G3 exposure latitude: solutions and examples

Chuck Martin said:

Hello all,

Some recent posts prompted me to wrap up my exposure latitude
project with the G3, and I am presenting the results here. The
first steps were to define the built-in exposure response of the
G3, and a desired modified response providing enhanced exposure
latitude. These are portrayed at the link below as curves created
by plotting the Photoshop RGB value as a function of exposure. The
response curves were then used to create Photoshop Curves that
could be used to convert a deliberately underexposed image into a
properly exposed one having enhanced exposure latitude. The
Photoshop Curves definitions for various levels of underexposure
are shown in a table at the same link.

Use of the Photoshop Curves definitions is shown in the first five
photos. Photo #1 is of a contrasty scene properly exposed for the
shaded portions, but having badly blown highlights and a washed out
sky. Photos #2 and #3 are of the same scene, but with one and two
stops less exposure respectively. Photo #4 is Photo #2 with the
appropriate Photoshop Curves definition applied. Midtones have the
same intensity as in Photo #1, but the highlights now show
significant detail. Increased noise and loss of detail in the
shadows is minimal. Photo #5 is Photo #3 with the Photoshop Curves
definition for two stops underexposure applied. Again, midtones
have the same intensity as in Photo #1, but now highlights show
even more improvement than in Photo #4. Unfortunately, noise and
loss of detail in the shadows are becoming quite noticeable.

Wouldn't it be nice if detail could be added to the highlights
without adverse effects in the shadows? Well for static subjects
it can. Photos #6 and #7 show the results of merging light and
dark photos using the following procedure in Photoshop:

For dark photo (#2 or #3)
1. Correct with appropriate Curves definition
2. Lighten midtones and shadows in Levels by shifting middle
slider left to give a reading of 1.15 to 1.30
3. Select All
4. Copy

For light photo (#1)
1. Paste
2. Change layer blending from Normal to Darken
3. Flatten layers

That's it. The merged photo now shows shadow and midtone detail
from the noise-free light photo, and highlight detail from the dark
photo. The trick is in using the Darken blending mode, and in
making certain that the shadows and midtones in the corrected dark
photo are lighter than in the light photo.

I know this explanation is sketchy, but I don't want to waste my
time unless interest is shown.

Enjoy,

Chuck

http://www.pbase.com/chuck_martin/latitude

Click to expand...

Chuck Martin said:

Hello all,

Some recent posts prompted me to wrap up my exposure latitude
project with the G3, and I am presenting the results here. The
first steps were to define the built-in exposure response of the
G3, and a desired modified response providing enhanced exposure
latitude. These are portrayed at the link below as curves created
by plotting the Photoshop RGB value as a function of exposure. The
response curves were then used to create Photoshop Curves that
could be used to convert a deliberately underexposed image into a
properly exposed one having enhanced exposure latitude. The
Photoshop Curves definitions for various levels of underexposure
are shown in a table at the same link.

Use of the Photoshop Curves definitions is shown in the first five
photos. Photo #1 is of a contrasty scene properly exposed for the
shaded portions, but having badly blown highlights and a washed out
sky. Photos #2 and #3 are of the same scene, but with one and two
stops less exposure respectively. Photo #4 is Photo #2 with the
appropriate Photoshop Curves definition applied. Midtones have the
same intensity as in Photo #1, but the highlights now show
significant detail. Increased noise and loss of detail in the
shadows is minimal. Photo #5 is Photo #3 with the Photoshop Curves
definition for two stops underexposure applied. Again, midtones
have the same intensity as in Photo #1, but now highlights show
even more improvement than in Photo #4. Unfortunately, noise and
loss of detail in the shadows are becoming quite noticeable.

Wouldn't it be nice if detail could be added to the highlights
without adverse effects in the shadows? Well for static subjects
it can. Photos #6 and #7 show the results of merging light and
dark photos using the following procedure in Photoshop:

For dark photo (#2 or #3)
1. Correct with appropriate Curves definition
2. Lighten midtones and shadows in Levels by shifting middle
slider left to give a reading of 1.15 to 1.30
3. Select All
4. Copy

For light photo (#1)
1. Paste
2. Change layer blending from Normal to Darken
3. Flatten layers

That's it. The merged photo now shows shadow and midtone detail
from the noise-free light photo, and highlight detail from the dark
photo. The trick is in using the Darken blending mode, and in
making certain that the shadows and midtones in the corrected dark
photo are lighter than in the light photo.

I know this explanation is sketchy, but I don't want to waste my
time unless interest is shown.

Enjoy,

Chuck

http://www.pbase.com/chuck_martin/latitude

Click to expand...

• Would your conclusion be that by using blending we can extend the dynamic range of the G3 (and probably most CCD-based cameras) by 1 stop without too much effort and by 2 stops with a bit more work?
• Do you think attempting to go beyond 2 stops is worthwhile?
• Do you think that by stacking two under-exposed photos with the normally exposed one we would also get rid of much of the random noise?

Chuck Martin said:

Hello all,

Some recent posts prompted me to wrap up my exposure latitude
project with the G3, and I am presenting the results here. The
first steps were to define the built-in exposure response of the
G3, and a desired modified response providing enhanced exposure
latitude. These are portrayed at the link below as curves created
by plotting the Photoshop RGB value as a function of exposure. The
response curves were then used to create Photoshop Curves that
could be used to convert a deliberately underexposed image into a
properly exposed one having enhanced exposure latitude. The
Photoshop Curves definitions for various levels of underexposure
are shown in a table at the same link.

Use of the Photoshop Curves definitions is shown in the first five
photos. Photo #1 is of a contrasty scene properly exposed for the
shaded portions, but having badly blown highlights and a washed out
sky. Photos #2 and #3 are of the same scene, but with one and two
stops less exposure respectively. Photo #4 is Photo #2 with the
appropriate Photoshop Curves definition applied. Midtones have the
same intensity as in Photo #1, but the highlights now show
significant detail. Increased noise and loss of detail in the
shadows is minimal. Photo #5 is Photo #3 with the Photoshop Curves
definition for two stops underexposure applied. Again, midtones
have the same intensity as in Photo #1, but now highlights show
even more improvement than in Photo #4. Unfortunately, noise and
loss of detail in the shadows are becoming quite noticeable.

Wouldn't it be nice if detail could be added to the highlights
without adverse effects in the shadows? Well for static subjects
it can. Photos #6 and #7 show the results of merging light and
dark photos using the following procedure in Photoshop:

For dark photo (#2 or #3)
1. Correct with appropriate Curves definition
2. Lighten midtones and shadows in Levels by shifting middle
slider left to give a reading of 1.15 to 1.30
3. Select All
4. Copy

For light photo (#1)
1. Paste
2. Change layer blending from Normal to Darken
3. Flatten layers

That's it. The merged photo now shows shadow and midtone detail
from the noise-free light photo, and highlight detail from the dark
photo. The trick is in using the Darken blending mode, and in
making certain that the shadows and midtones in the corrected dark
photo are lighter than in the light photo.

I know this explanation is sketchy, but I don't want to waste my
time unless interest is shown.

Enjoy,

Chuck

http://www.pbase.com/chuck_martin/latitude

Click to expand...

Chuck Martin said:

Hello all,

Some recent posts prompted me to wrap up my exposure latitude
project with the G3, and I am presenting the results here. The
first steps were to define the built-in exposure response of the
G3, and a desired modified response providing enhanced exposure
latitude. These are portrayed at the link below as curves created
by plotting the Photoshop RGB value as a function of exposure. The
response curves were then used to create Photoshop Curves that
could be used to convert a deliberately underexposed image into a
properly exposed one having enhanced exposure latitude. The
Photoshop Curves definitions for various levels of underexposure
are shown in a table at the same link.

Use of the Photoshop Curves definitions is shown in the first five
photos. Photo #1 is of a contrasty scene properly exposed for the
shaded portions, but having badly blown highlights and a washed out
sky. Photos #2 and #3 are of the same scene, but with one and two
stops less exposure respectively. Photo #4 is Photo #2 with the
appropriate Photoshop Curves definition applied. Midtones have the
same intensity as in Photo #1, but the highlights now show
significant detail. Increased noise and loss of detail in the
shadows is minimal. Photo #5 is Photo #3 with the Photoshop Curves
definition for two stops underexposure applied. Again, midtones
have the same intensity as in Photo #1, but now highlights show
even more improvement than in Photo #4. Unfortunately, noise and
loss of detail in the shadows are becoming quite noticeable.

Wouldn't it be nice if detail could be added to the highlights
without adverse effects in the shadows? Well for static subjects
it can. Photos #6 and #7 show the results of merging light and
dark photos using the following procedure in Photoshop:

For dark photo (#2 or #3)
1. Correct with appropriate Curves definition
2. Lighten midtones and shadows in Levels by shifting middle
slider left to give a reading of 1.15 to 1.30
3. Select All
4. Copy

For light photo (#1)
1. Paste
2. Change layer blending from Normal to Darken
3. Flatten layers

That's it. The merged photo now shows shadow and midtone detail
from the noise-free light photo, and highlight detail from the dark
photo. The trick is in using the Darken blending mode, and in
making certain that the shadows and midtones in the corrected dark
photo are lighter than in the light photo.

I know this explanation is sketchy, but I don't want to waste my
time unless interest is shown.

Enjoy,

Chuck

http://www.pbase.com/chuck_martin/latitude

Click to expand...

astroman said:

Chuck,
Had a chance to examine your test further. Sorry, thought you were
attempting to show the true exposure latitude (dynamic range) of
the G3 without the layer blending effect. I know this is a cool
effect but its useful application is limited to specific photo
applications. Nevertheless a nice test and helpful to those
interested in the blend feature.

Click to expand...

Idiau Duvilaj said:

Interesting test. It raises a few questions in my mind:

• Would your conclusion be that by using blending we can extend the

dynamic range of the G3 (and probably most CCD-based cameras) by 1
stop without too much effort and by 2 stops with a bit more work?

• Do you think attempting to go beyond 2 stops is worthwhile?
• Do you think that by stacking two under-exposed photos with the

normally exposed one we would also get rid of much of the random
noise?

Click to expand...

Chuck Martin said:

Hello all,

Some recent posts prompted me to wrap up my exposure latitude
project with the G3, and I am presenting the results here. The
first steps were to define the built-in exposure response of the
G3, and a desired modified response providing enhanced exposure
latitude. These are portrayed at the link below as curves created
by plotting the Photoshop RGB value as a function of exposure. The
response curves were then used to create Photoshop Curves that
could be used to convert a deliberately underexposed image into a
properly exposed one having enhanced exposure latitude. The
Photoshop Curves definitions for various levels of underexposure
are shown in a table at the same link.

Use of the Photoshop Curves definitions is shown in the first five
photos. Photo #1 is of a contrasty scene properly exposed for the
shaded portions, but having badly blown highlights and a washed out
sky. Photos #2 and #3 are of the same scene, but with one and two
stops less exposure respectively. Photo #4 is Photo #2 with the
appropriate Photoshop Curves definition applied. Midtones have the
same intensity as in Photo #1, but the highlights now show
significant detail. Increased noise and loss of detail in the
shadows is minimal. Photo #5 is Photo #3 with the Photoshop Curves
definition for two stops underexposure applied. Again, midtones
have the same intensity as in Photo #1, but now highlights show
even more improvement than in Photo #4. Unfortunately, noise and
loss of detail in the shadows are becoming quite noticeable.

Wouldn't it be nice if detail could be added to the highlights
without adverse effects in the shadows? Well for static subjects
it can. Photos #6 and #7 show the results of merging light and
dark photos using the following procedure in Photoshop:

For dark photo (#2 or #3)
1. Correct with appropriate Curves definition
2. Lighten midtones and shadows in Levels by shifting middle
slider left to give a reading of 1.15 to 1.30
3. Select All
4. Copy

For light photo (#1)
1. Paste
2. Change layer blending from Normal to Darken
3. Flatten layers

That's it. The merged photo now shows shadow and midtone detail
from the noise-free light photo, and highlight detail from the dark
photo. The trick is in using the Darken blending mode, and in
making certain that the shadows and midtones in the corrected dark
photo are lighter than in the light photo.

I know this explanation is sketchy, but I don't want to waste my
time unless interest is shown.

Enjoy,

Chuck

http://www.pbase.com/chuck_martin/latitude

Click to expand...

Chuck Martin said:

Q2: Before I stumbled across the blending technique, I would have
said no. Now, I think it is worth a try to go to 3 stops. The
blending technique I describe is extremely simple and
straightforward, it takes more time to describe than to execute.
The real problem is getting paired images that are exactly the
same. I used the auto bracket feature and the remote release.
Even then I picked up some changes in position of the leaves of the
tree in the foreground.

Q3: I'm sorry, I just don't understand what you are suggesting.

Chuck

Idiau Duvilaj said:

Interesting test. It raises a few questions in my mind:

• Would your conclusion be that by using blending we can extend the

dynamic range of the G3 (and probably most CCD-based cameras) by 1
stop without too much effort and by 2 stops with a bit more work?

• Do you think attempting to go beyond 2 stops is worthwhile?
• Do you think that by stacking two under-exposed photos with the

normally exposed one we would also get rid of much of the random
noise?

Click to expand...

Click to expand...

Idiau Duvilaj said:

I came up to a particular
piece of blending software FDRExposer that seems to offer some kind
of solution with the concept of an "anchor image". I have not tried
it, so i cannot say whether it is worth anything. That blending
software also seems to handle 48bit tiff, so this could fix the
major Photoshop limitation of layers working in 8bits per channel
only.

There are other issues with blending, including the "transfer
response curve" that makes high quality results difficult to
achieve. It seems that FDRExposer attempts to tackle these issues.

I wonder if anyone has tried that software? You'll find a
description at

http://www.andreas-schoemann.de/fdrtools/fdrexposer/fdrexposer_e.php

Click to expand...

Man-Fai Wong said:

is not bad at all if it really works well for high quality results
and is easy to use.

Man

Idiau Duvilaj said:

I came up to a particular
piece of blending software FDRExposer that seems to offer some kind
of solution with the concept of an "anchor image". I have not tried
it, so i cannot say whether it is worth anything. That blending
software also seems to handle 48bit tiff, so this could fix the
major Photoshop limitation of layers working in 8bits per channel
only.

There are other issues with blending, including the "transfer
response curve" that makes high quality results difficult to
achieve. It seems that FDRExposer attempts to tackle these issues.

I wonder if anyone has tried that software? You'll find a
description at

http://www.andreas-schoemann.de/fdrtools/fdrexposer/fdrexposer_e.php

Click to expand...

Click to expand...

Vladimir Brajovic said:

I couldn't reproduce the result using "darken" blending mode.
Simply the top layer(in darken mode) dominates and turning the
bottom layer on or off doesn't change anything.

There are other ways to blend multiple expsures
http://www.luminous-landscape.com/tutorials/blended_exposures.shtml

Or if you want to enhance shadows in a single dark exposure
http:///www.shadowilluminator.org

Click to expand...

John Bäckstrand said:

There is also HDRShop:

http://www.debevec.org/HDRShop/

Click to expand...

Idiau Duvilaj said:

John Bäckstrand said:

There is also HDRShop:

http://www.debevec.org/HDRShop/

Click to expand...

By Jove! I have just discovered this list of exposure blenders...
It's too much! There must be much more interest in this than I
thought.

Image Stacker : http://www.tawbaware.com/imgstack.htm
Optipix Blend Exposure :
http://www.reindeergraphics.com/optipix/guide/blend.shtml
HDR Shop :
http://athens.ict.usc.edu/HDRShop/
Reinhard HDR Tonemapping Plugin for HDR Shop:
http://www.gregdowning.com/HDRI/tonemap/Reinhard/
Photomatix: http://www.multimediaphoto.com/photomatix/index.html
Full Dynamic Range Exposer:
http://www.andreas-schoemann.de/fdrtools/fdrexposer/fdrexposer_e.php
Contrast Blending (with Photoshop):
http://www.erik-krause.de/blending/
DRI: http://www.fredmiranda.com/DRI/index.html
Gradient Domain HDR Compression:
http://www.cs.huji.ac.il/~danix/hdr/
HDR Reduction via Maximization of Image Information:
http://www.cs.wright.edu/people/faculty/agoshtas/hdr.html
Anabuilder: http://anabuilder.free.fr

Click to expand...