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Imatest Customer Profile: Pawel Achtel, ACS

This month, we have a very special customer profile. We had the chance to chat with Pawel Achtel, a cinematographer for the Avatar movies. Check out what he has to say and how he uses Imatest:

Mia

What do you do for work?

Pawel

That’s a tough question because I do a lot for my work. I’m a cinematographer, but also I’m a scientist and inventor. Within cinematography, I not only film images, but I also edit images that I produce. So it’s very difficult to pigeonhole me.

Mia

Is it just you doing everything?

Pawel

Not everything. We’ve got a few teams actually doing different things with the development of cameras. It was just too much for me to do everything and just not possible to do it in such short period of time. It’s definitely a team effort.

Mia

Very cool. How long have you been using Imatest?

Pawel

probably about 20 years. I still have a version that I run on Windows XP virtual machine–so it’s more than since Windows XP.

Mia

Wow, I don’t hear that a lot. You’ve been using it since the beginning, because we’ve been around for about 20 years now.

Pawel

Yes!

Mia

What feature do you find yourself using the most? Perhaps one that you gravitate towards for your work, or one that you found works really well for what you’re doing?

Pawel

So with the work that I do, I’m a little bit obsessed about image sharpness. I’ve been using the MTF and SFR sort of workflow. That’s 90% of what I use Imatest for.

Mia

That one’s definitely good for sharpness. Do you have an example or a use case?

Pawel

There are several use cases, but I do a lot of filming underwater. A limiting factor to image quality is the glass, or the optics. Not many people know that we’re only getting about standard definition quality through just a flat piece of glass simply because of the chromatic aberrations, distortions, astigmatism, and all sorts of other problems associated with it. With the new digital cameras, there’s obviously a big disparity between what glass can produce and what the camera can record. For almost a decade, I’ve been trying to get that optical sharpness up. The only way to do it is to compare it, and in order to compare it, you need to quantify it. I’ve collected a large number of underwater submersible lenses, which are lenses that are designed to produce sharp pictures underwater, but they don’t produce sharp pictures on land. I have inventory of well above 100 lenses. For every lens, I shoot several SFR charts and measure sharpness in the center, mid-frame, edge and corners. This is to be able to cherry pick the lenses.

Pawel

I do a lot of modifications to adapt the lenses for digital sensors, and again, the best way to make those modifications is to be able to test whether you’re actually improving or whether you’re making things worse. All those lenses have MTF charts for many points in a frame, and I can pick up the lens that I think performs best in particular circumstances. So I’ve been using those workflows a lot more recently. I have a test lens that’s extremely sharp–a Sigma 135mm lens. I use that lens as a baseline to compare different digital services and measure the MTF of the actual sensor. That’s only in the center of the frame because the sensor is uniform and the lens performs best in the center of the frame. Those are two main areas that I’ve been using it for.

Mia

Yeah, well, that’s really cool to hear. Cool to hear you are using Sigma lenses too, at least for your baseline test. Those are my favorite.

Pawel

It’s a lens that I actually have. I also have been using a lot of ARRI signature price recently, but they are expensive lenses; they also could be used as a baseline. I just don’t have access to them every day.

Mia

Awesome. How did you get started in imaging science or imaging in general? I know that you said you’re a cinematographer, but you’re also a scientist, engineer, and inventor. What sparked your interest?

Pawel

I’ve been lucky. I had very good general education and I studied, actually, civil engineering, but with a very solid background in physics that allows me to pretty much do anything. With the interest more like a hobby, photographing and filming things sort of turned into a profession that was very much based in science.

Mia

Yeah, I definitely agree. I started out just photography as a hobby, and now here I am. I delved into the scientific aspect of it. It’s really awesome.

Pawel

It’s much easier to turn scientists into very good photographers or cinematographer than teach cinematography with all the math and physics behind it.

Mia

I think especially if you already have that scientific background, it might be easy to translate or throw the artistic aspect into it.

Mia

How did you find Imatest?

Pawel

As I said, I always wanted to improve things. It’s a sort of driver that keeps me going. As I said, if you want to improve something, you need to be able to compare it–you can’t compare it unless you can quantify it. I was on a lookout for ways of analyzing images and at the time there was not much else other than Imatest. Now there are some other packages that claim to do a lot of things that Imatest does, but they’re just not as robust. I think having that history and ability to improve things over time makes it a clearer choice.

Mia

For sure. Maybe I’m biased because I work here and I use it, but yeah, Norman and Henry Koren are so smart and they know so much about image quality. I can understand why it is pretty robust and we’re always looking for ways to improve.

Mia

Are there any other challenges that you faced with image quality testing related to your work?

Pawel

Well, recently with the development of this new camera, we found that we can produce really high resolution images. What I mean by that is we can produce 260 megapixel motion picture, which is 18.7K by 14K resolution. To be able to analyze those quickly and efficiently is certainly a challenge. In the past, I needed to crop to smaller size and analyze bit by bit because it’s quite large.

Mia

Wow, that’s huge!

Mia

That’s all the questions that I have. I know you worked on the new Avatar movie, which is so spectacular.

Pawel

Actually, I had to analyze more than 40 lenses. Every single lens was put on an underwater optical bench with an SFR chart on it. I would shoot several tests and bring them into Imatest to analyze. Those lenses were not just cherry picked for their sharpness, but also for uniformity across the frame. Also, because Avatar was actually shot in 3D underwater, I needed to match those lenses. The two lenses that I actually matched have very similar characteristics, but mirrored because the lenses go on a beam splitter. One lens shoots through a half mirror and one lens bounces off a half mirror, creating two separate images. In order to match those lenses, you’re actually looking for mirrored characteristics in those lenses, but no lens is perfectly symmetrical. I’ve got the lenses in a special box labelled Avatar in case they want to shoot more in the water.

Mia

like I said, it’s really spectacular. I remember seeing the first movie and thinking, “oh, my gosh, this is so beautiful,” and now there’s another coming out. I can imagine it’s going to be very cool.

Pawel

There’s never been a film shot in such way before. The team used, which was my invention, a submersible beam splitter. Prior to this, people were using beam splitters that were housed in underwater enclosure. This is completely different. This beam splitter is completely flooded, and the reason is because it avoids any glass in between. So, there is no limit in resolution. There’s also absolutely no distortions through it, so what you’ll see is images that are completely different. When we first saw those images on set we were like, “Is that underwater? Is that on land?” It just looks unreal. It was underwater, but there’s no distortion. And the peripheral vision is so sharp, crisp, and vivid that is so immersive and just creates this very unique experience.

Mia

I’m very excited to see it, and everybody at Imatest is also excited. We’re happy to be able to work with you and to be able to help with anything. Thank you so much for meeting with me. It’s been a pleasure!

Pawel

Thanks, Mia. Nice talking to you.

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Imatest Customer Profile: Naveen Koul

Mia: The first question is what do you do for work?

Naveen: I’m an image quality engineer. I work mainly on tuning and image quality verification and validation. At present, I’m associated with Nuro.

Mia: How long have you been using Imatest?

Naveen: I have been using Imatest since around 2008.

Mia: Wow, awesome. What feature in the software do you find yourself using the most, or one that you usually gravitate towards?

Naveen: I have mostly used all the features across Imatest. But some features I use are the high dynamic range and noise ones, which are very interesting features Imatest has. Apart from all image quality features, Imatest provides a lot of data in the CSV files and the JSON files, which is quite useful.

Mia: For sure. Do you have any tips for people who are just beginning to use Imatest?

Naveen: Yeah, there’s a lot of very good documentation Imatest provides. Also, I’ve seen a lot of video lectures on YouTube for a beginner to start with and understand the tool well. I will advise, there is a lot of stuff in the CSV and the JSON files which does not get displayed on the images. That is really great data to look at that gives a lot of information about the image quality other than what the output saved images is.

Mia: Yeah, that’s a great bit of information. I make the videos for Imatest that you see on YouTube or on our website, so it’s good to hear they’re helpful. That’s a great idea for a video; showing people how to interpret the JSON files. Thank you so much for doing this!

Naveen: Sure. Thank you.

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Imatest announces new partnership with Edmund Optics

Imatest is proud to announce a new partnership with Edmund Optics.

The partnership will enable customers to seamlessly buy Imatest software and charts via Edmund Optics’ website, and will help both Imatest and Edmund Optics customers develop quality optical systems.

(more…)

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Imatest Customer Profile – Dr. Brian Deegan

Imatest is happy to introduce customer profiles! Each month, we will interview one of our Imatest users to share why they use the software and create a sense of community among our users. Interested in being featured? Reach out to mia@imatest.com.

 

The first customer profile is Dr. Brian Deegan. Based in Ireland, Brian is a long-time user who has utilized the Imatest software across multiple disciplines. Read more about our interview with Brian:

 

Mia: How long have you been using Imatest?

Brian: It must be ten years now at this stage. I started at Valeo in 2011 and have used it throughout my entire career there. I started in university this year and I’m still using it.

Mia: Awesome. And you’re still using it now that you’re at the university?

Brian: Yeah, not as much and not as much directly, but one of the PhD students here is using it as part of this project.

Mia: That’s very cool. Segueing into the next question, what do you do for work?

Brian: I used to work for Valeo vision systems and that’s how Norman [Koren], Henry [Koren], and the team would know me. I was working in automotive image quality, so everything from simple backup cameras to surround view cameras, mirror replacement cameras, cameras for autonomous driving; everything to do with that. In my career I was primarily responsible for, I suppose, image quality, assessment tuning and optimization. So, everything from measuring the sharpness and noise performance of the cameras to trying to get the best image quality for reviewing, machine vision, and performance; that kind of thing.

Mia: What feature in the software do you find yourself using the most or kind of what’s been your favorite feature, if that’s the avenue you want to take it in?

Brian: Yeah, sure. The most common ones that I’ve used would have been the SFR test for measuring the sharpness of the cameras. I’ve used that quite a bit. The step chart tools for measuring color accuracy with the color checker charts as well. I’ve also used the uniformity measurement quite a bit for measuring the color and shading uniformity of lenses. So, those that have been the ones that I’ve used most commonly. There are other ones I’ve used as well for measuring aliasing using the wedge targets, and I use some of the newer ones for the ISO-16505 standard. I do use some of the dynamic range measurements and some of the CPIQ measurements–less often, but I do use those too.

Mia: Well that’s very cool. It seems like you got to cover a lot of the software.

Brian: Yeah. I know that you mentioned features that that I liked: I like the chart order feature. So obviously yours is everywhere, Imatest manufacturers test targets. But every now and again it’s nice to just print off a chart, quick and dirty, for doing quick tests. The chart order function has proved very useful over the years. Another one that’s nice—it’s basically an image quality simulator where you can simulate different MTF curves for illustration and demonstration purposes.

Mia: Cool, thank you. Being that you’re in the image quality industry directly, is there any direction you’d kind of like to see Imatest go?

Brian: Not particularly as such. In terms of image quality assessment, there’s only a handful of companies that are involved, and Imatest is one of the leaders in the area. I’ve given feedback over the years as time has gone by. But you know, a team like Norman and Henry, and even Paul Romanczyk, they go to the standards meetings and are heavily involved. Whatever is going on in the industry, Imatest has had people that are either at the conferences or involved with the standards. So I think in terms of the developments that are going on in the industry, it’s safe to say Imatest has a reasonable, good finger on the pulse from that point of view. In terms of features and stuff like that, I suppose a couple of years ago I would have said that Imatest weren’t as good as some of the competitors in terms of some of the hardware, Imatest was more refined for targets and software. However, that gap has closed in the last few years.

 

Thank you to Brian for his valuable feedback and participation!

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Using images of noise to estimate image processing behavior for image quality evaluation

In the 2021 Electronic Imaging conference (held virtually) we presented a paper that introduced the concept of the noise image, based on the understanding that since noise varies over the image surface, noise itself forms an image, and hence can be measured anywhere, not just in flat patches.

You can download the full paper (in the original PDF format) here.

(more…)

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Imatest macOS package installer “can’t be opened because Apple cannot check …”

To resolve this issue in macOS, open System Preferences:Security&Privacy and in the General tab give permission to open the installer.

 

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Imatest Announces the WFOV Module

Imatest introduces its new Wide Field of View (WFOV) Module, which is an easy-to-use platform for testing sharpness in cameras with FOV up to 200º. This solution integrates with the Modular Test Stand and features three rail systems for easy positioning and mounting of camera devices, peripheral test targets, and Kino Flo LED panels. The main chart holder accommodates a variety of different test charts; mounting points for Isolight Pucks enable easy measurement of lighting brightness and color uniformity. (more…)

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Imatest EI Presentations Now Online

The research papers presented at this year’s Electronic Imaging Symposium (EI 2020) by Imatest engineers are now available. (more…)

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Seoul, South Korea – Imatest Training Course – October 20-21, 2020

Imatest in Seoul

Imatest engineers will visit Seoul, October 20-21, 2020, to offer a paid two-day training course (October 20-21) to professionals using or considering Imatest software to improve their image quality testing processes. A free information seminar will be offered on October 19. 

Seoul 2020 training image

Two-Day Training Course

image (2)

The training course offers attendees insight into the capabilities of Imatest software in both research and development and manufacturing environments.

After taking this course, you will have:

  • An understanding of key image quality factors
  • Practical knowledge of how to apply Imatest software to measure the factors
  • An overview of how to set up and tailor your test lab for accurate measurements

It is highly recommended you have a basic understanding of how cameras work (see recommended prerequisites). A detailed training schedule is also available.

Date and Time

October 20-21, 2020
09:00 – 18:00, depending on the questions.

Location Details

TBD

Instructor

TBD

Sign up online or contact a reseller in your area.

Register for Training

Free Information Seminar

If you are interested in finding out more about how Imatest software can improve your image quality testing, we encourage you to come to our free information seminar.

Time

October 19, 2020
Time TBD

Location

TBD

Please register if you are interested in attending. We look forward to meeting you in person.

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Imatest Announces Modular Test Stand

Boulder, Colorado, August 30, 2019—Imatest, a global provider of image quality testing solutions, now offers a Modular Test Stand (MTS) that enables you to produce superior cameras while significantly reducing time spent in the lab. (more…)

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July 2019 Newsletter

Our newsletter features our products, company news, educational image quality articles, Imatest events, and relevant industry articles. Subscribe to receive our newsletters in your inbox. (more…)

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June 2019 Newsletter

Our newsletter features our products, company news, educational image quality articles, Imatest events, and relevant industry articles. Subscribe to receive our newsletters in your inbox.

Imatest-Furonteer Partner to Reduce Geometric Camera Calibration Time

Imatest and Furonteer Reduce Camera Instrinsic Calibration Time

Imatest and Furonteer partnered in early 2019 to provide high throughput production machines for geometric calibration of single and multicamera devices.

 

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Imatest software testing program for early access - Pilot Program

Join our Pilot Program

A new Imatest software release is coming soon. Join our pilot program for early access to the new version in testing.

 

Join Now

(more…)

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Shanghai, China – Imatest Training Course – November 11-12, 2020

Imatest in Shanghai

Imatest engineers will visit Shanghai, China, November 11-12, 2020, to offer a paid two-day training course to professionals using or considering Imatest software to improve their image quality testing processes. A free information seminar will be offered on November 10.

Shanghai 2020 training image

Two-Day Training Course

image (2)

The training course offers attendees insight into the capabilities of Imatest software in both research and development and manufacturing environments.

After taking this course, you will have:

  • An understanding of key image quality factors
  • Practical knowledge of how to apply Imatest software to measure the factors
  • An overview of how to set up and tailor your test lab for accurate measurements

It is highly recommended you have a basic understanding of how cameras work (see recommended prerequisites). A detailed training schedule is also available.

Date and Time: November 11-12, 2020; 09:00 – 18:00, depending on the questions.

Location Details: TBD

Instructor: Henry Koren, Director of Engineering, Imatest

Registration: Contact a reseller in your area or cick the registration button below.

Register for Two-Day Training

Free Information Seminar

If you are interested in finding out more about how Imatest software can improve your image quality testing, we encourage you to come to our free information seminar.

Date and Time: November 10, 2020; time: TBD

Location: TBD

Register for Free Information Seminar

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Seoul, South Korea – Imatest Training Course – October 20-21, 2020

Imatest in Seoul

Imatest engineers will visit Seoul, October 20-21, 2020, to offer a paid two-day training course (October 20-21) to professionals using or considering Imatest software to improve their image quality testing processes. A free information seminar will be offered on October 19. 

Seoul 2020 training image

Two-Day Training Course

image (2)

The training course offers attendees insight into the capabilities of Imatest software in both research and development and manufacturing environments.

After taking this course, you will have:

  • An understanding of key image quality factors
  • Practical knowledge of how to apply Imatest software to measure the factors
  • An overview of how to set up and tailor your test lab for accurate measurements.

It is highly recommended you have a basic understanding of how cameras work (see recommended prerequisites). A detailed training schedule is also available.

Date and Time: October 20-21, 2020; 09:00 – 18:00, depending on the questions.

Location Details: TBD

Instructor: Henry Koren, Director of Engineering, Imatest

Registration: Contact a reseller in your area to register for this two-day course or click the registration button below.

Register for Two-Day Training

Free Information Seminar

If you are interested in finding out more about how Imatest software can improve your image quality testing, we encourage you to come to our free information seminar.

Date and Time: October 19, 2020; Time is TBD

Location: TBD

Register for Information Seminar

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San Jose, CA – Imatest Training Course – August 6-7, 2020

Imatest in San Jose

Imatest engineers will visit San Jose, California between August 6-7, 2020 to host a paid two-day training course to professionals using or considering Imatest software to improve their image quality testing processes.

Image Quality Testing Training with Imatest on August 6-7, 2020

Two-Day Training Course

image (2)

The training course offers attendees insight into the capabilities of Imatest software in both research and development and manufacturing environments.

After taking this course, you will have:

  • An understanding of key image quality factors
  • Practical knowledge of how to apply Imatest software to measure the factors
  • An overview of how to set up and tailor your test lab for accurate measurements.

It is highly recommended you have a basic understanding of how cameras work (see recommended prerequisites). A detailed training schedule is also available.

Date and Time: August 6-7, 2020; 09:00 – 18:00 (depending on questions)

Location Details: TBD

Instructor: TBD

Register for Two-Day Training

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Germany – Imatest Training Course – March 24-25, 2020

Imatest engineers planned to visit Germany on March 24-25, 2020 to host a paid two-day training course to professionals using or considering Imatest software to improve their image quality testing processes.

In light of the COVID-19 Coronavirus, this training course will be held remotely.

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Correcting nonuniformity in slanted-edge MTF measurements

Slanted-edge regions can often have non-uniformity across them. This could be caused by uneven illumination, lens falloff, and photoresponse nonuniformity (PRNU) of the sensor. 

Uncorrected nonuniformity in a slanted-edge region of interest can lead to an irregularity in MTF at low spatial frequencies. This disrupts the low-frequency reference which used to normalize the MTF curve. If the direction of the nonuniformity goes against the slanted edge transition from light to dark, MTF increases. If the nonuniformity goes in the same direction as the transition from light to dark, MTF decreases. 

To demonstrate this effect, we start with a simulated uniform slanted edge with some blur applied.

Then we apply a simulated nonuniformity to the edge at different angles relative to the edge. This is modeled to match a severe case of nonuniformity reported by one of our customers:

 

Here is the MTF obtained from the nonuniform slanted edges:

If the nonuniformity includes an angular component that is parallel to the edge, this adds a sawtooth pattern to the spatial domain, which manifests as high-frequency spikes in the frequency domain. This is caused by the binning algorithm which projects brighter or darker parts of the ROI into alternating bins.

 

Compensating for the effects of nonuniformity

Although every effort should be made to achieve even illumination, it’s not always possible (for example, in medical endoscopes and wide-FoV lenses).

Imatest 4.5+ has an option for dealing with this problem for all slanted-edge modules (SFR and Rescharts/fixed modules SFRplus, eSFR ISO, SFRreg, and Checkerboard). It is applied by checking the “Nonuniformity MTF correction” checkbox in the settings (or “More” settings) window, shown on the right.

When this box is checked, a portion of the spatial curve on the light side of the transition (displayed on the right in Imatest) is used to estimate the nonuniformity. The light side is chosen because it has a much better Signal-to-Noise Ratio than the dark side. In the above image, this would be the portion of the the edge profile more than about 6 pixels from the center. Imatest finds the first-order fit to the curve in this region, limits the fit so it doesn’t drop below zero, then divides the average edge by the first-order fit. 

The applied compensation flattens the response across the edge function and significantly improves the stability of the MTF:

Summary

For this example, Imatest’s nonuniformity correction reduces our example’s -26.0% to +22.8% change in MTF down to a -3.5% to +4.7% change. This is an 83% reduction in the effect of the worst cases of nonuniformity.

MTF50 versus nonuniformity angle without [blue] and with [orange] nonuniformity correction

While this is a large improvement, the residual effects of nonuniformity remain undesirable. Because of this, we recommend turning on your ISP’s nonuniformity correction before performing edge-SFR tests or averaging the MTF obtained from nearby slanted edges with opposite transition directions relative to the nonuniformity to reduce the effects of nonuniformity on your MTF measurements further.

Detailed algorithm

We assume that the illumination of the chart in the Region of Interest (ROI) approximates a first-order function, L(d) = k1 + k2d, where d is the horizontal or vertical distance nearly perpendicular to the (slanted) edge. The procedure consists of estimating k1 and k2, then dividing the linearized average edge by L(d). 

k1 and k2, are estimated using the light side of the transition starting at a sufficient distance dN from the transition center xcenter, so the transition itself does not have much effect on the k1 and k2 estimate. To find dN we first find the 20% width d20 of the line spread function (LSF; the derivative of the edge), i.e., the distance between the points where the LSF falls to 20% of its maximum value. 

dN = xcenter + 2 d20 

If the edge response for x > dN has a sufficient number of points, it is used to calculate k1 and k2 using standard polynomial fitting techniques. The result is a more accurate representation of the edge with the effects of nonuniformity reduced.

Future work

  • Consider the 2D nonuniformity across the ROI before sampling the 1D average edge
  • Use an image of a flat-field to perform nonuniformity correction within Imatest
  • Consider the impact of noise which was not included in this study
  • Incorporate enhancements to the slanted-edge algorithms into future revisions of ISO 12233

 

For any questions on how to do this, or how we can help you with your projects, contact us at support@imatest.com.

 

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Greetings From the Path of Totality

If you were lucky enough to travel to the path of totality on Monday, August 21st, you know firsthand how incredible it is to suddenly experience twilight in the middle of the day. The sun transforms into a hole in the sky, casting eerie shades of purple and a 360º sunset on the clouds. Just minutes later, the sun rises over the moon, creating a diamond ring effect. Witnessing this astronomical spectacle in person can’t compare to the photos and descriptions, but the images that I captured in Kearney, Nebraska are truly remarkable! Fewer than 1 in 1,000 people ever have the chance to see the Sun’s atmosphere in their lifetime, and I am extremely grateful to be one of them!

My camera setup. Panasonic GH3 with Canon adapter and 55-250mm Canon lens. I made my own solar filter with film purchased from Spectrum Telescope. I forgot my tripod, so I had to use my gorilla pod.

Composite image from my time-lapse! Each snapshot is about 3 minutes apart.

Composite image of totality! The solar filter was removed during totality and then reapplied for the final phase.

“God’s diamond ring”

The solar corona, consisting of 2-million-degree plasma.

Timelapse 

Each frame was taken 3 seconds apart and play back is 24 frames per second. The solar filter was removed during totality and then reapplied for the final phase.

– Alex Schwartz, Video Production & Mechanical Engineering Intern

 

 

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Imatest Support for CPIQ Metrics

What is CPIQ?

IEEE-SA working group P1858 created the CPIQ standard. CPIQ seeks to standardize image quality test metrics and methodologies across the mobile device industry, correlate objective test results with human perception, and combine this data into a meaningful consumer rating system.
(more…)

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