provide great replacements to legacy CCD cameras

Upgrade your 5MP CCD (Sony ICX625) camera for higher performance with an Allied Vision Mako G-507 (IMX264)

April 25, 2018April 26, 2018

3-CMOS machine vision cameras bring color fidelity to the market at half the price as previous models

Single sensor machine vision cameras use a mosaic filter placed on the sensor to create color images. This is also called a ‘Bayer’ filter, named after the person who invented it. However, color images from this filter lose resolution and color fidelity compared to ‘true’ color images. Spatial resolution is lost due to interpolation, while the Bayer filter pattern reduces true color representation, sensitivity and dynamic range. To overcome these issues, multi-sensor (3-CCD / 3-CMOS) machine vision cameras can be used.

Typically, machine vision 3-CCD cameras were high cost, until now with CMOS sensors becoming the leading image sensor technology. Now, machine vision 3-CMOS machine cameras provide major benefits over Bayer cameras and at more attractive entrance cost.

CMOS sensor technology has lowered the price of 3 image sensor cameras by 50% providing a better alternative to Bayer color cameras for many applications. JAI’s Apex Series 3-CMOS cameras are the game changer for demanding color applications.

Watch this video to learn more about 3-CCD/3-CMOS cameras

Machine Vision 3-CMOS cameras Vs Bayer cameras provide major benefits for color applications

Better color precision – Accurate RGB values are obtained for each pixel so there is no interpolation/estimation of colors as found in Bayer cameras. This can be critical for paint/ink matching, printing inspection systems, digital pathology, or other applications where color values must be extremely accurate.

Better spatial resolution – The Bayer interpolation process also tends to blend edges and small details. While this can be pleasing to the eye, it can make spatial measurements or bar code reading imprecise or error prone, causing the use of more expensive high resolution Bayer cameras or requiring a second monochrome camera for imaging these details

Higher sensitivity – The prism glass in the AP-3200T-USB and associated cameras, has better light transmission properties than the polymer filters in a standard Bayer sensor. This enables more light to reach the pixels for better overall sensitivity and lower lighting requirements.

Lower noise, higher dynamic range – White balancing on a JAI prism camera can be done on individual channels with shutter adjustments instead of adding gain to the image. This results in lower noise and higher usable dynamic range.

What about “improved” Bayer capabilities like 5×5 interpolation?

Several camera manufacturers claim vastly improved capabilities for color imaging, including 5×5 de-Bayering, color-anti-aliasing, denoising
and improved sharpness. But consider the following: 5×5 interpolation
means you are using an even larger area within the image to estimate each pixel’s color value. So while this can do a better job of “smoothing” color transitions to the eye, it can actually result in less-precise color values for image processing, especially where color variation is high.

This is illustrated in the following images, under identical conditions, by a camera with 5 x 5 debayering and a JAI Apex 3-CMOS camera. The CIE L*a*b* reference chart provides a set of exact color values when expected under specified lighting conditions. The result: 5×5 debayering results in 40% out of match to the expected colors vs 13% for the JAI Apex 3-CMOS camera!

More advanced color imaging features

JAI’s Apex 3-CMOS machine vision cameras provide additional advanced features aside from excellent color fidelity and highlighted as follows:

Color Space conversion: Color data from the camera can be provided using built in conversions to several color spaces including sRGB, Adobe RGB, CIE XYZ and HSI. Custom RGB conversions can also be done using the cameras color matrix circuit.
Color Enhancer Function: Allows the 3-CMOS cameras to “boost” the intensity of 6 colors to help features stand out, such as the red color of blood vs surrounding tissue in a medical application. Additionally, degree’s of edge enhancement can be to increase the contrast of color boundaries.
Color Binning: While most Bayer cameras do not offer this, due to the prism architecture of the 3-CMOS cameras, you can easily bin pixels by 1×2, 2×1 and 2×2 to increase sensitivity, reduce shot noise and / or increase the frame rate.
Color temperature presets from 3200K, 5000K, 6500K and 7000K

All of these features, along with reduced costs for 3-CMOS color cameras, now make this a very attractive solution for demanding color applications! Applications in eye diagnostics, pathology, surgical imaging, meat/food inspection, print inspection and automotive color matching are a few that would highly benefit from the JAI Apex 3-CMOS camera series.

Need to proof 3-CMOS / 3-CCD prism based cameras will enhance your application? Let’s discuss sending you a demo camera!

Currently there are 6 new CMOS models outlined below and full specifications can be found HERE.

1st Vision is the leading provider of industrial imaging components with over 100 years of combined imaging experience. Do not hesitate to contact us regarding the new prices of the 3-CMOS cameras!

Be sure to visit our related blogs on 3-CCD and Prism based cameras

How does a 3CCD camera improve color accuracy and spatial resolution versus standard Bayer color cameras?

White Paper – Learn about High Dynamic Range (HDR) Imaging techniques for Machine Vision

White Paper -How does prism technology help to achieve superior color image quality?

April 25, 2018April 25, 2018

The Machine Vision camera “Sleepability factor”!?

The sleepability factor, or how saving $50 on a machine vision camera could cost you thousands!

As an independent machine vision camera distributor, we are asked about the manufacturers we represent. Out of all them, we have chosen to only carry products from a few machine vision camera and lens companies of which we have not really changed this over the 20 years we have been in business. Why is this?

These days, there are probably over 30 different camera manufacturers making products for the machine vision marketplace, many using the identical image sensors. Considering anyone can just put up a web page and start selling, how can a user know which product to purchase? Are there really any differences? Should I just purchase on price? Should I buy from a distributor or from the manufacturer direct? All great questions, that we will attempt to answer.

The very simple and quick answer is that if you just need to get a image in good light, pretty much any camera from any vendor will do that job. No matter if it is from a large company or a 2 person startup, when you take the product out of the box, you should see a “good” image.

But if you said, “I want this camera to run 24/7 for the next 5 years, I want to be able to develop complex software to integrate into my machine, I need the image sensor plane to be within a certain tolerance for each machine,” this changes the situation.

IDS imaging camera — IDS Imaging USB3 cameras

The reason we have chosen the camera manufacturers we sell products from is because each of them has a proven track record of reliability. Each of the companies we represent ships 6 figures of cameras per year. IDS Imaging for instance ships close to 200,000 cameras per year and has a return rate of under 0.3%.

Allied vision camera — Allied Vision GigE Cameras

Allied Vision was the first company to incorporate the Precision Timing Protocol (PTP) which allows for precise multi camera sync, enabling our clients to not only make sure the application will work, but it doesn’t take years to develop it.

Dalsa line scan cameras — Teledyne Dalsa Line Scan cameras

Teledyne Dalsa, besides being a leader in line scan technology, has a SDK that has been built upon for over 30 years.

JAI’s prism technology is so good that its competitors actually have JAI

manufacture for them. This isn’t to say there aren’t other camera companies with such characteristics. There are, and many of the other camera companies have excellent products as well. It is just that we have chosen these companies, and we have stood with them for 15+ years for good reasons… sleepabilty!

What does this mean to you as a client? Yes, you can purchase a camera from any vendor, which on a $500 camera, you might even be saving $50 a camera. If you purchase 100 cameras a year, this adds up to a reasonable savings of $5,000. But what happens if your machine, which you sell globally, has a camera that fails. What is the cost of the line going down at your client? How do you look in your client’s eyes? What is the cost for you to fix it?

If you had your choice of buying a camera with the same characteristics at roughly the same price, but one company makes 20,000 a year, and the other makes 200,000 a year, which would you choose? The same is true if you can choose between a company that has offices all over the world, or just in one country. Or one that has many application engineers to answer your questions, or just one.

We just want to point out that if you are making a purchase on price alone, depending upon your circumstances, it might not really be a savings at all. In fact, it might actually not only be costing you money, but it might even be costing you your sleep!

March 22, 2018March 26, 2018

Which Industrial camera would you use in low light?

Our job as imaging specialists is to help our customers make the best decisions on which industrial camera and image sensor works best for their application. This is not a trivial task as there are many data points to consider, and in the end, a good image comparison test helps provide the true answer. In this blog post, we conduct another image sensor comparison for low light applications testing a long time favorite e2V EV76C661 Near Infra Red (NIR) sensor to the new Sony Starvis IMX178 and Sony Pregius IMX174 image sensor using IDS Imaging cameras.

An Industrial camera can be easily selected based on resolution and frame rates, but image sensor performance is more challenging. We can collect data points from the camera EMVA1288 test results and spectral response charts, but one can not conclude on what is best for the application based on one data point. In many cases, several data points need to be reviewed to start making an educated decision.

We started this review comparing 3 image sensors to determine which ones would perform best in low light applications.

Below is a chart comparing the e2v EV76C661 NIR, Sony Starvis IMX178 and , Sony Pregius IMX174 image sensors found in the IDS Imaging UI-3240NIR, UI-3880CP and UI-3060CP cameras using EMVA1288 data to start. This provides us with accurate image sensor data to evaluate.

image sensor comparison — Table 1: Sensor comparison data

Spectral response cufves — Camera Spectral Response curves

We also look at the Quantum Efficiency (QE) curves for the sensors to see the sensor performs over the light spectrum as seen to the left. (As a note, QE is the conversion of photon to an electrical charge (electrons)

For this comparison, our objective is to determine which sensor will perform best in low light applications with broadband light. From table 1, the IMX178 has very low absolute sensitivity (abs sensitivity) with taking ~ 1 photon to help make a adequate charge, however the pixels are small (2.4um), so maybe not gather light as well as larger pixels. It does have the best dark noise characteristics however. In comparison, the e2V sensor has 9.9 photons for abs sensitivity (not as good as 1 photon) and has a larger pixel size (bigger is better to collect light). The IMX174 proves to be interesting as well with the largest pixel of 5.86um and the highest QE @ 533nm.

Using the data from the spectral response curves however, helps give us more insight across the light spectrum. Given we are using a NIR enhanced camera, we will have significant more conversion of light to a create a charge on the sensor across most of the light spectrum. In turn, we expect we’d see brighter images from the e2V NIR IDS UI-3240 NIR camera.

As a note, one more data point is to look at the pixel well depth. Smaller pixels will saturate faster making the image brighter, so if other variables were close, this may also be taken into consideration.

As one can see, this is not trivial, but evaluating many of the data points, can give us some clues, but testing is really what it takes! So, lets now compare the images to see how they look.

The following images were taken with the same exposure, lens + f-stop in the identical low light environment. In the 2nd image, the e2v image sensor in the IDS-UI-3240CP NIR provides the brighter image as some of the data points started to indicate. The IDS UI-3060CP-M (IMX174) is second best.

In low light situations, we can always add camera gain, but we pay the price of adding noise to the image. Depending on the camera image sensor, some have the ability to provide more gain than others. This is another factor to review when considering adding gain. We need to also take into account read noise as this will get amplified with gain. Our next part of our test is to turn up the gain to see how we compare.

The following set of images was taken again with the same lens + f-stop, lighting, but with gain at max for each camera.

The IDS-UI-3060CP-M has the highest gain available, but still keeps the read noise relatively low with 6 electrons. This in low light WITH gain, gives us a nice image in nearly dark environments.

Conclusion
We can review the data points until we are blue in the face and they can be very confusing. We can however take in all the data and help make some more educated decisions on which cameras to test. For example in the first test, we had a good idea the NIR sensor would perform well looking a the QE curves along with other data. In our second test, we may have seen the UI-3060CP had 24X gain vs others still with low read noise, giving an indication, we’d have relatively clean image.

In the end, 1st Vision’s sales engineers will help provide the needed information and help conduct testing for you! We spend a lot of time in our lab in order to provide first hand information to our customers!

1st Vision is the leading provider of industrial imaging components with over 100 years of combined imaging experience. Do not hesitate to contact us to discuss your applications!

Just a few foot notes regarding this blog post:

Magnification of the images differs due to sensor size. Working distance of the cameras was kept identical in all setups and focused accordingly with distance.

This topic can be very complex! If we were to dig in even deeper, we’d take into consideration charge convergence of the pixel which effects sensitivity aside from looking at just QE!.. That’s probably another blog post!

As a reference, this image was taken with an Iphone and set to best represent what my eye viewed during our lab test. Note that the left container with markers was non-distinguishable to the human eye

Clipart courtesy of clipartextra.com

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