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Lightroom vs. Apertu Curves



 
 
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  #21  
Old August 12th 14, 06:16 PM posted to rec.photo.digital
Sandman
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Posts: 5,467
Default Lightroom vs. Apertu Curves


In article 2014081210020227645-savageduck1@REMOVESPAMmecom, Savageduck wrote:

http://sandman.net/files/aperture_curves_normal.png

Here you see the normal 8 bit of image data with hot highlighted.

http://sandman.net/files/aperture_curves_extended.png

And here you see me having extended the white point into the data in the
extended range, clearly showing that less is blocked. This image shows you
what is truly blocked in the sensor data.


You have shown all that before and nothing has changed by repeating yourself.


I had hopes you'd understand what I was in reference to by explaining it
further.

You haven't extended anything other than the sensitivity on my BS
meter.


Wtf? What's with the teenage attitude?

All you have shown us is the clipping beyond that WP spike. Show
us where you get this figure between 255 & 300 that represents workable
data. All that stuff in that red zone is gone never to be seen again.


Look at the pictures again - the first shows the red blob larger than then
in the second. That means that in the second image, there is more image
data. That's because I have compressed the dynamic range.

Perhaps a different example where you didn't have blown highlights
might have been better for the purposes of this discussion. The
image you used had too many exposure issues (see above) to truly
illustrate your point.


Not at all. I am not interested in the blown out parts,


You should be, they are an indication of bad metering and/or bad
exposure setting, and dare i say it questionable shooting on your part.


Which would be interesting if this was a thread about metering, eexposure
or shooting. It is not. It's about the capabilities of software, regardless
of photo. The photo I picked is indeed a very poor photo, but clearly
illustrates my point.

perhaps if you had waited another 30-45 seconds for the Sun to drop
behind that roof you might have had a better chance of selling it.


Selling... what?

...and it is in the blown parts you claim there is this phantom data
which somehow exists in this mysterious area beyond 255.


Is the concept of larger dynamic range in RAW totally lost on you? Is this
just a case of you not knowing that the sensor of a given digital camera
can capture more data than your monitor can show? You seem oblivious to
this fact where data beyond an 8-bit scope is "phantom" data to you.

The data is clearly shown in my images, unquestionably! If you have
questions or there are parts you do not understand, do not be afraid to ask
and I'll try to explain further.

I am interested in
the parts that aren't blown out, but can't fit in a 8 bit colorspace and
thus *appear* blown out. Parts that *are* blown out in 8 bit but not in 11,
12 or 14 bits. If this was a Hasselblad shot, there would be even more data
hiding in the extended range outside the scope of your monitor.


But it isn't a Hassy shot, the highlights are blown, and there is
nothing to recover.


As I have shown you in two images, there *IS* data to recover and I
recovered it. What part of that do you not understand?

http://sandman.net/files/aperture_curves_normal.png

Unedited 8 bit view of image

http://sandman.net/files/aperture_curves_extended.png

Recovered data from 11 bit image data. See how the images differ?

If there was you should be able to do that with the magic tools you have
available in Sweden, and then present us with this wonderful image with
its extended histogram data restored in all its glory, but you can't
because that data does not exist on your computer or mine. The best that
can be done is band-aid work.


See above, and you see the recovered data.

Just for once relax, take a deep breath and note how in the second image,
there is data information in the extended range in the curves editor, how
I've moved the white point to the right of the normal 8 bit range and it is
now covering all of the original 11 bit of data.

That's recovered data.

And again - if something confuses you or you just didn't know there was
such data, just let me know and I'll try to help explaining it. Not meant
sarcastically or anything. I just assumed that everyone knew that RAW data
had more bits of data than what your monitor could show, or what could be
stored in the JPG format.

In fact, if you've ever used Photomatix, or any other HDR tool, you
probably know that they don't need to have several bracketed images to
perform HDR tone mapping, you can do it with just one RAW file, because the
software can tone map the extended range of sensor data found in that one
file.

These days, Photomatix will allow you to tone-map a JPG file as well, but
it has much much less data to work with so the end result is a far cry from
what you get with a HDR images, let alone bracketed images.

In short, one RAW file with 12 bit of image data from my Nikon could quite
possibly cover the dynamic range of three bracketed JPG images.


--
Sandman[.net]
  #22  
Old August 12th 14, 06:21 PM posted to rec.photo.digital
Sandman
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Posts: 5,467
Default Lightroom vs. Apertu Curves

In article , Floyd L. Davidson wrote:

Sandman:
I am not talking about data that may or may not be outside the 11
bit data in the RAW file, I am talking about the data that exists
between the 8 bit data you can see on your monitor and the 11 bit
of data that exists in the image.


I thought your first reference to 11 bit data was a typo, but here
you are repeating that. It isn't 11 bit data. The ARW file is 14
bits per sample.


For once, you're right (must feel good, right?).

I looked it up before making my initial post but must have stumbled on bad
data.

blown out in 8 bit but not in 11, 12 or 14 bits. If this was a
Hasselblad shot, there would be even more data hiding in the
extended range outside the scope of your monitor.


It has nothing to do with color space.


When working with the RAW conversion stage, set brightness (or
"exposure" if they call it that) correctly. Gamma and other
parameters may interact with it to some degree.


The primary reason for adjusting brightness and gamma, or in fact
for using a curves tool too, in the converter stage rather than
later, is because interpolation the RAW data produces a 16 bit depth
RGB image. If the image is or has been converted to JPEG it is in
an 8 bit format. But, even in a 16 bit format the histogram will
almost always show values of 0 to 255 (8 bit depth) even if the
actual data set being edited is larger.


Captain obvious has emerged again. So, what's the problem here, you can't
understand what you read or just don't care?

The mere concept of having the information presented via a "curves"
tool is what is confusing you. They might well show it to you in
that context, but what they are doing is allowing you to go back to
the RAW converter and change brightness. If you are aware of that,
conceptually, it isn't at all hard to understand.


No one is trying to "understand" anything here, ignorant Floyd. You're just
posting obvious basic stuff that no one asked about because you can't read
to save your life.

Same old, same old, ey?



--
Sandman[.net]
  #23  
Old August 12th 14, 06:29 PM posted to rec.photo.digital
nospam
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Posts: 24,165
Default Lightroom vs. Apertu Curves

In article , Floyd L. Davidson
wrote:

Perhaps a different example where you didn't have blown highlights
might have been better for the purposes of this discussion. The
image you used had too many exposure issues (see above) to truly
illustrate your point.


Not at all. I am not interested in the blown out parts, I am interested in
the parts that aren't blown out, but can't fit in a 8 bit colorspace and
thus *appear* blown out. Parts that *are* blown out in 8 bit but not in 11,
12 or 14 bits. If this was a Hasselblad shot, there would be even more data
hiding in the extended range outside the scope of your monitor.


It has nothing to do with color space.

When working with the RAW conversion stage, set
brightness (or "exposure" if they call it that)
correctly. Gamma and other parameters may interact with
it to some degree.


brightness != exposure.

lightroom used to have brightness, but it was removed in the current
version since exposure works much better.

brightness can be put back by choosing pv 2010 (or earlier), but that's
not recommended.

The primary reason for adjusting brightness and gamma,
or in fact for using a curves tool too, in the converter
stage rather than later, is because interpolation the
RAW data produces a 16 bit depth RGB image. If the
image is or has been converted to JPEG it is in an 8 bit
format. But, even in a 16 bit format the histogram will
almost always show values of 0 to 255 (8 bit depth) even
if the actual data set being edited is larger.


there is no later stage.

everything is done in raw (assuming original raw) using floating point
math and prophoto rgb colour space. always.

it is never converted to jpeg until the image is exported *after* all
adjustments are complete.

Note that the horizontal scale on an histogram is rarely
ever marked in fstops. Cameras generally have a very
non linear scale while editors are "somewhat" close.
But just because there are 6 or 8 or 16 vertical index
marks on a histogram does not suggest the number of
fstops of range covered. (Histograms of JPEG images
cover about 9.5 fstops.)


true but not relevant.

The mere concept of having the information presented via
a "curves" tool is what is confusing you. They might
well show it to you in that context, but what they are
doing is allowing you to go back to the RAW converter
and change brightness. If you are aware of that,
conceptually, it isn't at all hard to understand.


again, you don't understand how the software works.

there is no going back to the raw converter. everything is always done
in raw, and in a non-destructive manner.

there are specific sliders for exposure (not brightness) and contrast
but it can also be done with curves and more work.
  #24  
Old August 12th 14, 06:29 PM posted to rec.photo.digital
nospam
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Posts: 24,165
Default Lightroom vs. Apertu Curves

In article , Floyd L. Davidson
wrote:

Here's an example of a feature I'm missing in Lightroom.

I use curves extensively, it's the holy grail of exposure editing.
If you're not using it, start using it!

A curves tool does not edit exposure

Captain literal strikes again.

The fact is that a curves tool does not change
"exposure" (brightness is the correct term). It is a
tone mapping tool.


adjusting exposure is not the same as adjusting brightness.


Isn't that rather obvious from what I said.


no. exposure does not change brightness or contrast. it changes
exposure which is why it's called exposure and not brightness or
contrast.

"Exposure"
can only be changed with shutter speed and aperture,
before the picture is taken.


in an ideal world, it's correct when taken, but that's almost never the
case, which is why can also be adjusted afterwards.

Which does not stop
several software programs from incorrectly labeling the
brightness adjustment as "exposure".


maybe some apps do but not all.

in fact, adjusting brightness or contrast is rarely needed, since
levels & curves do a much better and more effective job.


Curves, as I've noted, simply doesn't do that and
therefore cannot be "more effective".


it does do that, and is more effective because some implementations of
brightness and contrast can clip.

Until you understand that, all you'll do is make silly
statements such as you did for the rest of your post.


take your own advice.

you don't use the software being discussed, which would be step one.


I suppose for someone who doesn't understand it that would seem to
be true. It isn't.


so far, what you've said does not apply to the software he's using.
  #25  
Old August 12th 14, 06:29 PM posted to rec.photo.digital
nospam
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Posts: 24,165
Default Lightroom vs. Apertu Curves

In article , Floyd L. Davidson
wrote:

Here's an example of a feature I'm missing in Lightroom.

I use curves extensively, it's the holy grail of exposure editing. If
you're not using it, start using it!

A curves tool does not edit exposure, it changes the
tone mapping. You are only moving points between the
maximum white and the maximum black in relation to each
other.

What you want to adjust, for the purposes stated, are
brightness and contrast. A 'contrast' adjustment changes
the data's range of darkness and brightness. A
'brightness' adjustment moves the range toward one end
or the other of the scale. A curves tool doesn't move
the range nor does it compress or expand it. Curves
moves a portion of the range in one direction or the
other, but cannot go past either end. Areas within the
range are compress and expanded, but not the range.


curves can easily adjust brightness or contrast and even includes
presets to do so.


That is not true. It can only remap tones within the
preset confines that exist.


it is true and the confines aren't what you think they are.

When done with a RAW converter brightness and contrast
adjustments can be dramatic in effect. If you try it in
an editor with the RGB image produced by the converter
the effect will be significantly reduced, and in
particular if the image has been formatted and saved as
a JPEG.


lightroom *only* works on the raw data (assuming the original is a raw,
that is, otherwise it obviously can't).


And since it can and does do both, we can't assume that
it is either.


there's no need to assume anything. how it works is well understood.

lightroom works with what you give it. if it's raw, it works on raw. if
it's jpeg, it works on jpeg.

very straightforward, and very obvious.

the workflow is exactly the same, with the only difference being that
the quality *may* be a little lower for some actions if the source is
jpeg (it depends on what's done) and for others, identical.

regardless, the workflow is the same no matter whether it's raw or jpeg
and there is no perceptual difference with any adjustments.


Abject ignorance.


that describes you.

what i said is correct.

you don't use lightroom and are once again, talking about what you do
not know.

i suspect you'll say that's not possible, but it is.


and you did exactly what i thought.
  #26  
Old August 12th 14, 07:03 PM posted to rec.photo.digital
Sandman
external usenet poster
 
Posts: 5,467
Default Lightroom vs. Apertu Curves

In article , Floyd L. Davidson wrote:

Floyd L. Davidson:
The fact is that a curves tool does not change "exposure"
(brightness is the correct term). It is a tone mapping tool.


nospam:
adjusting exposure is not the same as adjusting brightness.


Isn't that rather obvious from what I said. "Exposure" can only be
changed with shutter speed and aperture, before the picture is
taken. Which does not stop several software programs from
incorrectly labeling the brightness adjustment as "exposure".


God, you're ignorant.

An "exposure" slider in software is *not* a brightness editor. It does
*not* edit brightness. A true brightness slider edits all color values
uniformly, increasing or decreasing the color value of every pixel.

This is how the brightness slider have worked in Photoshop since the dawn
of time, until CS5 (I think) where they changed it, but you can still use
it if you click the "Use legacy" checkbox.

The new PS brightness slider spreads the spectrum from the bottom, meaning
that darker tones are changed less than brighter tones.

An *exposure* slider focuses on the midrange, trying to emulate (yes, Eric,
this is where emulate is the proper word) how the exposure of the camera
works.

With the base values of rgb(0, 30, 250), these are the results:

True brightness +10: rgb(10, 40, 255)
New PS brightness +10: rgb(3, 36, 255)
Exposure +10: rgb(3, 40, 253)

Using curves, you can edit the whitepoint, which works exactly like the new
brightness editor in PS, meaning it extends the range beyond the
colorspace.

No one wants or use a brightness editor, they're worthless. That's why
exposure and curves white point gives you the control needed. I much prefer
the curves way, as anyone should.

nospam:
in fact, adjusting brightness or contrast is rarely needed, since
levels & curves do a much better and more effective job.


Curves, as I've noted, simply doesn't do that and therefore cannot
be "more effective".


It does, you just don't know anything about these matters.

Floyd L. Davidson:
Until you understand that, all you'll do is make silly
statements such as you did for the rest of your post.


nospam:
take your own advice.


you don't use the software being discussed, which would be step
one.


I suppose for someone who doesn't understand it that would seem to
be true. It isn't.


Ironic.


--
Sandman[.net]
  #27  
Old August 12th 14, 07:29 PM posted to rec.photo.digital
Savageduck[_3_]
external usenet poster
 
Posts: 16,487
Default Lightroom vs. Apertu Curves

On 2014-08-12 17:16:53 +0000, Sandman said:


In article 2014081210020227645-savageduck1@REMOVESPAMmecom,
Savageduck wrote:

http://sandman.net/files/aperture_curves_normal.png

Here you see the normal 8 bit of image data with hot highlighted.

http://sandman.net/files/aperture_curves_extended.png

And here you see me having extended the white point into the data in the
extended range, clearly showing that less is blocked. This image shows you
what is truly blocked in the sensor data.


You have shown all that before and nothing has changed by repeating yourself.


I had hopes you'd understand what I was in reference to by explaining it
further.

You haven't extended anything other than the sensitivity on my BS
meter.


Wtf? What's with the teenage attitude?

All you have shown us is the clipping beyond that WP spike. Show
us where you get this figure between 255 & 300 that represents workable
data. All that stuff in that red zone is gone never to be seen again.


Look at the pictures again - the first shows the red blob larger than then
in the second. That means that in the second image, there is more image
data. That's because I have compressed the dynamic range.

Perhaps a different example where you didn't have blown highlights
might have been better for the purposes of this discussion. The
image you used had too many exposure issues (see above) to truly
illustrate your point.

Not at all. I am not interested in the blown out parts,


You should be, they are an indication of bad metering and/or bad
exposure setting, and dare i say it questionable shooting on your part.


Which would be interesting if this was a thread about metering, eexposure
or shooting. It is not. It's about the capabilities of software, regardless
of photo. The photo I picked is indeed a very poor photo, but clearly
illustrates my point.

perhaps if you had waited another 30-45 seconds for the Sun to drop
behind that roof you might have had a better chance of selling it.


Selling... what?

...and it is in the blown parts you claim there is this phantom data
which somehow exists in this mysterious area beyond 255.


Is the concept of larger dynamic range in RAW totally lost on you? Is this
just a case of you not knowing that the sensor of a given digital camera
can capture more data than your monitor can show? You seem oblivious to
this fact where data beyond an 8-bit scope is "phantom" data to you.


I record 14-Bit NEFs on my DSLR. I adjust those 14-bit RAW files in
either LR or ACR. After conversion I work in 16-bit mode. The only time
I work in 8-bit is the occasional jpeg. All of my images in LR are
either NEF, CR2, DNG, 16-bit PSD, or 16-bit TIF. My 8-bit JPEGs are
produced via the LR export dialog and exist elsewhere.
I don't have an 8-bit workflow until I export from LR to produce a JPEG
version of what is in my LR catalog.

The data is clearly shown in my images, unquestionably! If you have
questions or there are parts you do not understand, do not be afraid to ask
and I'll try to explain further.


Don't bother, I am not going to be using Aperture.

I am interested in
the parts that aren't blown out, but can't fit in a 8 bit colorspace and
thus *appear* blown out. Parts that *are* blown out in 8 bit but not in 11,
12 or 14 bits. If this was a Hasselblad shot, there would be even more data
hiding in the extended range outside the scope of your monitor.


But it isn't a Hassy shot, the highlights are blown, and there is
nothing to recover.


As I have shown you in two images, there *IS* data to recover and I
recovered it. What part of that do you not understand?

http://sandman.net/files/aperture_curves_normal.png

Unedited 8 bit view of image

http://sandman.net/files/aperture_curves_extended.png

Recovered data from 11 bit image data. See how the images differ?


I see that you adjusted the linear curve on the right down which
brought the highlight levels down in the upper right of the image. You
didn't need curves to achieve that result and what was gained was
useless data. The highlights were blown and nothing you can say or do
will change that.

If there was you should be able to do that with the magic tools you have
available in Sweden, and then present us with this wonderful image with
its extended histogram data restored in all its glory, but you can't
because that data does not exist on your computer or mine. The best that
can be done is band-aid work.


See above, and you see the recovered data.


You can't quantify that data can you?

Just for once relax, take a deep breath and note how in the second image,
there is data information in the extended range in the curves editor, how
I've moved the white point to the right of the normal 8 bit range and it is
now covering all of the original 11 bit of data.

That's recovered data.


All you are showing is the clipping indicator, not data, and all I will
concede is that when you moved the linear end point on the right of the
curves histogram down, you reduced the amount of fully blown data. Most
importantly you can make the same adjustment in LR, ACR, PS anr any
other editing software which has curves adjustment capability, even
PSE, PS Touch, Pixelmator, and dare I say it GIMP.

And again - if something confuses you or you just didn't know there was
such data, just let me know and I'll try to help explaining it. Not meant
sarcastically or anything. I just assumed that everyone knew that RAW data
had more bits of data than what your monitor could show, or what could be
stored in the JPG format.


I have been doing this for some time and you are being a tad
presumptuous regarding your idea of my ignorance.

In fact, if you've ever used Photomatix, or any other HDR tool, you
probably know that they don't need to have several bracketed images to
perform HDR tone mapping, you can do it with just one RAW file, because the
software can tone map the extended range of sensor data found in that one
file.


I have Photomatix and NIK HDR Efex Pro 2, and I am well aware of the
single image tone-mapping capabilities of both

These days, Photomatix will allow you to tone-map a JPG file as well, but
it has much much less data to work with so the end result is a far cry from
what you get with a HDR images, let alone bracketed images.

In short, one RAW file with 12 bit of image data from my Nikon could quite
possibly cover the dynamic range of three bracketed JPG images.


Not really. I know the difference, but thanks for that attempt to teach
me something I have known for years.
Depending on the EV difference in those three bracketed shots you could
get decent results, or you could get results similar to a tone-mapped
single exposure. Most importantly not all single exposure RAW images
are good candidates for single image tone-mapping with either
Photomatix or HDR Efex Pro 2.



--
Regards,

Savageduck

  #28  
Old August 12th 14, 07:33 PM posted to rec.photo.digital
nospam
external usenet poster
 
Posts: 24,165
Default Lightroom vs. Apertu Curves

In article , Sandman
wrote:

Floyd L. Davidson:
The fact is that a curves tool does not change "exposure"
(brightness is the correct term). It is a tone mapping tool.

nospam:
adjusting exposure is not the same as adjusting brightness.


Isn't that rather obvious from what I said. "Exposure" can only be
changed with shutter speed and aperture, before the picture is
taken. Which does not stop several software programs from
incorrectly labeling the brightness adjustment as "exposure".


God, you're ignorant.

An "exposure" slider in software is *not* a brightness editor. It does
*not* edit brightness. A true brightness slider edits all color values
uniformly, increasing or decreasing the color value of every pixel.

This is how the brightness slider have worked in Photoshop since the dawn
of time, until CS5 (I think) where they changed it, but you can still use
it if you click the "Use legacy" checkbox.


it changed in cs3.

The new PS brightness slider spreads the spectrum from the bottom, meaning
that darker tones are changed less than brighter tones.


greatly simplifying, brightness is levels and contrast is curves, with
a single easy to use slider adjust for each.

An *exposure* slider focuses on the midrange, trying to emulate (yes, Eric,
this is where emulate is the proper word) how the exposure of the camera
works.


actually it focuses (ahem) on the highlights and shadows by protecting
them from clipping. the midrange isn't as critical.

it does emulate what would happen in the camera and is effectively the
same had you changed exposure in camera.

With the base values of rgb(0, 30, 250), these are the results:

True brightness +10: rgb(10, 40, 255)
New PS brightness +10: rgb(3, 36, 255)
Exposure +10: rgb(3, 40, 253)

Using curves, you can edit the whitepoint, which works exactly like the new
brightness editor in PS, meaning it extends the range beyond the
colorspace.


eh? what does that even mean?

No one wants or use a brightness editor, they're worthless. That's why
exposure and curves white point gives you the control needed. I much prefer
the curves way, as anyone should.


the old style brightness/contrast were broken.

they've long been fixed, with the legacy option still there for those
who learned the broken behaviour and don't want to learn how it should
be.

nospam:
in fact, adjusting brightness or contrast is rarely needed, since
levels & curves do a much better and more effective job.


Curves, as I've noted, simply doesn't do that and therefore cannot
be "more effective".


It does, you just don't know anything about these matters.


he's never used the software being discussed.

Floyd L. Davidson:
Until you understand that, all you'll do is make silly
statements such as you did for the rest of your post.

nospam:
take your own advice.


you don't use the software being discussed, which would be step
one.


I suppose for someone who doesn't understand it that would seem to
be true. It isn't.


Ironic.


isn't it?
  #29  
Old August 12th 14, 09:02 PM posted to rec.photo.digital
Floyd L. Davidson
external usenet poster
 
Posts: 5,138
Default Lightroom vs. Apertu Curves

Sandman wrote:
In article , Floyd L. Davidson wrote:

Sandman:
I am not talking about data that may or may not be outside the 11
bit data in the RAW file, I am talking about the data that exists
between the 8 bit data you can see on your monitor and the 11 bit
of data that exists in the image.


I thought your first reference to 11 bit data was a typo, but here
you are repeating that. It isn't 11 bit data. The ARW file is 14
bits per sample.


For once, you're right (must feel good, right?).

I looked it up before making my initial post but must have stumbled on bad
data.

blown out in 8 bit but not in 11, 12 or 14 bits. If this was a
Hasselblad shot, there would be even more data hiding in the
extended range outside the scope of your monitor.


It has nothing to do with color space.


When working with the RAW conversion stage, set brightness (or
"exposure" if they call it that) correctly. Gamma and other
parameters may interact with it to some degree.


The primary reason for adjusting brightness and gamma, or in fact
for using a curves tool too, in the converter stage rather than
later, is because interpolation the RAW data produces a 16 bit depth
RGB image. If the image is or has been converted to JPEG it is in
an 8 bit format. But, even in a 16 bit format the histogram will
almost always show values of 0 to 255 (8 bit depth) even if the
actual data set being edited is larger.


Captain obvious has emerged again. So, what's the problem here, you can't
understand what you read or just don't care?

The mere concept of having the information presented via a "curves"
tool is what is confusing you. They might well show it to you in
that context, but what they are doing is allowing you to go back to
the RAW converter and change brightness. If you are aware of that,
conceptually, it isn't at all hard to understand.


No one is trying to "understand" anything here, ignorant Floyd. You're just
posting obvious basic stuff that no one asked about because you can't read
to save your life.

Same old, same old, ey?


Yep, same old ****. It's pretty obvious who does
understand it and who does not.

--
Floyd L. Davidson http://www.apaflo.com/
Ukpeagvik (Barrow, Alaska)
  #30  
Old August 12th 14, 09:10 PM posted to rec.photo.digital
Floyd L. Davidson
external usenet poster
 
Posts: 5,138
Default Lightroom vs. Apertu Curves

nospam wrote:
In article , Floyd L. Davidson
wrote:

Perhaps a different example where you didn't have blown highlights
might have been better for the purposes of this discussion. The
image you used had too many exposure issues (see above) to truly
illustrate your point.

Not at all. I am not interested in the blown out parts, I am interested in
the parts that aren't blown out, but can't fit in a 8 bit colorspace and
thus *appear* blown out. Parts that *are* blown out in 8 bit but not in 11,
12 or 14 bits. If this was a Hasselblad shot, there would be even more data
hiding in the extended range outside the scope of your monitor.


It has nothing to do with color space.

When working with the RAW conversion stage, set
brightness (or "exposure" if they call it that)
correctly. Gamma and other parameters may interact with
it to some degree.


brightness != exposure.

lightroom used to have brightness, but it was removed in the current
version since exposure works much better.

brightness can be put back by choosing pv 2010 (or earlier), but that's
not recommended.


I'll tell you a secret: you cannot, under any
circumstances, change the exposure of an image with post
processing software.

The primary reason for adjusting brightness and gamma,
or in fact for using a curves tool too, in the converter
stage rather than later, is because interpolation the
RAW data produces a 16 bit depth RGB image. If the
image is or has been converted to JPEG it is in an 8 bit
format. But, even in a 16 bit format the histogram will
almost always show values of 0 to 255 (8 bit depth) even
if the actual data set being edited is larger.


there is no later stage.

everything is done in raw (assuming original raw) using floating point
math and prophoto rgb colour space. always.

it is never converted to jpeg until the image is exported *after* all
adjustments are complete.


But if it has been converted, and is now being edited...

Also "everything is done in raw" is just not true. There is
not color space for raw sensor data either.

You are confusing the RGB image with the raw sensor data.

Note that the horizontal scale on an histogram is rarely
ever marked in fstops. Cameras generally have a very
non linear scale while editors are "somewhat" close.
But just because there are 6 or 8 or 16 vertical index
marks on a histogram does not suggest the number of
fstops of range covered. (Histograms of JPEG images
cover about 9.5 fstops.)


true but not relevant.


True and very relevant, given how confused you and
Sandman are.

The mere concept of having the information presented via
a "curves" tool is what is confusing you. They might
well show it to you in that context, but what they are
doing is allowing you to go back to the RAW converter
and change brightness. If you are aware of that,
conceptually, it isn't at all hard to understand.


again, you don't understand how the software works.

there is no going back to the raw converter. everything is always done
in raw, and in a non-destructive manner.


Do you even know what "non-destructive" means? It
literally means going back and re-doing the
interpolation of raw sensor data with a raw converter.

there are specific sliders for exposure (not brightness) and contrast
but it can also be done with curves and more work.


You can't change exposure with processing software. And
a curves tool does not change the brightness nor the
contrast of an image as such. It remaps which tonal
levels are assigned to which already defined levels. It
doesn't stretch the range. It technically does not
compress the range either, but the effect is the same.

--
Floyd L. Davidson http://www.apaflo.com/
Ukpeagvik (Barrow, Alaska)
 




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