Some HDR photos.
05-10-2008, 11:13 AM
#42
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Originally Posted by Nick06tC
That is deffinetly what HDR is. But the pictures dont have to be RAW. They can be done in normal JPG format. But RAW is much much better. And its not exposure timing you adjust. You adjust the range of the aperture value. usually plus 1-2 steps in either direction from normal.
05-10-2008, 03:15 PM
#43
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Well here goes...
The process of HDR is to capture more dynamic range than one shot can handle. It's important to understand what dynamic range is before getting more of it. Technically it does not mean color, the range that is being referred to in HDR is the light to dark range, ie capture detail in bright areas as well as dark areas simultaneously.
The reason you have to snap multipel shots is that in an 8bit or even 10 bit image, you only have so many colors and brightnesses to work with. So usually a camera will evaluate the scene and try to choose the best range to represent what you are looking at. Often this means clipping out the brights or leaving out the dark areas.
For instance, lets say an shot has a birght light source as well as a dark shadow in frame. You could think of the range it covers as:
In other words areas of the picture cover that range of brightness.
Now your camera can only get this much range in one shot
|------------------|
so what does it do? It gets what it can so compared to the actual image it only captures a small portion of it, blowing out the brights and loosing image detail in the dark.
So you can see you will miss a lot of real image as the brights will all just be blown into "white" and the darks will all be lost into "black".
So when you take multpile frames at different exposures, then you capture all the range like this:
Now you can see you captured all the detail from the darks all the way to the brights.
Now you have to tone map it. And this is where HDR purists say you don't have an HDR anymore... you have a tone mapped HDR image. The reason is that while you still collected say 24 bits of data in your 3 frames, you will be eventually be showing them back on an 8 or 10 bit display... so it's not really HDR by the time you see it on your screen, because you only have the normal 8 or 10 bit display range.
But letting that asside, this kind of shows you what HDR is trying to capture.
Popping colors and crazy angry looking clouds are actually not what HDR is supposed to be about originally... the originaly point of HDR was to be able to show you natural looking scenes that have high range.
Your eye is very good at doing this, you can look at a sunset with the sun in front of you and still see detail in the ground around you and the clouds in the sky all at once.
On film this tends to be very difficult... you blow out close or sun or you loose ground detail into the darkness.
HDR helps alleviate this. A side effect of the processing is often that colors pop. HDR Purists will not like this, light blooms, color pops and anything that makes the picture look "fake" offend pure HDR fans.
The classic example of when to use HDR is standing inside your house on a bright day, take a picture through a window to the brightly lit outdoors.
Now try to do that and get whatever is out side your window to show up at the same time as the tables and chairs or whatever inside your room do.
This is pretty much impossible witha single shot. You either get the outdoors showing up, but the room completely blacked out, or you get the room to show up but the window is just a big white square that you can't see anythingi in.
Not the best result, but this gives you the idea of this in action
http://www.flickr.com/photos/jonatha...ol-truetonehdr
Here is another shot that does HDR well
http://www.flickr.com/photos/fersy/2...ol-truetonehdr
With a normal single shot, both of those would have had very dark areas or blown out white areas. It's tempting to say they don't look special at all, taht's just what you would normally see... but go try to shoot similar shots with a single from on a regular camera and you will start to understand what HDR is all about.
However some like the color popping and think that is what HDR means and thus strive for crazy colors and angry clouds. I personally say it's up to you. But hopefully here you will understand what HDR is about at least.
Oh and be careful messing with aperature to get HDR.... that is NOT A good idea. Changing aperature changes focal range and DOF. Getting 3 shots with different focal range and DOF means they won't look the same and when you blend them you will get weird blurines and incorrect image data. You wnat to LOCK y our aperature and change exposure to get your multiple exposures, not the other way around. You need multiple shots that focus the same, but have different brightness ranges.
What you want is called exposure bracketing. It changes the EV compensation automatically and snaps shots at multipel exposures for you. If you are on a tripod this eliminates the possiblity of movement between shots so your result will line up right. Be aware that often EV bracketing will be done by the camrea by altering the aperature. So put yoru camera in aperature priority mode, lock your aperature, and then snap away.
Also images do not have to be RAW, the reason some people like RAW is that a cameras sensor often can pick up 12 bits of data and dump it all into a raw file, then chop and compress the range to fit into an 8bit jpeg. Sticking with raw means that 3 exposures could cover up to 36 bits of range while 3 8 bit jpgs could only cover 24 bits... (you always overlap exposures so you won't ever get those numbers, but the point is).
Bear in mind many cheaper cameras these days (I am saying sub $500) do nto have sensors capable of much more dynamic range than a 8 bit jpg can hold... so going RAW on cameras witn sensors that don't really capture more range than the jpg can isn't nearly as beneficial.
The process of HDR is to capture more dynamic range than one shot can handle. It's important to understand what dynamic range is before getting more of it. Technically it does not mean color, the range that is being referred to in HDR is the light to dark range, ie capture detail in bright areas as well as dark areas simultaneously.
The reason you have to snap multipel shots is that in an 8bit or even 10 bit image, you only have so many colors and brightnesses to work with. So usually a camera will evaluate the scene and try to choose the best range to represent what you are looking at. Often this means clipping out the brights or leaving out the dark areas.
For instance, lets say an shot has a birght light source as well as a dark shadow in frame. You could think of the range it covers as:
Code:
Pitch black Staring at the sun bright |---------------------------------------------------|
Now your camera can only get this much range in one shot
|------------------|
so what does it do? It gets what it can so compared to the actual image it only captures a small portion of it, blowing out the brights and loosing image detail in the dark.
Code:
What there is:
|---------------------------------------------------|
And this is what your camera captures:
|------------------|
So when you take multpile frames at different exposures, then you capture all the range like this:
Code:
What there is:
|---------------------------------------------------|
What your camera captures:
Frame 1
|------------------|
Frame 2
|------------------|
Frame 3
|------------------|
Now you have to tone map it. And this is where HDR purists say you don't have an HDR anymore... you have a tone mapped HDR image. The reason is that while you still collected say 24 bits of data in your 3 frames, you will be eventually be showing them back on an 8 or 10 bit display... so it's not really HDR by the time you see it on your screen, because you only have the normal 8 or 10 bit display range.
But letting that asside, this kind of shows you what HDR is trying to capture.
Popping colors and crazy angry looking clouds are actually not what HDR is supposed to be about originally... the originaly point of HDR was to be able to show you natural looking scenes that have high range.
Your eye is very good at doing this, you can look at a sunset with the sun in front of you and still see detail in the ground around you and the clouds in the sky all at once.
On film this tends to be very difficult... you blow out close or sun or you loose ground detail into the darkness.
HDR helps alleviate this. A side effect of the processing is often that colors pop. HDR Purists will not like this, light blooms, color pops and anything that makes the picture look "fake" offend pure HDR fans.
The classic example of when to use HDR is standing inside your house on a bright day, take a picture through a window to the brightly lit outdoors.
Now try to do that and get whatever is out side your window to show up at the same time as the tables and chairs or whatever inside your room do.
This is pretty much impossible witha single shot. You either get the outdoors showing up, but the room completely blacked out, or you get the room to show up but the window is just a big white square that you can't see anythingi in.
Not the best result, but this gives you the idea of this in action
http://www.flickr.com/photos/jonatha...ol-truetonehdr
Here is another shot that does HDR well
http://www.flickr.com/photos/fersy/2...ol-truetonehdr
With a normal single shot, both of those would have had very dark areas or blown out white areas. It's tempting to say they don't look special at all, taht's just what you would normally see... but go try to shoot similar shots with a single from on a regular camera and you will start to understand what HDR is all about.
However some like the color popping and think that is what HDR means and thus strive for crazy colors and angry clouds. I personally say it's up to you. But hopefully here you will understand what HDR is about at least.
Oh and be careful messing with aperature to get HDR.... that is NOT A good idea. Changing aperature changes focal range and DOF. Getting 3 shots with different focal range and DOF means they won't look the same and when you blend them you will get weird blurines and incorrect image data. You wnat to LOCK y our aperature and change exposure to get your multiple exposures, not the other way around. You need multiple shots that focus the same, but have different brightness ranges.
What you want is called exposure bracketing. It changes the EV compensation automatically and snaps shots at multipel exposures for you. If you are on a tripod this eliminates the possiblity of movement between shots so your result will line up right. Be aware that often EV bracketing will be done by the camrea by altering the aperature. So put yoru camera in aperature priority mode, lock your aperature, and then snap away.
Also images do not have to be RAW, the reason some people like RAW is that a cameras sensor often can pick up 12 bits of data and dump it all into a raw file, then chop and compress the range to fit into an 8bit jpeg. Sticking with raw means that 3 exposures could cover up to 36 bits of range while 3 8 bit jpgs could only cover 24 bits... (you always overlap exposures so you won't ever get those numbers, but the point is).
Bear in mind many cheaper cameras these days (I am saying sub $500) do nto have sensors capable of much more dynamic range than a 8 bit jpg can hold... so going RAW on cameras witn sensors that don't really capture more range than the jpg can isn't nearly as beneficial.
05-10-2008, 08:24 PM
#45
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Well, my camera is around 200-250, so I can't do raw and stuff.
But........is it possible at all, assuming I could get a program that does HDR, to simply take pictures at different exposures and get a similar, HDR-ish effect?
But........is it possible at all, assuming I could get a program that does HDR, to simply take pictures at different exposures and get a similar, HDR-ish effect?
05-10-2008, 08:33 PM
#46
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Originally Posted by SCIONshane
Well, my camera is around 200-250, so I can't do raw and stuff.
But........is it possible at all, assuming I could get a program that does HDR, to simply take pictures at different exposures and get a similar, HDR-ish effect?
But........is it possible at all, assuming I could get a program that does HDR, to simply take pictures at different exposures and get a similar, HDR-ish effect?
05-10-2008, 08:41 PM
#47
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BTW depending on what camera it is you may be able to mess with the firmware to get raw shots, if you have a canon look at CHDK and see if it supports your model. I wouldn't worry too much about it though... JPGs will do fine to start.
The problem with no built in bracketing is that when you change your exposure settings you will move the camera around and result in pictures that aren't exactly the same. When you stack them and process them HDR you will have to do some tweaking to get a good result.
Give it a try and see how things turn out though...
Oh and one thing I forgot to mention, HDR and car shots are tricky because one of the effects of HDR is high local contrast... what that means is that those reflections in your body will likely be enhanced. Sometimes this could be good, but often it results in a busy look that messes with the lines on your car.
A polarizer can help with this.
The problem with no built in bracketing is that when you change your exposure settings you will move the camera around and result in pictures that aren't exactly the same. When you stack them and process them HDR you will have to do some tweaking to get a good result.
Give it a try and see how things turn out though...
Oh and one thing I forgot to mention, HDR and car shots are tricky because one of the effects of HDR is high local contrast... what that means is that those reflections in your body will likely be enhanced. Sometimes this could be good, but often it results in a busy look that messes with the lines on your car.
A polarizer can help with this.
05-10-2008, 09:47 PM
#48
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Excelent explination. but fro all the pictures i have taken and the research I have done on HDR, aperture bracketing is 95% of the time, the reccomended way to do it. The AEB settings is how it is done on Canons atleast. Just go to the AEB set +/- 1-2 steps and shoot from there. If I want more than three pictures, I adjust the exposure a tad and repeat.
So I can just shoot adjust exposure shoot again and continue? I dont need to bracket it?
So I can just shoot adjust exposure shoot again and continue? I dont need to bracket it?
05-11-2008, 12:22 AM
#50
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Originally Posted by Nick06tC
Excelent explination. but fro all the pictures i have taken and the research I have done on HDR, aperture bracketing is 95% of the time, the reccomended way to do it. The AEB settings is how it is done on Canons atleast. Just go to the AEB set +/- 1-2 steps and shoot from there. If I want more than three pictures, I adjust the exposure a tad and repeat.
So I can just shoot adjust exposure shoot again and continue? I dont need to bracket it?
So I can just shoot adjust exposure shoot again and continue? I dont need to bracket it?
Think about it... do you really want to mess with DOF when trying to snap multiple shots that you want to stack and combine? A tree will be blurry in one picture that won't be in another and what not...
I agree, AEB is the way to go, but I always make sure my camera is in Aperature Priority mode so I can set it to what I feel is appropriate and then shutter speed controls the exposure. Remember like I said, letting a camera control EV compensation on it's own can result in any combination of aperature and shutter speed fiddling (maybe even ISO).
If aperature has been working for you, ok... can't argue with results, but understanding how tinkering with aperature works I can't really see how it does unless all you shoot is landscapes.
BTW just to make sure there is no confusion, AEB stands for Auto Exposure Bracketing... it just controls how many stops you bracket, not how... maybe you thought AEB stands for Aperature Exposre Bracketing? The only time AEB will result in aperature bracketing is in Shutter Speed priority where the camera can only alter aperature to change exposure.
And the A720 is no slouch of a camera. It's not up with DSLRs by anymeans but from what I recall (never owned one but read up on them) it was a pretty decent performer across the board. I would think with a tripod (and I think you can slap CHDK on that) you would be fine to start snapping HDR with the A720.
Another note, for canon owners, if you can get CHDK running there are scripts made specifically for HDR. I think AllBests build has an intervelometer that can automate some of the process and if not there are some other things in the works. I haven't tested them much as when I started they were all pretty weak and I just do things manually:
Put camera in Aperature Priority
Set AEB Brackeing to +/- 2 stops (I think 2 is the max... I haven't changed it in so long I don't remember)
Setup the tripod
Put camera in 2 second delay (you want to do this so your finger doesn't shake the camera releasing the shutter. 2 seconds sitting on the tripod will let the camera be completely still for all your shots).
Shoot away.
If the scene has a LOT of range, I will set EV compensation to -2, shoot 3 shots, then go +2 and shoot 3 shots. This gives me 5 shots instead of 3 which has worked out well for me in the past. Problem is it involves touching the camera between the 2 sets of shots so it's risky...
05-11-2008, 04:07 AM
#51
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What you say deffinetly makes sense. And you are probably right that I was confusing AEB. I thought the A was Aperture.
I run a Canon Xt. I shoot HDR on the Adep setting.
I willd effinetly try out the way you are talking by adjusting shutter speed instead. Hope I dont move the camera when spinning the wheel.
I run a Canon Xt. I shoot HDR on the Adep setting.
I willd effinetly try out the way you are talking by adjusting shutter speed instead. Hope I dont move the camera when spinning the wheel.
05-11-2008, 04:23 AM
#52
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Just to be clear, if you are shooting a 3 shot bracket, don't touch the wheel, just set AEB and put the camera in aperature priority mode (not sure what the equivalent is or if there is one on the XT). If you force aperature, the camera has no choice but to adjust shutter speed to get the different EVs. This does not require spinning the wheel at all for a standard 3 shot bracket.
If you mean for the 5 shot bracket, yes you will have to touch the dial.
From what I understand about ADEP I would stay away from it as it is allowing the camera to chose Aperature. I prefer to lock it using Av mode.
If you have been using ADEP and AEB you are basically doing the method I am talking about. I would just switch to using Av and AEB. This will let you set an aperature and it will stick, no chance the camera will mess with it.
BTW Despite it's price range I think the sensor in the XT is good enough that it's wroth shooting RAW... might get you a little better results and gives the added benefit of being able to develop it how you like after the fact if you should feel like it...
If you mean for the 5 shot bracket, yes you will have to touch the dial.
From what I understand about ADEP I would stay away from it as it is allowing the camera to chose Aperature. I prefer to lock it using Av mode.
If you have been using ADEP and AEB you are basically doing the method I am talking about. I would just switch to using Av and AEB. This will let you set an aperature and it will stick, no chance the camera will mess with it.
BTW Despite it's price range I think the sensor in the XT is good enough that it's wroth shooting RAW... might get you a little better results and gives the added benefit of being able to develop it how you like after the fact if you should feel like it...
05-11-2008, 05:03 AM
#54
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PS or Gimp are the two most popular ways to do it manually. And manually is pretty much the best way as it gives you full control over what is selected and what is tone mapped. Using the automatic programs often results in odd colors, light blooms and other odities... automatic is never as good as manual 
That said I still use the automatic programs most of the time, the manual method is quite time consuming and I like to play around a lot, so a quick program is just convenient.
But to start I recomend photomatix and dynamic photo hdr. Start with them, and then when you start to get a feel for HDR, try the PS or Gimp methods for control. Just like cameras, start with a simple P&S and when you outgrow the auto settings, start doing manual
That said I still use the automatic programs most of the time, the manual method is quite time consuming and I like to play around a lot, so a quick program is just convenient.
But to start I recomend photomatix and dynamic photo hdr. Start with them, and then when you start to get a feel for HDR, try the PS or Gimp methods for control. Just like cameras, start with a simple P&S and when you outgrow the auto settings, start doing manual
05-11-2008, 05:08 AM
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I will switch over to AV. and try shooting in RAW. See what happens. I might mess around with some indoor shots, to outdoor and see what happens.
Thanks for the tips!!!
Thanks for the tips!!!
05-11-2008, 05:14 AM
#56
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Always glad to share what knowledge I can! Lord knows it was an uphill battle sorting out the details back when I was first picking up HDR... Some of the threads I recall put "VVTI vs VTEC" to shame!
Something to consider, I think Photomatix handles RAW images natively... not sure but worth checking out too.
I only have an S3 so I am already jealous of you SLR guys
Something to consider, I think Photomatix handles RAW images natively... not sure but worth checking out too.
I only have an S3 so I am already jealous of you SLR guys
05-11-2008, 08:53 AM
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Originally Posted by CarbonXe
Watching, gonna have to try this out with my D40. What programs do you guys use to combine the images? PS?
It should be a freeware program to download. Does very well. PS CS3 can do it. but its very ahrd to use. Deffinetly not as user friendly as photomatix.
05-11-2008, 09:15 AM
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Originally Posted by Nick06tC
That is deffinetly what HDR is. But the pictures dont have to be RAW. They can be done in normal JPG format. But RAW is much much better. And its not exposure timing you adjust. You adjust the range of the aperture value. usually plus 1-2 steps in either direction from normal.
CS 3 for me seems to work the best since the pictures line up correctly, even if all your pictures are slightly off.
05-11-2008, 06:35 PM
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Originally Posted by Nick06tC
Originally Posted by CarbonXe
Watching, gonna have to try this out with my D40. What programs do you guys use to combine the images? PS?
It should be a freeware program to download. Does very well. PS CS3 can do it. but its very ahrd to use. Deffinetly not as user friendly as photomatix.
So what's the easiest way to just take a bunch of shots? Should I just take a bunch of pictures with different exposure settings and leaving aperture and shutter speed the same?
05-11-2008, 06:41 PM
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Sadly the D40 doesn't have AEB so you will have to figure out how to manually bracket.
Here is how to pull it off with a D40... sadly the lack of bracketing means you run the risk of moving the camera and not having perfectly lined up shots. This can be compensated for during the HDR process if the movement is slight.
http://dptnt.com/2007/10/hdr-photogr...ing-nikon-d40/
Here is how to pull it off with a D40... sadly the lack of bracketing means you run the risk of moving the camera and not having perfectly lined up shots. This can be compensated for during the HDR process if the movement is slight.
http://dptnt.com/2007/10/hdr-photogr...ing-nikon-d40/