Most of the DJI products have the histogram in DJI GO application, but do we really need it?

First of all we have to turn the histogram on:

1: Start the DJI Go APP

2: Enter the camera view

3 : Tap the Menu

4 : Select the Settings

5 : Histogram on

The histogram is a useful but often misunderstood tool that the DJI GO app provides to help you get the correct exposure on your images.

In this article we’re going to look at how to read it and use it to your advantage to help you do just that.  Getting the best exposure (there is not such thing as the “correct” exposure, as it’s all subjective) in camera should be your goal every time you click the shutter.Using these tips should help you increase your success rate with land and areal shots.

What is a histogram?

Dictionary definition:   A bargraph of a frequency distribution in which the widths of the bars are proportional to the classes into which the variable has been divided and the heights of the bars are proportional to the class frequencies.

HUH?!  Anyone else confused?  But what does it do?  How do you read it? Let’s have a look!

How to read the Histogram?

A histogram is a graphical representation of the pixels exposed in your image.  The left side of the graph represents the blacks or shadows, the right side represents the highlights or bright areas and the middle section is mid-tones (middle or18% grey).  How high the peaks reach represents the number of pixels in that particular tone.  Each tone from 0-255 (o being black and 255 beingwhite) is one pixel wide on the graph, so imagine the histogram as a bar graphall squished together with no spaces between each bar.  Have a look at the diagrams below:

What can we learn from this histogram?

There are many things we can learn about an image just by looking at the histogram.

We can tell an imageis well exposed if it reaches fully from edge to edge without a space on oneside of the graph, and isn’t heavily going up one side or the other.  In an ideal world, it should just touch the left and right edges, and not spill up the sides, with a nice arch up in the center.  However, that doesn’t always apply in every situation, for every scene.  Here are a few examples:

＊ This is a histogram for a light subject (light sky ) with mostly light tones in the scene and few dark areas. See how it is shifted to the right now versus the dark subject. This is correct.

＊This is a histogram for a dark subject, it is not wrong it is just more shifted to the right to represent the tones of the subject. This might be a dark forest, shadows or the any other dark object

＊ This is how an ideal histogram might look, evenly distributed, edge to edge, not up the sides

When the histogram tells you to adjust your exposure?

Gaps on either end indicate you are missing information and your exposure can be shifted safely without losing detail.   When your graph is shifted too far in one direction or the other so that it does not even touch the other edge – that means you can safely shift your exposure to cover more of the range of tones. Let’s look!

＊ Now we see a gap on theright side of the graph indicating there are no whites represented so the image will be dark, too dark. You can safely give the image more exposure until you see the graph just touch the right edge

＊ This graph shows an overexposed image, notice the gap on the left side indicating a lack of any blacks represented. It also means you will lose lots of detail in the white areas that may not be recoverable. In this case shift to give your image less expo

Summary

By using the histogram on your aircraft camera, it is easier to see how to adjust your image exposure.  There is a lot more to know about the histogram, and you can use it when you process your images in Photoshop or Lightroom as well. Keep in mind that if you shoot JPG format, nailing the exposure in camerais even more critical.  If you shoot RAW format you have some leeway to make adjustments later, but it’s still a better idea to get it right in the first place.

Nice overview DJI-Tim!

After having shot several images that later (behind my PC)  turned out to be to dark,  I am used to display the histogram on the App.
In this overview there should be some examples?
They all seem to be missing.

rene.vandermeer Posted at 2015-11-25 20:03
Nice overview DJI-Tim!

After having shot several images that later (behind my PC)  turned out to be ...

Yeah! Thanks to histogram inventors)
Sorry, that the thread is missing pictures right now, i'll fix it

Well stated and to make things simple, peaks to the left under exposed, peaks to the right, over exposed. Peaks in the center correctly exposed. There are times that you can have all three which is acceptable. If you have shadows in the exposure you will have a small peak to the left and vice versa, a small peak to the right can be a bright reflection. As Tim states, the higher the peak the stronger the source of light.

rodger Posted at 2015-11-25 08:09
Well stated and to make things simple, peaks to the left under exposed, peaks to the right, over exp ...

Even with your Phantom sitting on the ground, you can get a  helpful idea of how the histogram works.

First, it's a good idea to make sure your camera is pointing either slightly up or straight out. Get it out of tall grass onto a piece of wood, on top of your transport case, whatever. You're not going to take off, so don't worry if there's a lot of metal involved.

Press the appropriate menu and turn the histogram on. For those of you who've never seen the histogram before, it will appear (by default) in the middle bottom of your display (someone correct me if it shows up differently on your device).

Using the wheel on the right side of your controller, either rotate the wheel slowly, paying attention to both the display of what your camera is seeing and the histogram. You may have to press the wheel first (it also acts as a "button switch" before you get any response to the view/histogram.

By watching the display lighten or darken, notice that the histogram will also react to the view getting lighter or darker. The main concept, as Tim already pointed out is to get as smooth a distribution of the histogram as is practical. If the "bars" are all smashed up against one side or the other, you're going to end up either overexposed or underexposed. When the bars are pretty evenly spread out, you'll get as close to the perfect exposure as is possible.

As a sometime amateur photographer, the purpose of the histogram is not so much to get the perfect exposure (sometimes darn near impossible). It's more important to see whether you're grossly underexposed (very dark) or grossly overexposed (very light). If you get your exposure "...in the ball park..." it can make it much easier to fine tune the photo/video with your editing software.

If it's way out of whack to begin with, you may easily discover that fine tuning is darn near impossible. The histogram can be used as a quick tool to verify that you got your exposure "...in the neighborhood..."

One major caveat - If you're shooting situations where there's a good-sized patch of either dark or light in your scene, you'll get "holes" in the histogram. For example: if you're shooting a real estate type scene (someone's house) surrounded by lots of trees, but the house has a white tiled roof, the histogram may think the center is overexposed. Or it might think the edges of the photo are underexposed. With many (if not most) modern cameras, you can typically point directly at one part of the picture to set whatever exposure level you want, then take the picture. This is pretty straightforward with most digital SLR cameras. It may be a little tougher with your Phantom. Just remember that the histogram is a guide - not the absolute answer every time.

Thanks Tim.

Art - N4PJ
Leesburg, FL

rene.vandermeer Posted at 2015-11-25 06:03
Nice overview DJI-Tim!

After having shot several images that later (behind my PC)  turned out to be ...

This is why photographers go to a LOT of trouble and expense to calibrate their monitors and printers.  If your monitor is not calibrated, someone else may display your images/videos completely differently that you do.  It's even more complex when you print or send them to a commercial printer.

Another Good thread, thanks again @DJI-Tim.
I think it's MARVELOUSLY awesome that you guys are taking a seemingly much more proactive position, with our @DJI  gear!! Thanks for this.
The constant improvements and firmware additions to our already incredible gear is worth mention, again. Much appreciated by this consumer.

I do also look forward to This next firmware update. ;-)
And any forthcoming ones as well. Hehe

RedHotPoker

I finally fixed this post! Now it's readable, and has pictures in it{:3_52:}

rodger Posted at 2015-11-25 23:09
Well stated and to make things simple, peaks to the left under exposed, peaks to the right, over exp ...

Not quite as simple as that Roger, it's a distribution of pixels intensity values as Tim's explanation very accurately says.
So peaks either side or in the middle don't mean under or over exposed. To use an extreme example, a correctly exposed picture of a chequered flag will have peaks at either end and nothing in the middle. So the distribution only has context with respect to the image you are viewing.

Nice Work Tim!

Rule of thumb for digital photography...
Expose for the highlights (you can bring the rest up in post processing).

Great Work!! Thanks for your time and help!

Hats  off to you Tim, keep up with the good work. Thanks for your dedication.

mike.wildlight Posted at 2015-11-26 03:13
Not quite as simple as that Roger, it's a distribution of pixels intensity values as Tim's explana ...

Mike, I do not disagree with you or Tim. Both of you are correct. My point is "as a rule of thumb" to obtain a useable photo. Blacks (shadows) are too the left and Whites (highlights) are to the right. The height is as stated by Tim is the number of pixels. If you "Google" Histogram in Photography you should find a Wikipedia definition and there is a thumbnail of an ideal exposure depicting the overall exposure is in the center. My intention was to simplify the use of the Histogram.

aburkefl@gmail. Posted at 2015-11-25 09:33
Even with your Phantom sitting on the ground, you can get a  helpful idea of how the histogram wor ...

A more detailed description of my short description. I am not disagreeing with Tim or anyone else. It is a great aid. The Histrogram is a great tool for HDR Photography in that as stated the Highlights = the right and the shadows = the left. If I want to expose for the highlights I lean to the right, the shadows left.

You mention tall grass. Green grass is a great reference for an average exposure. Not meaning having the camera in the grass but, once in the air at height and using it to grab an average useable exposure. Close to a Grey Card.

http://youtu.be/jX45Yi1spY4

Thanks for info!

complicated, but something to learn, thanks.

Thanks Tim

Nice work pulling this together Tim, very helpful.

Excellent info, thanks Tim!

Barney

Great Work

Used it for years in Photoshop and is a must tool among many.  Its a great example.

Thank you guys for your positive feedback!

After nearly pulling out my last hair in post production with my DSLR about 10 years ago, I called my uncle who is a semi professional photographer and asked him to come and help me.  The first thing he asked was "Was I using the histogram prior to snapping the shutter?"

I responded, "The what?"

After that experience and trial and error, my post production for all digital stills has decreased dramatically.  It cannot be argued that a histogram is useless.  IMHO it should always be displayed when shooting stills.  As for video, I can't comment.  I haven't enough experience with that, plus the graph will be ever changing, so I do the best I can and move on.

Really helped me understand this. Been wanting to learn how to use it for a while now. Thanks!

This is very helpful

Tim, Thanks for the information!

Nice info dudee. I try later...

vin_skyline69 Posted at 2015-12-16 09:52
Nice info dudee. I try later...

I always keep it on!

Great overview DJI-Tim!

rodger Posted at 2015-11-25 21:09
Well stated and to make things simple, peaks to the left under exposed, peaks to the right, over exp ...

Good way to  simplify it

DJI-Dave Posted at 2015-12-27 09:43
Great overview DJI-Tim!

Thanks Dave!

rodger Posted at 2015-11-26 07:47
Mike, I do not disagree with you or Tim. Both of you are correct. My point is "as a rule of thumb" ...

I find it best to keep the histogram as far to the right as reasonably possible even if some highlights are slightly blown. Some over exposure is not only acceptable but desired. By doing this you can keep noise to a minimum. It is always easier to recover detail exposed to the right, with less noise, then pull from blacks. Usually you cannot recover specular highlights anyway and will not notice if blown.

Of course just personal preference.

Butch

daviskw2004 Posted at 2015-12-27 13:06
I find it best to keep the histogram as far to the right as reasonably possible even if some highli ...

The whole "expose to the right", "expose to the left" thing just creates confusion in my view.
Expose for the highlights doesn't mean under-expose so the whites appear grey, it means expose so there are no noticeable areas of lost data in the highlights, many cameras will indicate this in some manner. I understand that some camera sensors have varying performance in dynamic range. But as a rule of thumb this will serve the majority of people well for an initial exposure.

daviskw2004 Posted at 2015-12-26 22:06
I find it best to keep the histogram as far to the right as reasonably possible even if some highli ...

I like t lean toward the lower side. I have done that for years with my Hasselblad's if you remember that film stuff. I like the saturation. I can remove from little bit of under exposure but not when it is blown out. True, whatever floats your boat.

Thanks tim

Thanks Tim!

great post

For those familiar with professional video cameras the histogram mimics the WAWEFORM MONITOR these cameras have. The only difference is that the waveform monitor displays black at the bottom and whites at the top being gray everything else in between. Waveforms are more precise than histograms  but equally essential for exposure detail.

DJI-Tim Posted at 2015-11-25 20:23
I finally fixed this post! Now it's readable, and has pictures in it{:3_52:}

Could you please explain {:3_52:}?