Why do my HDRs look grainy?

[OptimusPhoto]

Hi all,

I have recently started to experiment with HDRs but I'm curious as to why mine look so grainy. I'm using a Canon T4i with bracketing -1,0,+1 with a 10-22mm lens and a ISO of 100. I'm using a tripod and compiling them in Luminance HDR. Am I not using the software correctly? Is there a better software to use? Please let me know.

Thanks.

[Colin Southern]

HDR is a set of techniques for capturing - in parts - a scene who's dynamic range is too big to be captured cleanly in a single exposure. Most modern DSLR cameras have a potential dynamic range capability (at base ISO) of around 12 stops so bracketing a scene +/- 1 stop (like you have) doesn't really do much.

The number of shots in your exposure bracket is going to depend (somewhat) on the camera, ISO, and (mostly) on the dynamic range of the scene you want to capture -- the acid test is to look at what you've captured and confirm that the over-exposed shots have good shadow detail (preferably as low midtones) and the under-exposed shots have good highlight detail (preferably as high midtones). You can't have too wide a range of shots for a bracket, but you can certainly have not enough -- as sounds like has happened in your case (best guess -- you really need to post an example).

My advice is to shoot your bracket at least 2 stops apart. Normally I'll shoot a 5 bracket sequence, 2 shots apart (so -4, -2, 0, +2, +4) (or -5, -3, -1, +1, +3) (or even a 3 stop bracket -- -5, -3, 0 -- don't assume that it has to be symmetrical). You really need to examine the shots after you've taken them and take a look at the histogram.

Other than that, not a lot I can say until I see some of the shots. On the face of it though, sounds like you're not capturing enough shadow detail cleanly, so noise is being revealed as a result of the range compression during processing.

[HaseebM]

I too have recently started experimenting with HDR, mainly as I am trying to chose between Photoengine & Photomatix Pro 5. On the lines of Colin's suggestion I took five bracketed shots but instead of manual, I chose Av. So far I have been fairly successful in reducing or keeping noise to a minimum especially since I let the Av decide on the exposure and keep the ISO at 100. Maybe you could try with Av, 5 bracket at ISO 100.

[ajohnw]

Luminance hdr can be a funny package to use. If you run Linux for instance search for MacroFusionEnfuse, your repo is bound to have it as well or if Windows/mac use this one

http://software.bergmark.com/enfusegui/Main.html

The various settings don't have conventional meanings - they adjust the weighting of the various factors used to pick information from each of the images. Default settings are usually fine. I'd suggest feeding the application with jpg's. In some ways if the tones are exposed well as described by Colin there isn't much point in using raw unless each is adjusted. Raw conversion would have to be done separately anyway.

This package wont provide an HDR look though. If you want that other routes are needed.Maybe the one in Rawtherapee if you want to use a free application but it will only give an HDR look to a single image - maybe one produced by Enfuse from several. On Linux Fotoxx has an interesting way of blending HDR images. I don't know of a Windows/Mac application that offers this approach. It uses layers but they are hidden from the user.

Expect to have to do some experimentation on what exposure levels to combine but I suspect any package will need that. I initially had a play. Just sited the camera in a north facing room with a lot of shadow - garden and a bright sky outside through the window and went on from there. There is a problem with this sort of HDR and others - a breeze might move things around between shots so they don't align. Tricky as it means only a single shot can be used for some of the detail levels - that needs manual work with layers and again no HDR look unless it's applied on purpose.

John
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[Colin Southern]

This package wont provide an HDR look though.

There's no such thing as an HDR "look".

HDR is a technique for managing dynamic range, not one for producing any kind of look.

[tao2]

There's no such thing as an HDR "look".

HDR is a technique for managing dynamic range, not one for producing any kind of look.

There's no doubt there's an "HDR look". It's obvious in so many photos on so many sites. It's that - explosion in a paint factory, paintball, soft, impressionist painted or freshly shot-blasted, over-enthusiastic application which gives HDR such a bad name. As in all things photographic, less is always more - except for HDR enthusiasts who appear tae think that more is never enough...

But then, they could always blame tone mapping....

[pnodrog]

Irritating isn't it Colin.

Theoretically a well done HDR will not exhibit a specific look even though we may realize from our experience with lighting and exposure that it must have been used. Unfortunately there is a look that stems mainly from the miss use of HDR/tone mapping either deliberately for effect or mistakenly due to a heavy handed or unskillful approach. There are some photographs that look very effective in a style we now call HDR but like posterisation and many other techniques unless it is appropriate and adds to the photograph it is often just looks like a poorly taken photograph that the photographer has tried to make look more interesting.

[Colin Southern]

There's no doubt there's an "HDR look". It's obvious in so many photos on so many sites. It's that - explosion in a paint factory, paintball, soft, impressionist painted or freshly shot-blasted, over-enthusiastic application which gives HDR such a bad name. As in all things photographic, less is always more - except for HDR enthusiasts who appear tae think that more is never enough...

But then, they could always blame tone mapping....

No no no no no - and a thousand more no's. That look has NOTHING to do with HDR - zilch - nada. You can get exactly that same look from a single frame.

I call that an "ultra tone-mapped look".

Think of it this way - if HDR had a "look" then by definition, any image that didn't have that "look" couldn't be HDR, which obviously isn't the case. I've used HDR in many images, but you'd never know it because the end result looks much the same as an image processed from a single exposure.

Sorry to be do pedantic about this, but if I don't jump on things like this then the misinformation keeps getting regurgitated, which doesn't help anyone in the long run.

[Richard Lundberg]

Forgive me for asking, but what is the point of HDR. The increased dynamic range can't be displayed or printed.

[Colin Southern]

Forgive me for asking, but what is the point of HDR. The increased dynamic range can't be displayed or printed.

The increased dynamic range that's captured is mapped into a normal dynamic range for display or printing. The resultant image is always normal dynamic range, but will contain information that was previously undisplayable or unprintable.

This HDR image of mine is a good example; it's shot into the morning sun, so the frames that expose the cloud correctly leave the foreground black and devoid of most detail. The frames that expose the foreground correctly have completely blown skies. HDR gives us the benefit of the best of both worlds.

[pnodrog]

Forgive me for asking, but what is the point of HDR. The increased dynamic range can't be displayed or printed.

Yep - as Colin explained in his first reply in this thread. The resulting image has a compressed/reduced dynamic range and is not HDR but the source was. Also there is no need for the resulting image to exhibit the odd tonal arrangement that some people refer to as HDR.

P.S. I see while I was typing Colin has illustrated with a natural looking image derived from a HDR scene.

[Colin Southern]

Irritating isn't it Colin.

Theoretically a well done HDR will not exhibit a specific look even though we may realize from our expedience with lighting and exposure that it must have been used. Unfortunately there is a look that stems mainly from the miss use of HDR/tone mapping either deliberately for effect or mistakenly due to a heavy handed or unskillful approach. There are some photographs that look very effective in a style we now call HDR but like posterisation and many other techniques unless it is appropriate and adds to the photograph it is often just looks like a poorly taken photograph that the photographer has tried to make look more interesting.

Irritating? No no no ...

... OK - yes - extremely irritating!!!

Keep in mind though that it's only called "HDR" if we let it. That's why I jump from a great height on posts that refer to the "HDR" look. Case in point is my image above; produced from a 5 shot bracket - definitely HDR, but no "Harry Potter on drugs" look to it. In contrast we have an image like the one below that I've over-processed to look a bit like what people are talking about - shot from a normal dynamic range single exposure.

I just really really really really want people to try and disassociate the hyper tone-mapped look from an HDR "look" - they're not particularly related.

[tao2]

No no no no no - and a thousand more no's. That look has NOTHING to do with HDR - zilch - nada. You can get exactly that same look from a single frame.

I call that an "ultra tone-mapped look".

Think of it this way - if HDR had a "look" then by definition, any image that didn't have that "look" couldn't be HDR, which obviously isn't the case. I've used HDR in many images, but you'd never know it because the end result looks much the same as an image processed from a single exposure.

Sorry to be do pedantic about this, but if I don't jump on things like this then the misinformation keeps getting regurgitated, which doesn't help anyone in the long run.

Hi Colin,

Yes,yes,yes,yes,yes - and x number of yesses. The perception of a great many folk is that your second image (and the millions of images on the web, in that fashion), is HDR. Ah don't think that ah'm misinforming anyone by pointing that out? Perhaps you only read my first sentence? Ah went on tae say...

It's that - explosion in a paint factory, paintball, soft, impressionist painted or freshly shot-blasted, over-enthusiastic application which gives HDR such a bad name

Ah completely agree with all you said above but the evidence is out there. There are thousands of " HDR Photography" sites which have as much in common with HDR as ah have with David Cameron...

[Colin Southern]

Ah completely agree with all you said above but the evidence is out there. There are thousands of " HDR Photography" sites which have as much in common with HDR as ah have with David Cameron...

As you say - there are thousands of "HDR Sites" and the "evidence" is out there - but that still doesn't make it correct, any more than it makes Boab Smith the prime minister of Britain.

Point is - if we don't make a stand and challenge things like this here - then surely we're no better than all the misleading sights?

Not on my watch! I'd rather be the one who gets it right than the one who's in agreement with the masses.

[HaseebM]

I think the point Tao is trying to make ( and I agree with him ), there is a 'hdr look' to images once they are bracketed and processed. Your image of the house has that look whether you agree or not. What you are saying maybe technically correct and the reason HDR software gives us options to process them more natural, photographic or painterly etc.,

[ajohnw]

Jump on me by all means Colin but I will continue to call it an HDR look. Some cameras are obtaining it internally automatically, calling it HDR and some people love it. Shout at them too. My favourite description is cartoon colours. If it caught on it might prevent people from using it so much.

:-) Enfuse doesn't do it that way anyway. It's aim in life is to produce images like the one of your parents place that is an excellent example of what can be done. You haven't even over augmented the clouds. People just love doing that.. Some one posted a shot of pier I used to fish off recently. My only thought when I looked at it was great shot of the pier - processed obviously as were the clouds, too much in my view but an immediate comment was "I would make more of the clouds". Then in other areas we get comments about distractions away from the subject. Seems that doesn't apply to clouds - and other things at times.

Then there is the term tone mapping. I have seen that described as a process of mapping one tone to another. That's how I read it anyway some where on adobe's site talking about low level raw processing aspects that customers needn't worry about. A more usual description is something like "Tone mapping reduces global contrast in images while increasing local contrast and shadow/highlight detail" The last part of that isn't usually included and probably isn't correct other than contrast will be changed in that area as well.

Not long after I joined this forum there was a very long HDR thread - must use tone mapping and all examples posted had cartoon colours. It seemed to be considered as something that must happen when tone mapping is used in global contrast .......... way To be honest I have no idea how that style of tone mapping can be used to merge images. What the poster who said that probably meant is the other meaning - mapping one tone to another but why the cartoon colours unless they are applied on purpose.

Unfortunately the English language is full of context sensitive words. I had a German roll around laughing when I explained all of the meanings a simple work like tap could have. Me - I pitied the man when I found out the word he needed to use to name the type of tap that is used to produce threads in a hole so that it can accept a bolt - yet another bolt. Screw too is another one that has even changed with times not that I would use that on you.

John
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[dubaiphil]

I think it's a case of HDR methodology being utilised in a certain way to produce an effect, and that effect gaining a cult following. That effect is certainly not to everyone's taste. Used as a form of blending multiple exposures to finalise an image as the photographer viewed and remembered the scene at the moment of capture is the original methodology and is a very useful tool to have in one's software and skills 'bag' to draw from when necessary. If the photographer wishes to take things to the max and over saturate and over structure their final image then that's totally up to them. That look constitutes the 'HDR look' that some posters are referring to.

However in my mind the 'HDR look' should not be noticeable at all. Used sparingly and in a lightly spiced format is where I use it to bring out shadow details. If you want to go down the full on Phall route rather than my Korma variety then go for it.

An analogy - the 'Tilt Shift Look'. Using a tilt shift lens in exactly the opposite way to that which it was originally designed in order to miniaturise a scene, exaggerated further in post with selective saturation. Certainly not what tilt shift lenses are made for, certainly not to everyone's taste, but a different form of photography using available hardware and software creatively. Whether that creativity is tasteful is subject to the individual.

Skiing vs. snowboarding

Now I'm going to go completely off piste and try my hand at free lensing. Until that becomes too popular

[pnodrog]

The example below is an example of a 5-6 stop difference in exposure between the exposure for the cave and the outside exposure and a bit more for the waterfall. A true HDR situation using just two exposures blended together using layer masks and individual adjustment layers in photoshop. Any so called HDR effect has been avoided as much as possible. I just wanted to convey the impressions I had of the scene.



Unfortunately our eyes lie to us by automatically adjusting to and changing our impression of the lighting levels as they scan a scene in real life.

[dabhand]

Now whilst most people seem to accept a digital image can be created using Ansel Adam's style / techniques, which to the pedant would be illogical seeing as AA used film and chemicals, the mere mention of HDR seems to create a storm of 'correctness'.

To me it's quite simple, people are generally not pedantic in communicating, else 'hoover', 'biro' etc would not be in common usage - I can't quite see my wife saying "run the Dyson DC25 multi-floor around...". Even the term HDR is itself one of the commonly accepted terms as it really should be HDRI - High Dynamic Range Imaging.

When it comes to discussing the apprearance of an image, the majority (rightly or wrongly) of photographers now seem to have accepted that 'hdr' creates a specific end result, though if 20 photographers were to be asked to specify in finite terms what their interpretation of 'hdr' was, there would actually be 20 different variations.

For those new to HDR (or HDRI if I'm to be pedantic - heaven forbid) or those wanting to get a basic understanding of the technique, I suggest they consider looking up the websites of Klaus Herrman and/or Blake Rudis.

steve

[Colin Southern]

When it comes to discussing the apprearance of an image, the majority (rightly or wrongly) of photographers now seem to have accepted that 'hdr' creates a specific end result

The big problem that I have though Steve, is that when people start to distort the meaning of things like HDR it makes it much harder to effectively communicate knowledge to them; we get people posting ultra tone-mapped images - calling them HDR - and then telling us that they were produced from a single frame. And we get people who have the need for true HDR to overcome a DR limitation issue, but they're unreceptive to the suggestions because they think if they use HDR then their images will look like a Harry Potter nightmare.

The bottom line is - for me anyway - the more we allow misconceptions like this to stand, the harder we make it to help these people, and the less effective we are in helping them. In essence it becomes a major time-wasting exercise to have to undo the damage first, and then re-educate them from the beginning. And frankly, I'm starting to wonder why I'm bothering to give up so much personal time to pass on hard-earned knowledge when there seems to be so many working against me; but I digress ...