What is hdr photography, why is it good and how to get it? How to take a beautiful HDR picture on a smartphone.

HDR stands for High Dynamic Range, for a more concise and convenient use, the English abbreviation is used, HDRI stands for High Dynamic Range Image. HDR is a type of photography that allows you to create images with more dynamic range than is normally possible.

To understand what it is and how to use it, you first need to understand what dynamic range is.

Dynamic Range

Dynamic range is a measure of the spectrum of illumination across various levels- from the darkest blacks to the brightest whites - which can be displayed on the camera. Dynamic range determines the amount of contrast that you can capture or display without losing detail.

The dynamic range that you can capture with a camera is much higher than what can be displayed on your monitor.

Why is it so important?

Some scenes may be too contrasty due to certain types of lighting. That is why experts advise avoiding shooting at noon in bright sunlight, as the cameras cannot cope with the full range of light. In low light, other problems may arise - the image will be too dim, with no contrast. As a result, the photo will have soft shadows, but the frame itself will be a little nondescript.

Image at midtones

Are there ways to avoid this?

With digital shooting, these problems are much easier to solve, since the result of the shooting is visible on the display instantly. Depending on the resulting frame, you can change the camera settings, or change the angle. We can also use a flash to reduce the contrast on a sunny day and use a special filter to balance out the difference in brightness between the sky and the landscape.

Moreover, there are processing techniques that can be used in Photoshop, especially if the shooting took place in RAW mode, which allows you to get pictures with maximum detail in the darkest and brightest areas of the frame.

How does HDR work?

HDR allows you to use a larger range of brightness in an image, and the range can be much larger than in a normal image. True Image HDR is created from multiple shots of the same scene, taken at slightly different exposures.

Each exposure captures a portion of the tonal range. Then they are combined into one image using special software.

What is meant?

True Image HDR contains a much larger range of tones - too much, in fact, to be displayed on a normal computer monitor or printed on paper.

They are typically stored as 32-bit files, which can transfer up to 4,300,000 shades of each color channel. In comparison, a standard JPEG file can transmit 256 (8-bit) shades per channel, and a RAW file transfers from 4000 (12-bit) to 16000 (16-bit) shades per channel.

So, what to do with this very large file?

The next step for most HDR images is tone mapping. In doing so, the program uses a 32-bit HDR image to create an image with a contrast range that can be displayed when printed or displayed on a monitor.

Each tonal value will be recalculated at a different scale. The result is a new image in which you can see all the details in both the bright highlights and the darkest areas of the shadows. That's the whole point of the tone mapping you can get from HDR.

How to creatively use HDR?

Many enthusiasts are not only using HDR in combination with software, they have gone further. They set themselves the task of not creating a realistic image, they strive to create an original artistic image which no longer looks realistic. The resulting effect is similar to that used in the hyper-realistic style in painting. Some people like it, and some don't.

Image at brightest exposure

What software is needed?

There are many programs that include HDR - including free ones. Most famous program is Photomatix Pro, but the latest version of Photoshop (CS5) has a built-in HDR center.

Usually in HDR programs There is whole line sliders to help you control the tone and give you the ability to make the effect just the way you like it.

How to shoot with HDR?

Essentially, the process is the same as for bracketing. The number of shots you need depends largely on the actual tonal range of the scene you are shooting. The greater the contrast, the more frames you should take.

Usually three photos are taken, but depending on the shooting situation, you may need to take as many as nine shots, each one or two stops different from the previous one. Some DSLRs have AEB (Auto Exposure Bracketing) which will allow you to do this without any additional hassle.

Image at darkest exposure

What other settings should I use?

The sequence in your frames should be as close in content to each other as possible (although obviously the brightness will vary). Any changes caused by motion can create a halo that your software then has to deal with.

Camera improvements and HDR support are one of the promised changes in iOS 4.1. HDR mode (High Dynamic Range in English - high dynamic range) is an increase in the dynamic range of a picture taken with a digital camera.

What is HDR mode

Let's imagine the following situation. Early morning or evening in a room with natural light. You perfectly see all the details of the room and the surrounding landscape outside the window. But when you try to take a photo, you get either a detailed interior and a window that is too bright, or a dark room and a fairly well-designed street landscape. The new camera mode will avoid this and get the result that corresponds to reality.

Now your iPhone will take three frames at a time and combine the images in the final shot. Using the mode makes it possible to balance the tonality of surrounding objects, as a result of which the image more fully reflects the real picture and it just looks better. Let's try to figure out in which cases the application of the effect allows you to get a better picture.

When can I use the HDR graphic effect

Always use this mode in the following cases:

• in landscape photography (helps to smooth out the contrast between the bright bright sky and the dark earth);
• in portrait shooting in bright daylight or strong artificial lighting (removes the effect of a whitened face);
• when the lighting is not enough (dark room and light from the window).
• When not to use the mode:
• when shooting moving objects (considering that the final image is made up of three intermediate ones, the image may turn out to be blurry);
• if you want a high-contrast shot (many images look better with strong detail contrast, and using the mode smoothes it out a lot);
• if you want to take a rich and bright photo (using the mode makes the image paler).

To turn on HDR on iPhone, simply tap on the corresponding icon located at the top of the screen in Capture mode. Now you can take a picture as usual. The phone will take a little longer to process and save the image.

Practice shows that the graphic effect is especially useful when shooting landscapes. A conventional camera often spoils the sky, making it white and not conveying a rich blue tint at all. The mode allows you to avoid this and make a very high-quality frame.

Finally, it should be noted that any artificial modes and filters must be used with caution. If you want to be sure that the resulting image will not be corrupted, reframe without applying HDR. In the future, the resulting image can be edited using special program. In addition, after a while, this approach will show whether you need to use artificial modes or not.

Until recently, the cell phone cameras of the Pixel and Nexus line were nothing special, but Google developers have implemented a new HDR + photo post-processing mechanism, thanks to which they have risen to the first positions in various ratings. And if you're curious about how HDR+ works and how to enable it on your smartphone, read on.

What is conventional HDR

To understand how HDR+ works, let's start with regular HDR.

Insufficient coverage of the dynamic range due to the small size of the matrix - main disadvantage all smartphone cameras. To solve this problem, we developed the HDR (High-Dynamic Range) algorithm, the principle of which is to overlay and merge three images: a frame with a standard exposure level for a given scene, an underexposed frame, where only overexposed areas of the original image and overexposed are clearly visible. frame in which only the dark areas of the original image are visible. The result is a picture with a good study of all the details. This method can be called a small revolution in smartphone photography.

The disadvantages of the HDR algorithm include: for a long time shooting, splitting objects moving in the frame, as well as blurring the entire picture even with minimal movement or camera shake.

What is HDR+

HDR+ (High-Dynamic Range + Low Noise) is an algorithm that has a number of outstanding features without the disadvantages of HDR. Unlike HDR, the new HDR + algorithm is almost not afraid of smartphone shaking and movement in the frame. In addition, this algorithm is able to improve the quality of color reproduction, which is extremely important in low light and at the edges of the frame, along with this, it greatly expands the dynamic range of the photo. And finally, the HDR + algorithm is able to eliminate noise with almost no loss of detail.

The first smartphone to support HDR+ in 2013 was the Nexus 5. The Android 4.4.2 update brought support for HDR+ mode, which radically changed the quality of night shots. The brightness over the entire field of the frame has not changed much, of course, but when saving small parts the noise has almost disappeared. And of course, the excellent color rendering, which sharply distinguished the pictures of the Nexus 5 from the pictures of other smartphones of that time, could not but please.

History of HDR+

The history of creating an algorithm that works wonders using conventional Nexus and Pixel cameras began in 2011, when the head of Google X, Sebastian Thrun, decided to look for a camera for Google Glass augmented reality glasses. He made very strict requirements for weight and dimensions. The size of the camera matrix had to be made even smaller than in a smartphone, which would lead to a large amount of noise in the picture. Therefore, it was decided to try to improve the quality of the photo using algorithms. That's what Stanford University computer science professor and computational photography expert Marc Levoy has been working on in software-based image capture and processing technology.

The Gcam team, led by M. Leva, began to study the method of combining several images into one frame (Image Fusion). The quality of photos processed using this method has improved markedly. They became brighter and clearer, and the amount of noise was noticeably reduced.

This technology debuted in 2013 in Google Glass. Then, renamed HDR +, it appeared in the Nexus 5 in the same year.

How HDR+ works

HDR+ technology is extremely complex. Therefore, we will not analyze it in detail within the framework of this article, but main principle consider work.

How HDR+ works

To preserve the maximum amount of detail in the final photo After pressing the shutter button, the camera captures a whole series of frames with a fast shutter speed, i.e. underexposed pictures. The number of frames depends on the light level and the amount of detail in the shadows. Then the entire series of images is combined into one.

Due to the slow shutter speed, each photo in the series is relatively clear. For the base, the best of the first three frames is used for both sharpness and detail. After that, the system divides all received frames from this series into fragments and checks adjacent fragments for compatibility. If extra objects are found in one of the fragments, the algorithm removes this fragment and selects a similar one from another frame. Next, the images are processed using a special algorithm to reduce image blur, which is mainly used in astrophotography.

So, using a fast shutter speed saves our photos from overexposed areas, expanding the dynamic range of the image. It remains only to remove the noise in the dark areas with a special algorithm.

After that, the photo is processed by the noise reduction system. The system includes a pixel color averaging method based on multiple images and a noise prediction system. At the boundaries of tone transitions and texture changes, the goal of “noise reduction” is to minimize the loss of detail even at the cost of having a little noise, but in areas with a uniform texture, the algorithm aligns the image to an almost perfectly uniform tone and with excellent preservation of transitions of all shades.

Finally, the resulting image is post-processed. The algorithm minimizes the partial the resulting dimming light entering at an oblique angle (vignetting). Replaces pixels in high-contrast edges with adjacent ones (chromatic aberration). Makes shades of green more saturated, shifts blue and purple shades towards blue. It also enhances sharpness (sharping) and performs other operations that significantly improve the quality of the final photo.

HDR+ pipeline algorithm in action.

A photo taken with a Samsung stock camera in HDR is on the left, and on the right is a photo taken with a Gcam in HDR+. When comparing these two photographs, it is striking that due to the loss of detail in the sky, objects on the ground are better drawn.

Google Pixel HDR+ update difference

ZSL (Zero Shutting Lag) technology was invented in order to take snapshots. The smartphone immediately after starting the camera shoots from 15 to 30 frames per second, depending on the degree of illumination. Pixel decided to use this technology to work HDR + in its own way. When you press the shutter button, the smartphone selects from 2 to 10 frames from the ZSL buffer. Then the best one is selected from the first two or three frames, and the rest, as in the previous version of the algorithm, are superimposed in layers on the main one.

Along with this, a division into two modes appeared: HDR + Auto and HDR +. The latter takes as many shots as possible to create the final photo. It turns out more juicy and bright.

HDR+ Auto captures fewer photos, making moving subjects less blurry, less hand-shake, and a photo almost instantly when you press the capture button.

In the version of Google Camera for the Pixel 2/2XL, HDR+ Auto has been renamed to HDR+ On, and HDR+ has been renamed HDR+ Enhanced.

The second generation of the Google Pixel introduced a special co-processor called the Pixel Visual Core. Currently, the chip is only used for accelerated processing of HDR + photos, and also provides third-party applications with the ability to capture HDR + photos. The quality of photos taken by Google Camera, its presence or absence does not affect in any way.

Google uses HDR+ even to fix hardware issues. Due to a design error, the Google Pixel/Pixel XL may have taken a photo with strong backlight. Google has released an update that uses HDR+ to remove this backlight by combining shots.

Advantages and disadvantages of HDR

Let's highlight the main advantages of HDR +:

• The algorithm remarkably removes noise from photographs, practically without distorting the details.
• Colors in dark plots much richer than with single-frame shooting.
• Moving subjects are less likely to see double in shots than when shooting in HDR mode.
• Even when taking a picture in low light conditions, the chance of blurring the picture due to camera shake is minimized.
• The dynamic range is wider than without HDR+.
• Color rendition is mostly more natural than with single-frame shooting (not for all smartphones), especially at the corners of the picture.

In the illustrations below, on the left is a photo from the stock camera of the Galaxy S7, and on the right side is a photo in HDR + through Google Camera on the same device.

Night photos of the city. Here you can clearly see that HDR + gives us the opportunity to get a clear image of a group of citizens located under the Beeline sign. The sky looks clear, the road sign is clear. The grass, as it should be, is green. Beeline sign with correct color rendering. Clear drawing of balconies, wires and tree crowns. Important - detail on the trees on the right (in the shadows) in HDR + is somewhat worse than in the stock camera.

HDR + has few drawbacks, and they are insignificant for most scenes. Firstly, creating an HDR+ photo requires a lot of CPU and RAM resources, which leads to a number of negative consequences:

• battery consumption increases and the device heats up when combining a series of shots;
• You can't take multiple shots quickly.
• instant preview is not available; the photo will appear in the gallery after processing is complete, which on the Snapdragon 810 lasts from up to four seconds.

Some of these issues have already been addressed with Pixel Visual Core. But this coprocessor will most likely remain the trump card of the Google Pixel.

Secondly, the algorithm needs at least two photos to work, and on average, four to five frames are captured. That's why:

• there will definitely be situations in which the algorithms will fail;
• HDR+ loses a bit to classic HDR in terms of dynamic range coverage;
• taking a single photo and processing it using a fast ISP co-processor will be preferable in action scenes, because it allows you to avoid ghosting and blurring of objects at low shutter speeds.

What devices does HDR+ work on?

In theory, HDR+ can work on any smartphone with Android 5.0 or higher (requires Camera2 API). But for marketing reasons, as well as due to the presence of some optimizations that require special hardware components (the Hexagon co-processor in Snapdragon), Google intentionally blocked the inclusion of HDR + on any device other than Pixel. However, Android wouldn't be Android if enthusiasts didn't find a way around this limitation.

In August 2017, one of the w3bsit3-dns.com users managed to modify google app Camera so that HDR+ can be used on any smartphone with a Hexagon 680+ (Snapdragon 820+) signal processor and Camera2 API enabled. At first, the mod did not support ZSL, and in general it looked damp. But even this was enough to improve the quality of photography smartphones Xiaomi Mi5S, OnePlus 3 and others to a level previously unattainable for them, and HTC U11 got the opportunity to compete on equal terms with Google Pixel.

Later, other developers joined the adaptation of Google Camera on phones of third-party vendors. After some time, HDR + even started working on devices with Snapdragon 808 and 810. Today, for almost every smartphone based on Snapdragon ARMv8, running Android 7+ (Android 6 in some cases) and able to use the Camera2 API, there is a ported version Google camera. Often it is supported by a single enthusiast, but usually there are several such developers at once.

In early January 2018, XDA user miniuser123 managed to run Google Camera with HDR+ on his Exynos-powered Galaxy S7. A little later it turned out that Google Camera also worked on the Galaxy S8 and Note 8. The first versions for Exynos were unstable, often crashed and hung, optical image stabilization and ZSL did not work in them. Version 3.3 is already fairly stable, supporting optical image stabilization and ZSL and all Google Camera features except for portrait mode. And supported devices now include several Samsung A-series smartphones.

How to enable HDR+ on your phone

If you have an Exynos smartphone, then the choice is small. Go to the XDA discussion thread, open the V8.3b Base spoiler (if you have Android or Pixe2Mod Base (for Android 7) and download the latest version. You can also visit the Telegram group, where all Google Camera updates are posted promptly.

Owners of smartphones with the Qualcomm process will have to look. Enthusiasts actively support HDR+ versions of Google Camera for a variety of smartphones. I recommend to google and walk around the topics of discussion of the camera and the device itself in forums such as XDA. At the very least, there will be users trying to run HDR+.

To all of the above, I will mention that there is a page on the Internet where almost all versions of Google Camera are collected, on which it is convenient to test various Gcams on little-known devices.

Conclusion

The HDR+ algorithm serves as a vivid demonstration of the possibilities of mobile digital photography. Perhaps today it is the most efficient image processing algorithm available. HDR + is enough for one photomodule to create a picture, bypassing the double photomodules of some gadgets in terms of quality.

When choosing and buying a new smartphone, most of us pay attention to the device's camera and its capabilities. And there is nothing surprising in this. Because today mobile phone is not just a means of communication, but a useful and multifunctional gadget that can replace both a camera and a video camera. At the same time, it is believed that truly high-quality pictures can only be obtained on a smartphone that supports HDR shooting mode. Is it so? And what is this option anyway? We will talk about this and much more below.

As you probably guessed, HDR is shorthand. In general, this technology is called High Dynamic Range. Literally translated, it sounds like “high dynamic range”. What is the point of this option? Now let's explain. HDR mode is a special method of taking photos, in which the camera takes several frames in turn at different shutter speeds and exposures in order to subsequently combine them into one image.

Moreover, it concentrates on areas with different indicators of brightness, contrast and distance from the lens. Then all frames are processed by the built-in program. They are superimposed on each other, and the system analyzes their quality, choosing the clearest fragments from the entire series. As a result, as from several puzzles, one single shot is obtained, which took the best from each frame.

How many smartphones support HDR shooting? I guess, yes. There is this option on devices from brands such as xiaomi, meizu, lg, samsung and more. others

On iPhones, you can also use this wonderful feature. And Apple has been equipping its devices with this technology for a long time, starting with the iPhone 4. All subsequent models (iPhone 5, 5s, 6, 6s, SE, 7 and 8) also have a camera with the ability to create HDR images.

Advantages of this option

What does the HDR function ultimately give (by the way, many users do not pronounce “ash di er”, but “hdr”)?

1. Pictures are of better quality.
2. Increased detail and clarity.
3. Dark areas are minimized and, conversely, overly bright areas.
4. Increases the range of brightness and color depth.

As you can see, there are many benefits to shooting in HDR mode. True, it takes much more time to create several shots and their subsequent processing than with a photo without HDR. In many ways, this mode is useful only when shooting static objects or landscapes. If you shoot moving elements with HDR, then it is likely that they will simply be blurred or duplicated.

For reference! The camera in the Google Pixel smartphone is called one of the best. The pictures obtained with it, by many criteria, turn out to be even better than the photos from the iPhone 7 and Samsung Galaxy S7. In many ways, this is the merit of the HDR + mode. It was this option in the camera of an android smartphone that made it possible to achieve such high results in the confrontation with serious and eminent competitors.

Are there any downsides to HDR mode?

As you can see, this option is really useful. But HDR still has its downsides. So let's talk about the "fly in the ointment":

1. In some cases, the photos look somewhat unnatural. Especially when shooting scenes with solid objects.
2. HDR mode in the smartphone camera does not allow you to take bright pictures. The fact is that when creating a series of frames with different shutter speeds and focus, the system averages the brightness values.
3. The shooting process itself is slower. In HDR mode, even the fastest and most modern camera takes a little more time than when taking a regular picture. After all, you have to make a series of 5-10 frames, and then mount them into one more. All this takes a couple of seconds. In addition, the processor of the smartphone is additionally loaded.

How to enable HDR mode and when should you use this option?

To activate this mode, no third-party applications need to be installed. Everything is done in the "Chamber" itself. For example, on the iPhone, in the photo window itself, there is an “HDR” icon at the top (however, it is not on the iPhone 8 and iPhone 8 Plus). Just click on it and select "HDR on." or "HDR auto" to activate this feature. Then point the camera and press the round key.

Nothing complicated, right? Just keep in mind a couple of nuances:

1. In HDR auto mode (first introduced in iOS 7.1 on the iPhone 5s), the iPhone determines for each shot which option came out better: with or without HDR. The system will automatically select the optimal result, and delete the other photo.
2. In "HDR on" mode Apple smartphone creates an HDR version for every shot. That is, the user can compare two options and choose the one he likes the most. But that's just the disk space in this case, it is hardly possible to save.

When is the best time to enable HDR? It is best to activate the mode if the smartphone camera does not cope with the task. Let's say you're shooting against the sun or in the shade of a building. Here, of course, it is worth using HDR. Don't expect miracles though. If the lighting is very poor, then the HDR mode will not help to get high-quality images.

You should also turn on HDR in your smartphone camera in such cases:

1. Portrait photography.
2. Landscape photography.
3. When working with small objects. For example, you need to take a photo of several pages of a catalog or magazine.
4. In street photography of static objects. Whether it's a monument, a house, or a car parked at the side of the road.

When is the best time to skip HDR?

As for when it is strongly not recommended to use this function:

1. If you or other objects are moving. Since when shooting in HDR mode, in this case it will turn out blurry photo(after all, as you know, a series of frames is taken to create one picture).
2. If you are shooting contrasting scenes. Using HDR will "smooth out" the difference between light and dark areas. But this alone will not improve the image quality.
3. If there is a scene with bright colors in front of your camera lens. The fact is that HDR can make the picture even more saturated in brightness and color scheme. As a result, the photo will become unrealistic.

In all of the above options, a camera with HDR enabled will definitely not produce a good, traced and harmonious in brightness photo. It is better to dig into the settings in the normal shooting mode.

By the way, what about those users whose smartphones do not have a camera with HDR? We will not advise you to purchase a new device. Let's just say that in the digital store you can find a number of applications that will kind of give your photos the effect that you shot them in High Dynamic Range.

For reference! It is noteworthy that the owners of budget smartphones use the HDR mode much more often than those who use the flagship and top models. This is explained by the fact that expensive devices are equipped with a better camera, which has an extended dynamic range.