Extend dynamic range - quick & easy

[Gordon W]

I was inspired by another thread to put together a pBase gallery showing my quick & easy technique for extending dynamic range by using two images from a bracket (since I don't have RAW capability yet)...

http://www.pbase.com/merriwolf/extend_dynamic_range

...rather than post all the images here, for the sake of those on dialup. But I will show before and after here.

Before



After



You can see in the second image there's quite a bit more detail in the sky without the foreground being significantly effected (other than by my typical post-processing adjustments like levels, color balance, etc.)

Basically though, the technique is nothing more than...

1. Shoot brackets of a scene.

2. Take the light and dark images of the three images.

3. On the darker image, command-click (on a Mac, or Alt-click in Windows) on the RGB composite channel in Photoshop's Channels palette. This automatically selects the lighter tones in the image.
4. Copy

5. Paste into into the lighter image which will automatically put the highlight data you just copied into a new layer.

6. And that should just about do it except for making whatever adjustments you like to optimize the image.

And for those who love to get in there and play in Photoshop, this also affords the opportunity for a lot of control.

BTW, Charles Lloyd gets credit for showing me the Command-click on the RGB channel trick.



http://www.pbase.com/merriwolf/

 

[JamesMontgomery]

of trying to extend dynamic range using the theory you describe, but having to dodge, burn, and do various contortions to the paper and the negative!

Haven't things become much easier?

Hooray for advancements!

-James

 

[Jersey Boy]

Gordon W ,

I do not have PS but just by inspection, it looks like noise is lowered in some areas.

 

[Olga Johnson]

Great thread you started, Gordon. I will try it your way (which is manual to me (LOL) and see how it goes. I just have to learn how this stuff works.

Olga

I was inspired by another thread to put together a pBase gallery
showing my quick & easy technique for extending dynamic range by
using two images from a bracket (since I don't have RAW capability
yet)...

http://www.pbase.com/merriwolf/extend_dynamic_range
...rather than post all the images here, for the sake of those on
dialup. But I will show before and after here.

Before



After



You can see in the second image there's quite a bit more detail in
the sky without the foreground being significantly effected (other
than by my typical post-processing adjustments like levels, color
balance, etc.)

Basically though, the technique is nothing more than...

1. Shoot brackets of a scene.

2. Take the light and dark images of the three images.
3. On the darker image, command-click (on a Mac, or Alt-click in
Windows) on the RGB composite channel in Photoshop's Channels
palette. This automatically selects the lighter tones in the image.
4. Copy
5. Paste into into the lighter image which will automatically put
the highlight data you just copied into a new layer.

6. And that should just about do it except for making whatever
adjustments you like to optimize the image.

And for those who love to get in there and play in Photoshop, this
also affords the opportunity for a lot of control.

BTW, Charles Lloyd gets credit for showing me the Command-click on
the RGB channel trick.



http://www.pbase.com/merriwolf/

 

[Gordon W]

I do not have PS but just by inspection, it looks like noise is
lowered in some areas.

Hmm...Interesting thought and I hadn't ever considered that in regard to this technique, and it is a form of stacking, but several things at work here.

First, it is very unlikely there will be noticeable noise in the low res files I posted. 5MP images even shot at high ISO and have noise the size of sand look clean when reduced to 480 pixels wide.

Secondly, the base image is the overexposed one, which by the nature of image noise will inherently have fairly low noise to begin with and I can see almost no noise in it even viewed at 100%.

Then you're taking the highlights and lighter tones from the underexposed shot which by the nature of image noise will inherently have fairly high noise in comparison, although even in the highlights and lighter tones of the underexposed shot the noise levels are not high, only in the darker tones and shadows which aren't used.

So you then combine two images that are already pretty noise free and I can see almost no noise in anything in the full resolution file.

Thanks for asking though. Made me think. ;-)



http://www.pbase.com/merriwolf/

 

[David_S85]

Thanks Gordon for posting this subject again. Its just so incredibly easy, once you have a couple shots from a tripod (and best using the a remote for the camera to minimize shake even more).

Here's how I do it quick and dirty in PSP7. PSP8 works similar. And it cleans up noise as well.

1. Open both images.
2. Duplicate them (Shift + D) to avoid copying over them.
3. Close originals to preserve them.
4. DO NOT adjust Levels or Curves at this point, we'll do that later.
5. Copy/Paste darker image as a layer over the lighter image.
6. Make top darker (top) image the active layer.

7. Select from top menu bar - Mask > New > "From Image" > choose "This Window," "Source Luminace" and keep "Invert mask data" unchecked, then click "OK."
8. Keep blending mode at "Normal," and blend to taste.
9. Merge (flatten) both layers.
10. At this point, you're basically done.

Additional steps to finish up:

You might want to adjust your image Levels, Curves or Contrast, resize and Unsharp Mask as you normally would.

notes:

If you have used a sturdy tripod, and camera shake has not been a problem, then your two images are probably aligned to the pixel level. To make sure, following step 6 above, temporarily change your blending mode on the top layer to "Difference," zoom in closer, and use the Mover tool to fine align the images to match. Change blending mode back to "Normal" when your images line up.

Layer Mask Method for PSP7 adapted from article at:
http://www.luminous-landscape.com/tutorials/digital-blending.shtml
and from George DeWolfe of CameraArt's magazine.

• David

 

[Gordon W]

Thanks, Olga. I'll be interested in seeing what you come up with. The dynamic range of these shots weren't as extreme as some I have but these were handy.

Olga

I was inspired by another thread to put together a pBase gallery
showing my quick & easy technique for extending dynamic range by
using two images from a bracket (since I don't have RAW capability
yet)...

http://www.pbase.com/merriwolf/extend_dynamic_range
...rather than post all the images here, for the sake of those on
dialup. But I will show before and after here.

Before



After



You can see in the second image there's quite a bit more detail in
the sky without the foreground being significantly effected (other
than by my typical post-processing adjustments like levels, color
balance, etc.)

Basically though, the technique is nothing more than...

1. Shoot brackets of a scene.

2. Take the light and dark images of the three images.
3. On the darker image, command-click (on a Mac, or Alt-click in
Windows) on the RGB composite channel in Photoshop's Channels
palette. This automatically selects the lighter tones in the image.
4. Copy
5. Paste into into the lighter image which will automatically put
the highlight data you just copied into a new layer.

6. And that should just about do it except for making whatever
adjustments you like to optimize the image.

And for those who love to get in there and play in Photoshop, this
also affords the opportunity for a lot of control.

BTW, Charles Lloyd gets credit for showing me the Command-click on
the RGB channel trick.

--



http://www.pbase.com/merriwolf/

 

[Jamie154594]

Thanks Gordon for this thread. Like I said before, you need to post more!

I changed the subject line so I can find this post again in the future.. because to me this is a simplified stacking technique.

I have many muscle car pictures I need to try this one on!

Jamie

 

[Gordon W]

Thanks, David. I was wondering if there was a way to do this in PSP.

Thanks Gordon for posting this subject again. Its just so
incredibly easy, once you have a couple shots from a tripod (and
best using the a remote for the camera to minimize shake even more).

Here's how I do it quick and dirty in PSP7. PSP8 works similar. And
it cleans up noise as well.

1. Open both images.
2. Duplicate them (Shift + D) to avoid copying over them.
3. Close originals to preserve them.
4. DO NOT adjust Levels or Curves at this point, we'll do that later.
5. Copy/Paste darker image as a layer over the lighter image.
6. Make top darker (top) image the active layer.
7. Select from top menu bar - Mask > New > "From Image" > choose
"This Window," "Source Luminace" and keep "Invert mask data"
unchecked, then click "OK."
8. Keep blending mode at "Normal," and blend to taste.
9. Merge (flatten) both layers.
10. At this point, you're basically done.

Additional steps to finish up:
You might want to adjust your image Levels, Curves or Contrast,
resize and Unsharp Mask as you normally would.

notes:
If you have used a sturdy tripod, and camera shake has not been a
problem, then your two images are probably aligned to the pixel
level. To make sure, following step 6 above, temporarily change
your blending mode on the top layer to "Difference," zoom in
closer, and use the Mover tool to fine align the images to match.
Change blending mode back to "Normal" when your images line up.

Layer Mask Method for PSP7 adapted from article at:
http://www.luminous-landscape.com/tutorials/digital-blending.shtml
and from George DeWolfe of CameraArt's magazine.

• David

--



http://www.pbase.com/merriwolf/

 

[Jerry Stevens]

Thanks, Gordon. Definitely part of what makes STF working through! Very helpful and simple to implement.

Jerry
--
Gerald L. Stevens

 

[Gordon W]

I changed the subject line so I can find this post again in the
future.. because to me this is a simplified stacking technique.

True, it is a form of stacking, but a more selective form in that with normal stacking all the tones are averaged together, where in this case only the lighter tones are average leaving the darker tones and shadows essentially unchanged.

The effect can also be intensified somewhat by changing the blending mode from Normal to Multiply, but I seldom need to do this.

I have many muscle car pictures I need to try this one on!

I'm quite interested in seeing how they come out.



http://www.pbase.com/merriwolf/

 

[cspringer]

open Levels or Curves and click Option

http://forums.dpreview.com/forums/read.asp?forum=1006&message=7451121

Thanks, Gordon. Definitely part of what makes STF working through!
Very helpful and simple to implement.

Jerry
--
Gerald L. Stevens

 

[Lynn Towns]

Hi David,

I tried your method in PSP8 because there must be several ways to blend images. Either I did something wrong with your method, or else this method works better. Please try it out and let me know what you think. I'm always looking for better methods, so if I made a mistake with your method, I would like to know.

Blending Two Images that have Different Exposures (must be shot using a tripod):

1. Copy the light image, and paste it onto the dark image as a new layer.

2. Choose Raster 1 (light image) and duplicate it.

3. Choose “Copy of Raster 1” (the duplicate layer) and adjust the saturation to -100.

4. With “Copy of Raster 1” still active, adjust the brightness/contrast. Start with brightness=-10, and contrast=60. The goal is to have an all white-background (often sky at the top of the photo), with an all-black foreground (often ground at the bottom of the photo).

5. Now, choose “Raster 1” (light image) again, and click Layers> New Mask Layer> From Image. The "Source window" should be the dark image, and for "Create mask from", choose "Source luminance". Check the "Invert mask data" box, and click "OK".

6. Choose the “Copy of Raster 1”, and click on the visibility toggle (red X). The image should now be a blended version of the two images.

7. Flatten the image, and you’re done blending.

Lynn

 

[Dan Mayer]

tagging this thread

 

[Ann McRae]

Gordon

Thank you for all of these posts, I have read them and bookmarked them. They are very informative and useful.

I am trying to work out which city this is - and I am thinking Ottawa or Quebec City. Am I way off?

ann
--
Canadian Ann
Under construction:
http://canadian-ann.smugmug.com
http://www.pbase.com/canadian_ann
http://www.cs.duke.edu/~parr/photography/faq.html
I like to call it menopause mauve!

 

[Gordon W]

Gordon
Thank you for all of these posts, I have read them and bookmarked
them. They are very informative and useful.
I am trying to work out which city this is - and I am thinking
Ottawa or Quebec City. Am I way off?

Hi Ann,

Nope, bang on. Sunset in Ottawa, from the top of the Peace Tower. That's the Ottawa River running up the right side of picture and we're currently in the midst of 'Winterlude'. ;-)

http://www.pbase.com/merriwolf/winterludeottawa



http://www.pbase.com/merriwolf/

 

[Evil Eggplant]

This is nice and simple. The results look good. I'm looking forward to trying this. Thanks!

--
rich
'beware the eggplant'
c-7oo, d-51O, DSC-F7O7, 3OOD
'it's not having what you want, it's wanting what you got'
http://www.iceninephotography.com

 

[Gordon W]

open Levels or Curves and click Option
http://forums.dpreview.com/forums/read.asp?forum=1006&message=7451121

Thanks for pointing this out, cs. While it's not extending dynamic range by restoring detail that was lost due to clipping, it does extend the range of the data that's in the file and is an extremely useful tip for quick and easy color and contrast correction.

This page gives all the details...

http://www.informit.com/isapi/product_id~%7BDCAB02EF-ECAE-4DB7-9833-5231BCBA2384%7D/element_id~%7B81E3CD5A-762E-4E8F-9AC9-4A0AC5D71864%7D/st~%7B30DCE543-8F6C-4B3A-A0F2-F9739BA4F054%7D/content/articlex.asp

Using this in a Levels or Curves Adjustment Layer also allows the adjustments to be made without changing the original image layer itself, so further changes can be made later to these adjustments if needed without having lost any of the original image's data (I do as much as I can using Adjustment Layers for this reason).

I'm not a fan of the 'Auto' commands because their default settings create clipping, but this allows some parameters to be set for them which is extremely useful as well.

And...since this is redistributing tones in an image, it will work most effectively on a 16-bit image, as in the output file from Photoshop CS's RAW plugin.

And finally...this feature was introduced in Photoshop 7, so you won't find it in earlier versions.



http://www.pbase.com/merriwolf/

 

[David_S85]

Lynn Towns wrote:
....

Hi David,

 

[Gordon W]

Like I said before, you need to post more!

...have you checked out dpreview's Retouching forum, Jamie?

http://forums.dpreview.com/forums/forum.asp?forum=1006

There is a wealth of information there that is sure to feed your newfound passion for post-processing. ;-)

There are people there who know far more than I do about these things. I'm one of those folks who learns to do what needs to be done to achieve something and then doesn't pursue it further, having reached my comfort level, whereas the Retouching gurus live and breath this stuff. ;-)

STF is my dpreview home, but the Retouching forum is my home away from home (although I have seldom ever posted there for fear of making a fool of myself ;-).



http://www.pbase.com/merriwolf/