# is this hdr?



## bribrius (Mar 10, 2014)

going through the hard drive. i took a few hdr. in camera. Thinking this is one of them. it is "okay".
notice the white around the building edges though. color seems a little off. something not quite right.
so, a. is the one of the hdr ones? sadly im not even sure i was playing with 3d too.
b. why does it look messed up?

View attachment 68339


----------



## bribrius (Mar 10, 2014)

how do i get rid of that white line around them?????????????????????????????????????????????????????????????????????????????????????


----------



## bobandcar (Mar 11, 2014)

The only white line I see is on the dark building on the right side. Seems that it is a reflection of the sky on a smooth part of the building.


----------



## MOREGONE (Mar 11, 2014)

I would venture that yes that is an in-camera HDR image. I am not sure how to edit the image to your liking. Maybe bring back the shadows that HDR tries to lighten?


----------



## Gavjenks (Mar 11, 2014)

It is usually impossible to tell if a photo is HDR simply from looking at it.

The only way to tell would be if just life experience tells us that in such a scene, the dynamic range would HAVE to be beyond the camera's abilities, and yet the image shows it easily covered. For example, a glaring sunset without blocked shadows or blown highlights.

A typical gray day in a city is not an example of such a "must have been HDR to possibly pull it off" situation, and thus is impossible to tell for sure by eye.


----------



## Light Guru (Mar 11, 2014)

Gavjenks said:


> It is usually impossible to tell if a photo is HDR simply from looking at it.



In this case that is true but with what most people do to HDR it is horribly obvious.


----------



## MOREGONE (Mar 11, 2014)

Gavjenks said:


> It is usually impossible to tell if a photo is HDR simply from looking at it.



I would correct that to "It should be difficult to tell if a photo is HDR when done properly"

But "usually" not even close. Most HDR photos you can tell. And "impossible"? I definitely wouldn't make that claim, especially after explaining how to figure it out.


----------



## Gavjenks (Mar 11, 2014)

Light Guru said:


> Gavjenks said:
> 
> 
> > It is usually impossible to tell if a photo is HDR simply from looking at it.
> ...


That's tonemapping that makes it horrible obvious, usually, not HDR. HDR just makes the whole image grayer and extends the blowout range and by itself looks almost no different than if you simply took a single exposure with a higher dynamic range camera. Tonemapping is a separate step (which doesn't actually even require HDR ahead of time) that is responsible for all the obvious stuff: cartoonnishness, halos around stuff, weird unnatural looking bright/dark patchy patterns, etc.


----------



## manaheim (Mar 11, 2014)

That's the customs house.  Are you in Boston?

If that's HDR, it's not a great example of one.  Not a lot of dynamic range.


----------



## Gavjenks (Mar 11, 2014)

> If that's HDR, it's not a great example of one. Not a lot of dynamic range.


Again, you can't tell how much dynamic range something has just by looking at it, if you don't know the lighting conditions at the time the photo was taken...

You sound like you live in the area and thus might have some knowledge of typical conditions, okay, but it still could have been a particularly harshly lit, backlit day where the black building was inky black and the sky was blinding white, OR it could have been heavily overcast with much less of a difference.

In either case, you could use HDR or not to achieve precisely the same looking final image, but the two would have dramatically different dynamic ranges, since they would be encoding a very different ratio of absolute lightness limits from the scene.

Dynamic range does not refer to how gray the image is (that's simply "contrast"). It refers to the difference in actual luminance in the scene in the real world when the photo was taken, between the object that produced the darkest black that you can discriminate in the final image versus the object that produced the brightest white you can discriminate in the final image. As in, the ratio between the number of photons that were coming off of that black building per square meter versus from the sky ON THAT DAY (if either was blocked out or blown out, it wouldn't count though)

Contrast and DR are independent of one another: either can be high or low while the other is high or low.


----------



## manaheim (Mar 11, 2014)

Hmmmmmm... I'm trying to wrap my head around this but my brain is telling me that dynamic range contributes rather significantly to contrast. Maybe I'm losing it.

Anyway... yes, I do live in the area, and I'm very familiar with the customs house.  Taken from one particular angle you can pretty much never  get any sun on the damned thing. This is not that angle, though.  Regardless of that... what I see is an image where everything is pretty evenly lit.  All of the buildings in the frame have pretty much the same light, and it appears that the sun is coming from the left. And it doesn't look overcast.

No, I suppose I can't be sure, but this looks like an HDR that just wasn't all that well done. (no offense to the OP, mind you... practice makes perfect)


----------



## Gavjenks (Mar 11, 2014)

It is indeed confusing. Let's use an example. Let's say you shoot a scene of a forest. There's a rock in the scene that is in shadow and is the darkest part of the scene. There are some leaves that are the brightest part. Each area has an actual luminance in the real world. Let's say for sake of simplicity:
Rock = 10 photons per pixel it takes up on your sensor per second.
Leaves = 160 photons per pixel it takes up on your sensor per second.
The dynamic range of this scene is 4 stops (160 / 10 = 16 = 2^4).

Let's say your camera is capable of capturing up to 4 stops of dynamic range. Any scene with more than that will have clipped shadows and/or highlights no matter how well you choose your exposure. Anything = or less than that will show all detail with no clipping. You can take this image without HDR, and capture all the detail. Like this:



The above image, in the situation described, has a dynamic range of 4 stops.

Now let's say the lighting conditions in the actual forest were different. Let's say it was like this:
Rock = 20 photons per pixel it takes up on your sensor per second.
Leaves = 1280 photons per pixel it takes up on your sensor per second.
The dynamic range of this scene is 6 stops (1280 / 20 = 64 = 2^6).

Now you need HDR if you want to capture all the detail in the scene with your 4 stop camera. A center-metered (what your camera will tell you to do) shot would give you the middle 4 stops, and clip one on each side. That would look bad. It would look like this:

This is still a 4 stop dynamic range image, but the ends are clipped now, and you lost the detail in leaves and rock, because the dynamic range of the scene was 6 and you only captured a portion of it this time.

So instead you take one photo at -1 stop, and one photo at +1 stop. Giving you 2 stops overlapping and two at each end covered by one shot each. You plug this into software that gives you basically just a photo that looks like you used a camera.

+1 capture (4 stop dynamic range image):

-1 capture (4 stop dynamic range image):


Output of software:

This is exactly the same final image, but it has a dynamic range of 6 stops now, versus 4. Because the rock in the actual forest put out 6 stops less light than the brightest leaves, and you captured that range precisely in both scenarios.

So the final image (and its contrast) are identical, but the dynamic ranges aren't, and one required HDR techniques, and one didn't. Just had to do with how harsh the light difference was in the forest.

Now, on the other hand, you can change the contrast without changing dynamic range. For instance, using the curves tool like so:

Notice that the tool is only rearranging the middle lightness values. It isn't touching the blackest blacks or whitest whites (those fall on the original line of the starting image). Since dynamic range is defined entirely by the endpoints of the range, dynamic range is EQUAL here in this lower contrast image as it is in the image above it.



Dynamic range of the image here is defined as on the ratio of different rates of photons from the darkest and lightest areas *IN THE ACTUAL FOREST *from the most extreme items that your image didn't clip.

Simply by looking at the final image, though, you don't know if the actual forest had a low range, and it was a single shot, or if it had a wide range, but the photographer compensated with multiple captures to still get the full range.

High dynamic range is defined as doing things (like multiple captures) that extend the dynamic range of your images beyond what your equipment can "normally" / natively produce (i.e. with a single capture in the case of photography). So the 6 dynamic range image scenario with a 4 dynamic range camera = HDR. The identical 4 dynamic range image with a 4 dynamic range camera = not HDR.


----------



## Light Guru (Mar 11, 2014)

manaheim said:


> Hmmmmmm... I'm trying to wrap my head around this but my brain is telling me that dynamic range contributes rather significantly to contrast. Maybe I'm losing it.



Not always. Take a photo of a silhouette of a person. That photo would have no dynamic range but vary high contrast. 

You could also have a photo with great tonal range and yet vary little contrast.  For example this has great tonal range but no contrast. http://m7.i.pbase.com/u26/jackcnd/upload/43767517.GradientWhite720p.JPG


----------



## AlanKlein (Mar 11, 2014)

Looks like HDR to me.  There's little contrast; the brightness seems equal.  Colors seems strange too.


----------



## Bitter Jeweler (Mar 11, 2014)

I thought that clock looked familiar!


----------



## manaheim (Mar 12, 2014)

I get it. 

Bitter, that's an AWESOME picture of the clock. How did you do that? lol


----------



## DSRay (Mar 12, 2014)

For my two cents, the exaggerated blues and halos around buildings are tell tale signs of a poorly executed HDR process.


----------



## TreeofLifeStairs (Mar 12, 2014)

Gavjenks, what is the dynamic range of the human eye? It seems to me that any dynamic range larger that what we are used to seeing would look strange regardless of if it was HDR or not.


----------



## Gavjenks (Mar 12, 2014)

The eye works completely differently, it's very difficult to say.  

1) Your eye masks the image on the fly on a very small scale. It would be the equivalent of your camera changing the ISO individually for every pixel to adapt to each image.
2) You use semantic *life knowledge* to accomplish #1: Your brain knows that a chair is a chair and a cloud is a cloud and which one you need more texture and detail in, based on your current goals, and it will prioritize maximum visual signal accuracy in the specific portions of the image that are most important to what you WANT to see right now by adjusting those masks. This is obviously light years ahead of the capabilities of cameras with static programming and no connection to our brains.
3) You don't process a whole image at once. You move your fovea around and basically stitch half a dozen "frames" together whenever you look at a scene. Your brain is also adjusting the dynamic range for every one of those frames and fudging /readjusting the dynamic ranges in between / in past shots as you update the next ones in your scan.
4) Due to the whole life knowledge thing, a good chunk of what you "see" isn't even there. Your brain is just filling in what you expect to see in such a situation. What may actually be an inky black shadow with nothing in it, your brain might paste in some grass detail, etc. Cameras can't do this, because they don't know what they're looking at. Does that count as dynamic range if you use your imagination to avoid blowing a highlight? Unclear.

So does that count as "native" dynamic range? It's basically doing stuff like you do in software in HDR, but on crack / 10x more complicated. But it's also "normal" for that system. So it's very ambiguous whether you'd call it "HDR" or not, or "what the dynamic range of the eye is" (instantaneous one-shot flashed image dynamic range? Or heavily adjusted real world situation dynamic range? They differ by tens of stops)


----------



## bigal1000 (Mar 15, 2014)

bribrius said:


> going through the hard drive. i took a few hdr. in camera. Thinking this is one of them. it is "okay".
> notice the white around the building edges though. color seems a little off. something not quite right.
> so, a. is the one of the hdr ones? sadly im not even sure i was playing with 3d too.
> b. why does it look messed up?
> ...




Yes though a bad one ? By the way why are DSLR"s overrated ??


----------

