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Posts Tagged ‘Fact’

Instagram posts will soon be screened by Facebook fact checkers

08 May

The amount of fake news and conspiracy theories on Facebook and Twitter is troublesome, but by no means limited to those two social media platforms. Instagram users have to deal with a fair share of general misinformation as well.

The company has already been working to reduce the reach of posts containing false information, but is now taking things one step further. Soon potentially misinforming posts will go through parent company Facebook’s fact checking procedures.

Posts that are identified as false will not necessarily be removed but won’t appear on the Explore page or hashtag search. Talking to Poynter, a company spokesperson said: ‘Our approach to misinformation is the same as Facebook’s — when we find misinfo, rather than remove it, we’ll reduce its distribution.’

The newly introduced measures now ensure the fact checkers also find images on Instagram that have not previously been flagged on Facebook.

According to reports Instagram has been working closely with Facebook’s fact checking teams since the US midterm elections. When images with misinformation are identified on Facebook, an image recognition algorithm can search for the same image on Instagram. The newly introduced measures now ensure the fact checkers also find images on Instagram that have not previously been flagged on Facebook.

According to Poynter, Instagram is also considering the option to add pop-ups that alert users who are searching for misinformation. It’s good to see the platform and its parent company Facebook taking a stronger stance against misinformation in social media but for many the measures to counteract fake news and hate messages are still not going far enough.

Articles: Digital Photography Review (dpreview.com)

 
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Sony a9 banding issue: fact or fiction?

30 Jun

Recently, Jared Polin of Fro Knows Photo released a video showing images shot with the Sony a9 and 70-200mm F2.8 GM lens that displayed visible banding across parts of the image in 2% of his shots from a recent soccer match in Philadelphia.* Here’s what the banding looks like at 100%:

This is a 100% crop of the Sony a9 banding issues that Jared Polin noticed in a small portion of his shots of sideline players at a recent soccer match. The bands themselves are 84 pixels in height, each composed of 7 12-pixel bands. Read on to understand why those numbers are significant when it comes to explaining the phenomenon.

Photo: Jared Polin

Blame the electronic shutter?

Not so fast. Some commenters were quick to blame artificial stadium lighting, which can of course interfere with electronic shutters. However, the a9’s electronic shutter is no ordinary electronic shutter: it can scan across the entire sensor in a mere 1/160s (proven by our friend, and well-respected forum member, Jim Kasson here). What does that mean? Meanwhile, the a9’s mechanical shutter isn’t actually much faster – it takes 1/300s to sweep across the image plane.** That means that in typical artificial lighting, which tends to flicker at 60 or 120 Hz, the 1/160s shutter rate of the a9 is fast enough that it’ll only ever really see 1 or 1.3 pulses of the flickering light as the sensor is scanned. The a9’s electronic shutter is only one stop away from catching up to mechanical shutters.

This means that even in the worst artificially-lit scenarios, you might see one large diffuse band across your image at very high shutter speeds (remember: shutter speed determines the intensity of such bands), but generally you’re unlikely to notice if just a quarter of your image happens to have a slight roll-off to a dimmer – or brighter – exposure.

In other words, in the real-world, artifacts caused by the a9’s electronic shutter are rarely an issue under dominant artificial lighting. Furthermore, in this example the match was being played in a mixture of natural and artificial light, with natural light being dominant.

So what caused the banding?

A closer look at the LED advertising boards

Look closely at the image above at 100%, and you’ll see the larger bands themselves are composed of bands 12-pixels high. 12-pixels… rings a bell. Jim Kasson’s work suggested the a9 reads its sensor out in 12-row chunks, possibly by using 12 parallel ADCs (analog-to-digital converters). That’s how it can scan across its entire full-frame sensor so quickly. This suggests the sensor readout is somehow implicated – but how?

Take a close look at the LED advertising boards at 100%:

A shot of the LED advertising boards clearly implicate them as the source of the banding. Each one of those aliased bands are 12 pixels high, and we know from Jim Kasson’s studies that the a9 reads it sensor out in 12-row chunks, using 12 parallel ADCs.

Photo: Jared Polin

The one thing common to Jared’s 2% of images is that the players are at least partially lit by the LED advertising boards on the sidelines. Those panels create an image by rapidly pulsing their red, green, and blue LEDs to allow for different colors and brightness, and it’s the first type of light source we’ve seen that has caused the a9 any grief.

And by rapid switching we do mean rapid. The larger bands are 84 pixels in height, meaning there are about 48 of them across the entire 4000 pixel-high image. Since we know that full sensor readout takes 1/160s, that means those LEDs pulsed 48 cycles in 6.25 milliseconds, or at a frequency of ~7700 Hz.

Even a mechanical focal plane shutter will experience this kind of banding with a light source cycling 7700 times a second. However, the a9’s banding is worse for two reasons:

  1. A mechanical shutter would take half as much time traversing the image plane, which means half as many bands (probably 24 larger bands would show up in these sorts of images).
  2. The a9’s electronic shutter proceeds in 12-row chunks; a mechanical shutter is more analogous to an electronic shutter proceeding line by line, which would yield smoother bands. Not the more hard-edged, lower frequency (and therefore more readily identifiable) 12-row bands that are visually more distracting than if they had been gradual, single-pixel rows transitioning from one color or brightness to another.

This is the reason why Fro only sees banding in some of his photos, and why even in those it is limited to certain surfaces. The bands are most prominent wherever the LED boards were lending the most light to the subject.

Is it a big deal?

So does this matter? Is it as big a deal as some people are making it out to be?

That all depends on how often you expect to run into this situation. These types of LED lights are relatively rare—basically only appearing in scoreboards and ad boards of the kind you see at sporting events. And even when they’re present, the board has to be casting a significant amount of light on your subject for it to cause any problems.

Furthermore, your shutter speed has to be extremely high to make these bands prominent, and even mechanical shutters are likely not entirely immune to some effect from such LED boards.

Even at an image level, the 84-pixel wide bands can be visually distracting if the LED boards are a dominant source of illumination for your (sideline) subject.

Photo: Jared Polin

All those considerations taken together explain why Fro only found banding in about 50 of the 1,905 images he shot.

If you scrolled down here to the bottom to get the definitive answer to the source and cause of the banding, it’s this: very high frequency (>7000Hz) flickering LEDs combined with the 12-row parallel readout that allows the electronic shutter of the a9 to achieve almost mechanical shutter speeds.

Granted, as a camera designed (partly) to satisfy the needs of sports photographers, the a9 is probably going to be found shooting in situations with LED signboards around where, after-hours, they might account for a significant portion of light on your sideline subjects. If that describes the situations you’ll be routinely shooting under, and you’re concerned about the 2% banding rate in sideline action, this may be something to add to your ‘cons’ list when considering this camera.


*Note this is a different sort of banding than the rare striping we investigated in our full review (that results from the masked phase-detection rows of pixels).

**Compare that to the a7R II’s 1/14s, or the Fuji GFX 50S’ 1/4s, electronic or ‘silent’ shutters.

Articles: Digital Photography Review (dpreview.com)

 
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Composition After the Fact: Cropping for Maximum Impact

10 Aug

It may at first seem simple. You took the shot a little wide, or a sneaky branch that you didn’t notice found its way into the edge of your photo. In Lightroom (LR) it’s just a quick press of the R key to activate the crop tool, hold down the shift key to constrain the crop so you don’t get a weird aspect ratio, and your task is complete.

A cropped portrait

The crop tool – simple, yet powerful.

On the contrary, cropping is one of the more powerful tools that you have at your disposal to dial in the composition of your images. Prime lens users will also find that the limited versatility (compared to zoom lenses) can result in the need for cropping more often.

First, let me make the caveat that many aspects of photography are highly subjective. Some of the information and advice offered in this article is my personal opinion, and is the approach I take to create images that fit my style. Personal preference always prevails. Anything called a rule is only so because a common pattern was identified within compositions that are considered especially attractive.

In many respects cropping echoes the fundamental principles of composition. Luckily, if you didn’t get what you wanted the first time around, when you took the photo, you get a second chance, albeit limited, to recompose your images in post-production for maximum impact.

The Basics

The very first thing I look for, and correct, in any photograph that I edit is straight lines. Horizon lines and any vertical lines that are near the edges of the image, should be straight. It absolutely drives me crazy when I see photos with crooked lines.

That being said, lines can be crooked, but it better be obvious that was the intent, otherwise it just looks like careless composition or lazy editing. In the right context a skewed horizon can add drama, and make an image more dynamic.

Photo cropped with crooked horizon.

Crooked horizons can make viewers cringe unless the intent is obvious.

Make this your first step in cropping, because depending on how radically you have to rotate the image you may be forced to crop the edges of the image.

If you have the time when composing the shot, and your camera has a built-in virtual horizon feature for levelling, by all means do so. I have delegated a customizable button on the front of my camera for activating this feature, and I use it all the time.

With the crop tool activated in LR (keyboard shortcut R) there are a few ways to straighten out an image:

  • Drag the Angle slider left or right
  • Click on the value to the right of the slider and drag left or right (scrubby slider)
  • Click on the numerical value and enter whatever you want
  • Hold the CTRL key while dragging along a straight horizontal or vertical line (will correct on either axis) and LR will fix it automatically
  • Also new in LR6 (LR CC) is the “Auto” feature for the crop tool. Just click it and see how it does – then tweak as necessary.

Elimination

A senior photojournalist at a newspaper I once interned for, gave me a memorable piece of advice while critiquing my photos, he said, “crop until it hurts.” It was his way of telling me that I was leaving too much dead or negative space in my compositions.

To this day his advice always resurfaces in my mind when I’m editing images, especially with portraits or other photos with people in them. Fight the urge to become attached to pixels. Crop out half of the photo if need be. Unimportant areas of a photo are not precious real estate.

Cropping to isolate the subject.

You can’t always get as close to the action as you would like (or it is safe to do so) and heavy-handed cropping can make all the difference.

The fact of the matter is that simple is better. We all suffer from attention deficit disorder, and viewers usually don’t want to spend too much precious time analyzing a photo to get the story. Consider the allure of silhouette images. When cropping look for simple compositions and try to distill the scene down to its essence.

Once the image is rotated and you’ve been forced to chop off some of the edges, look for elements that detract, distract or add little to the image. You may not have a choice but to include them, but it’s good practice to be cognizant of them and it may help guide the rest of your editing process or future compositions.

You see many images where the photographer is too conservative when cropping portraits or photos of people. Again, each photo is different, and there is no magic formula, but for example, I find that tight profile shots of people grab my eye more when they are cropped in really close. I am not afraid to cut off the back of the subject’s head, putting their ear in the upper corner of the image, or even cropping the ear out.

Tight cropped portrait

Cropping in very tight can sometimes create a more powerful image.

Negative space can play an important role, especially if shooting for a publication where they need space for text. But, the nice thing about having post-processing options is that you can always revert back to the original. If you compose your images super tight in camera, you can’t get that negative space back.

Leading Lines

Although thoughtfully composing your shots through the viewfinder is one of the more rudimentary skills in photography, there are often distractions. You may find surprises when you pull up the final image on your computer screen.

In photography, as well as painting and other forms of art, you should always be thinking about the arrangement of elements in the image that are going to draw in the viewer’s eye. A compelling subject is just that, but it is your job as photographer to strive to portray that subject in the most powerful, or striking way possible.

Utilizing leading lines to draw in the viewer's eye.

It’s easy to overlook compositional elements while shooting moving subjects. Post -processing cropping reveals additional possibilities for framing your shots like using leading lines to draw in the viewer’s eye.

When we talk about leading lines it’s not always an obvious straight line. Often it is an invisible thread that takes the viewers’ gaze hostage and leads it through the scene. Think of a series of elements that create a pattern.

Diagonal lines which stretch towards the subject are a common, and effective, way to create interest and tension in an image.

Using Crop Overlays as Guidance

In all of its ingenious glory, LR has included several overlays in the Crop tool to help guide your cropping endeavors. There is a basic grid, the Rule of Thirds, the Golden Ratio, the Golden Triangles, diagonals and the Golden Spiral. With the Crop tool active, the keyboard shortcut O cycles through the various overlays and Shift+O rotates the overlay where applicable.

Personally, I find myself using the Rule of Thirds overlay most often. The Rule of Thirds says that when two horizontal and two vertical lines are drawn across the frame to divide it into equal thirds, the subject or elements of interest, should be placed on, or near the intersection of those lines.

Example of the rule of thirds.

The rule of thirds suggests that the subject be placed at the intersection of lines that separate the image into thirds.

An easy mistake to make is placing the horizon line right in the middle of the frame. This is generally considered a no-no, and is a significant compositional faux pas. The Rule of Thirds overlay gives you those handy horizontal lines for recomposing your photo.

The Golden Ratio and Golden Spiral overlays are closely related. There are a bunch of names for this formula including Phi, the Golden Mean and Fibonacci’s ratio. The Golden Ratio grid employs the same basic concept as the Rule of Thirds. I find that the Golden Spiral really isn’t much different, and is more useful to consider in your original composition, instead of trying to apply it after the fact.

The Golden Triangles overlay shows a diagonal line drawn from one corner to another with two branching lines to the other two corners separating the image into four triangles. This gives you a guide for aligning diagonal leading lines, and a suggested location for the subject at the intersection of the lines.

The diagonal overlay calls for placing elements of interest along 45-degree lines drawn across the image. Although the overlay is meant to fine tune this alignment in post-processing, it has been found that artists tend toward this layout intuitively.

The Moral of the Story

Cropping in post-processing is far more than just a simple tool to tighten up composition. Experimenting with various crops of the same image can help you develop an eye for the hidden compositions in a photo.

After you familiarize yourself with the possibilities, you will likely find yourself looking back through your photo library to revisit old images, in order to give them fresh compositions.

Photography is all about seeing, not just looking, and sometimes instead of taking a step back to see the big picture, you need to take a step forward to discover the small one.

What is your thought process when cropping in post-production?

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The post Composition After the Fact: Cropping for Maximum Impact by Jeremie Schatz appeared first on Digital Photography School.


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