about HDR


denniskee

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#1
Reading Complete Guide to HDR Digital Photography by Ferrell Mccollough, just something to share here :

1) Adjustments to be avoided before HDRing :
Tone (you can adjust them provided you adjust the same amount to all the photos).
Brightness
Exposure
Saturation
Contrast
Shadows
Curves
Sharpening


2) Allowable Adjustments without negative effect on the final output :
White Balance
Chromatic Aberration
Color Noise Reduction
Lens Distortion
B/W Conversion
Crop
Resize


3) Contrary to common thought that one can use a single RAW file to do HDR by adjusting the exposure values, you cant. Reason is the single exposure has a fixed Dynamic Range (DR), changing the exposure value in post-processing create noise-free shadows or recover lost highlights. The image is bound by the limited DR of the sensor and the only way to extend the range is through multiple images at the different shutter speed.


4) Use Manual Mode, Aperture Priority Mode together with Auto Exposure Bracketing (AEB) together with Continuous Shooting Mode or Exposure Compensation (EC) if your camera doesnt have AEB or Manual Mode.


5) Dont use Shutter Priority as it will change the Aperture Value, thus changing the Depth of Field (DOF). Dont use flash


6) Shoot with a fixed White Balance, lowest ISO for noise-free pictures & focus on the same distant (else DOF may be affected).


7) Use Tripod where possible to minimize misalignment. Else brace the camera to a structure and fix 1 or more reference point/s.
 

eyes

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#2
The following broke every single rule mentioned above. :bsmilie:


This single snap shot was taken by my buddy in 5 seconds in auto mode while returning to the car after grabbing early dinner.







After 1 exposure HDR processing:



Canon 350D, (EF-S 18-55mm f/3.5-5.6), 21mm, f/9, 1/500s, ISO800.


.
 

night86mare

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#3
that scene doesn't need HDR in the first place... i can do whatever is done with the tone mapping with simple photoshop cs2. that includes oversaturating the cyan channel on the left side of the picture.
 

wildcat

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#4
that scene doesn't need HDR in the first place... i can do whatever is done with the tone mapping with simple photoshop cs2. that includes oversaturating the cyan channel on the left side of the picture.
Hmm... need to go find out more about what tone mapping is :think:

I would have just used Curve and/or contrast in PS.

I also don't know how some people can do HDR with single shot :dunno: I guess can still extract extra info from RAW format, but I prefer bracketed shots.
 

jopel

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#5
that scene doesn't need HDR in the first place... i can do whatever is done with the tone mapping with simple photoshop cs2. that includes oversaturating the cyan channel on the left side of the picture.
:bsmilie::bsmilie::bsmilie: I will use curve, selective colour, Saturation and USM
 

mhmusic

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#6
Thanks a lot for your sharing. These points are such very useful information :thumbsup:
 

2evans

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#7
I also don't know how some people can do HDR with single shot :dunno: I guess can still extract extra info from RAW format, but I prefer bracketed shots.
If you have a moving object in your photo that you are trying to retain, would using 1 raw file be better to manipulate?
 

wildcat

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#8
If you have a moving object in your photo that you are trying to retain, would using 1 raw file be better to manipulate?
Maybe. I feel each tool has it's place. If there are a lot of moving objects in the photo, would HDR be the best tool to use?

I may use exposure blending instead.

At the moment, I am trying to expand the list of tools available to me as a photographer so that I have a choice and can make better informed decisions when I need to take the shot. As night86mare mentioned above, a shot that don't need to be HDR, then don't HDR just for it's sake; but the person may not know any other option than to just "HDR" everything.
 

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2evans

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#9
Maybe. I feel each tool has it's place. If there are a lot of moving objects in the photo, would HDR be the best tool to use?

I may use exposure blending instead.

At the moment, I am trying to expand the list of tools available to me as a photographer so that I have a choice and can make better informed decisions when I need to take the shot. As night86mare mentioned above, a shot that don't need to be HDR, then don't HDR just for it's sake; but the person may not know any other option than to just "HDR" everything.
Yes, you're correct in that not everything needs to be HDR. :)
Having more tools and methods in your bag of tricks is certainly better than always trying to process a photo using one technique/method. The example above was my newbie attempt to present a scenario where one might need to use a single image, but perhaps one could use exposure blending if the image "allows" for it. It's up to the user to decide what method or results they want to achieve and the ease by which they can attain it... etc. :)
 

eyes

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#10
The above test pic took 5 minutes to run through. How long will alternative techniques take? Can they produce the same quality? What people choose to use depends on their needs, there's no right or wrong answer.
 

night86mare

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#11
The above test pic took 5 minutes to run through. How long will alternative techniques take? Can they produce the same quality? What people choose to use depends on their needs, there's no right or wrong answer.
i will take 2 minutes and create a much better photograph.

the quality very good meh, cyan channel is glowing in the dark......... i tell you, photomatix is a crap program. i only use it as a last resort.
 

denniskee

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#13
If you have a moving object in your photo that you are trying to retain, would using 1 raw file be better to manipulate?
In this book, there are "guest" photographer penning some of their thoughts. One such Domingo Leiva mentioned :

"For scenes with movement, I shoot a single RAW file and tone map it to create an HDR photo."

Which Ferrell Mccollough did mentioned :

" One can tone map a single 8bit or 16 bit. It is a popular method to enhance shadow details in low DR images.

But if the original image has alot of noise, tone mapping will enhance the noise."


I guess there are 3 things to take note of here.

1) Single tone mapping for low DR is possible. Depending what individual's own definition of what is HDR, skipping the previous step of combining several photos into one, is this still a HDR?

2) Single tone mapping can be replace by other processing method to level up the contrast, colors and details.

3) Movements will create ghosting with HDR (combining several photos), under to avoid this problem, there is a saying "No fish prawn also good."
 

ovaltinemilo

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#14
DR is innate in the sensor. Using one raw file can only give the limited DR that the sensor can produce. As such, HDR using 1 raw file won't produce DR as good as produced by 3 or 5 shots. Infact, this method only tries to maximize the DR of the camera, not producing HDR as high as produced by 3,5 or more shots. And yes, 1 raw shot works for moving objects. 2 or more shots on moving objects = headache during merging:bsmilie:
 

night86mare

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#15
You got an example?
i do tonight just for you, with timer for 2 minutes. ;)

sometimes, we are so awed when we have little knowledge. when you have the knowledge, a lot of things become less awesome.

especially for 1 shot HDRs, it is nothing more than a gimmicky effect, can easily create actions to output such with the proper exposure in that sort of lighting.
 

denniskee

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#16
DR is innate in the sensor. Using one raw file can only give the limited DR that the sensor can produce. As such, HDR using 1 raw file won't produce DR as good as produced by 3 or 5 shots. Infact, this method only tries to maximize the DR of the camera, not producing HDR as high as produced by 3,5 or more shots. And yes, 1 raw shot works for moving objects. 2 or more shots on moving objects = headache during merging:bsmilie:
u r Domingo Leiva??!!:bigeyes::bigeyes::bigeyes:
 

denniskee

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#17
I guess low DR scene means the sensor DR is more than the scene, so there wont be problem to extract more info out of the shot.
 

theRBK

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#18
tone-mapping one image is just that, tone-mapping one image... it makes adjustments within the dynamic range captured within that one image, enhancing (and I use that term very losely in this context ;p) the visible tonal representation of the image... but the dynamic range of that image is still within what was originally there in that one image, typically between 6 to 10 stops in RAW files and 16-bit tifs, less for jpgs...

but in the case of HDR, the dynamic range usually considered is typically 14 stops and above... with the current state of sensor technology, commercially available digital cameras are still not able to achieve such wide dynamic range captures within a single image, thus the need to merge different exposures to create HDR images...

so yes, one can tone-map a single image, but that does not mean that you have created a HDR image...
 

hotwork77

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#20
i will take 2 minutes and create a much better photograph.

the quality very good meh, cyan channel is glowing in the dark......... i tell you, photomatix is a crap program. i only use it as a last resort.
You got an example?
You never see night86mare samples on HDR meh? It's one of the best I have seen so far. The get the goat to talk is a miracle by itself. Keke...:bsmilie:
 

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