Hi All, this is Aswin from TechieDrone with another topic that I feel everyone(atleast those interested in photography) should know about.

Today we carry out most of our daily tasks with the smartphone in our hand. That includes photography too. In recent years, improvement in camera quality has taken the center stage among many manufacturers and it shows. Today even an entry level smartphone can take satisfactory image given enough light, because low light imaging prowess is still reserved for the top of the line Flagship smartphones. Even in bright light, smartphone cameras can sometime have difficulty with the dynamic range of some challenging scenes. This is mostly due to the limitation of the smartphone camera sensor. I will talk about camera sensor in another article.

HDR – What is it?

HDR stands for ‘High Dynamic Range’.  As the name implies, it is higher than normal Dynamic Range. Dynamic Range is the difference between the darkest and lightest tones in an image. Generally DSLR cameras naturally have great dynamic range due to the large image sensor. But in smartphones, due to the size limitation of sensor, additional help from software is necessary. Simply put, an image with great dynamic range will have a good amount of contrast and will appear livelier whereas an image with a not-so-great dynamic range will appear dull.

Why is it needed?

There are two main factors that greatly affect image quality. These are overexposure and underexposure.

First up is overexposure. What it means is that the amount of light that hits the image sensor is greater than it should be. So the resulting image is much brighter than it should be. The below photos explain it.

Example of overexposed images

Image Source: Google

In the above images, you can clearly see that the images are too bright. Because of this, the details of the subject are lost.

Next up is underexposure. As you may have guessed, it is the opposite of overexposure. In this scenario, the light hitting the image sensor is lesser than optimum. So the images are darker than it should be.

Example of Underexposed images

Image Source: Google

As seen above, the images are darker than intended and due to this, the details in the shadows are lost.

How it works?

A large image sensor natively has great dynamic range. In smartphones, for combating the above scenarios, the software lends a helping hand. The technique used for this is Multiple Image Stacking. The phone takes a series of images that include underexposed and overexposed images. Then by using software algorithms, it merges these images to give us an almost pefectly exposed image. When we use this mode, it helps us in retrieving details in shadows(dark part of image) and also prevents from clipping of highlights(bright part of image).

The below images show how its done

Image Source: Google

End Result

So after the image processing is done, we can clearly see the differences in image quality. Please look at some samples posted below.

Image Source: Google

As you can see from the images above, the difference is like night and day. It really improves the image quality.

Pro’s and Con’s

Pro’s:

  • HDR image technique really brings out the details in photos that would otherwise be lost
  • Its a simple way to enhance the quality of the photo and these days, even entry level smartphone has this option
  • Due to the very nature of this technique i.e taking multiple images and then stitching it together, in some situations, it can even help us to take better low light shots with less noise and more details.
  • It somewhat mitigates the sensor size limitation of smartphones
  • Once we learn when to use it, we can get some breathtaking landscape shots

Con’s:

  • It’s not always perfect (Nothing in this world is :)). Using it in scenes where the image is already exposed properly can lead to some artificial looking effects. It can also cause halo effect where a bright white outline is formed around the subject.
  • Some manufacturers design the software algorithm in such a way that whenever HDR is used, the color saturation levels are pumped up to almost cartoonic levels hence providing us with an unnatural image. This was observed in my Oneplus One.
  • One main disadvantage of using HDR is the time it takes to capture and process the image. This problem is mainly prevalent in entry level and mid-range smartphones. Due to this delay we cannot take photos in quick succession. Also due to slow processing speed of HDR images, it really isn’t effective for moving objects as the end result may suffer from motion blur and other artifacts. But high end smartphones such as Google Pixel 2 and Samsung Galaxy Note 8 have the firepower for blazing fast HDR shots.
  • We need to know when to use it. Again in high end smartphones and even in some mid-range models, we have an option called auto-HDR where the phone analyzes the situation and decides whether to use it or not. Some phones even have live HDR effect viewfinder where the effect can be seen even before we capture the photo.

 

So this was my article on one of the most important photography techniques in smartphones. If you like this article, please share and also please check out our other articles. If you don’t, we appreciate constructive criticisms which will help us to improve. Also please feel free to subscribe to our Newsletter for receiving the latest updates.

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KANNAN S.NRenganathanSaravanan Sundaram Recent comment authors
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Saravanan Sundaram
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Saravanan Sundaram

Aswin,

As a layman, I did understand and appreciate HDR Photo.

Please keep educating us.

Thank you,

Saravanan Sundaram

Renganathan
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Renganathan

Good one Aswin….
Knew a lot about HDR… In simple language
Thanks

KANNAN S.N
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KANNAN S.N

Hi Aswin,
Explained well withexamples for better understanding. Very useful tips for smartphone users.
Best wishes.