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PHOTOSHOP TUTORIAL: How to use Histogram and Curves to Repair Faded Images. - YouTube
Channel: JBColourisation
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On this channel I restore a lot of old
photographs.
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Today i'm going to show you how i use
curves in photoshop to restore a faded
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photograph from looking like this,
to looking like this. Let's get started
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so the very first thing i'm going to do
is give a short explanation of something
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called a histogram.
Now histograms are quite an advanced
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feature in visual editing
and can potentially be quite complicated,
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so i'll only be touching on the most
basic features of them here.
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As it's certainly not something which
you have to use to fix a faded image.
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The reason i'm bringing it up at all is
that i always want my tutorials to not
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only explain
how to do something but also to explain
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why we're doing it.
As i think that added context is really
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key to learning a new skill.
So with all that said you can bring up
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the histogram in photoshop
by going up to window and then clicking
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histogram. Now at the moment the
histogram is showing us a lot of quite
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advanced, quite complicated information
and for that reason it's quite cluttered.
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So what we can do is go to this little
drop down menu here
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and choose to go to expanded view. Now
under channel at the moment we can see
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the histogram was giving us the color
information for the picture
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but all we want is the raw brightness
values, so we can change colors
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to luminosity and now we have a much
simpler histogram to look at.
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To demonstrate more clearly how the
histogram works i created some examples.
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So a histogram is designed to visualize
the brightness values of the pixels in
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an image
by giving us a bar graph of those values.
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So in this first example i filled a
large space with black,
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a medium-sized space with gray and a
small space with white.
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And on the histogram we can see that we
have three lines
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one that's very tall, one that's
medium-sized and one that is small
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and that directly reflects what we're
seeing in the image.
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The left hand bar indicates the large
amount of black in the picture,
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the medium-sized bar indicates the
amount of grey in the picture
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and the small bar indicates the amount
of white.
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The histogram goes from left to right,
with the left hand side representing the
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darkest values
and the right hand side representing the
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lightest values.
In example 2 i inverted the image so the
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black left hand side is now
white and the white right hand side is
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now
black. The histogram reflects this
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because our smallest percentage
is now the black and it's still shown on
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the left hand side.
The grey is still shown in the center
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and our largest section
is now white and that is reflected by a
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large bar
on the right hand side. So these last two
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examples have obviously been rather
manufactured,
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i'll now show you with some pictures
that i took how the histogram works in
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practice with real photographs.
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So looking at this first example of a
pear tree surrounded by flowers
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the main thing to note is the histogram
is far more complicated
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now that we have more shades of
brightness within it. A histogram always
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looks at the image,
at least when you've set its luminosity,
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as if it were black and white.
Therefore the easiest way to see how the
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histogram is working
is to temporarily convert our image to
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black and white.
So looking at our histogram we can see
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that the furthest left hand side
and the furthest right hand side don't
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have very much information on them,
whereas obviously our previous examples
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had high spikes here.
Now this is perfectly normal in the real
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world you don't tend to come across
very many areas that are absolute pure
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black or absolute pure white
in terms of brightness. So in this
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example we can see there are a few
darker bars and that likely represents
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these dark areas
near the pear tree post and also this
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sign is quite reflective so we're
getting some bright white spikes here
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but for the most part we're not getting
anything too extreme.
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Our next example is a lot darker as an
image and therefore we have
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far less bright values on the right. In
fact, most of our values when we go to
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black and white
are at best lighter gray. Now this
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example is interesting as we don't
really have any histogram
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spikes in the center and that is because
this is quite a high contrast image.
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So we have a lot of darker information
and a lot of brighter information
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but not very much information that is
neither quite dark
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nor quite bright. Our final example here
is some very gray clouds and predictably
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our histogram is values of grey without
really any high brights
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or dark darks. So the first thing to take
away from all this i
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think is that every image has a
different histogram.
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There is no such thing as an objectively
correct histogram
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to which all images should look like. An
image such as these clouds is going to
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have a very different histogram
to this image of a bowl and that's
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perfectly fine.
The second thing to take away from this
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is that it's quite unusual,
even in an image with quite bright and
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quite dark spots,
to have pure whites and pure blacks in
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terms of your brightness values.
But what if you wanted to have pure
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blacks and pure whites within your image
well that's what you can do with a
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curves adjustment. So if i switch this on
quickly
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we'll see that our histogram has been
stretched out.
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This is afterwards this is before. We
have the same sort of peaks on the
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histogram
but they're now a lot wider and what
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we've done is stretched our histogram
out
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and what was previously our sort of
lighter gray clouds are now
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dazzling white and what was previously
slightly dark clouds
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are now black. Now obviously this is an
extreme example
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but we will be using curves in much this
same way to restore
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our faded image so let's get back to it.
So looking at our faded man's histogram
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we can more clearly see the issue.
So on the left hand side and on the
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right hand side
we just don't have any information. This
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man has got some quite dark shadow areas
on him, such as here next to his trousers,
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and also he's wearing a white shirt but
neither of those things are properly
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reflected by this histogram.
All of our values are in the center and
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are grey
and that's just not correct for this
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image. By the way if you've been seeing
this little warning
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sign up in the corner, that's not
something to worry about.
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All that represents is that this is a
rough preview histogram and not the
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final adjusted histogram
but if we click this little sign we can
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see
that actually there's not much
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difference between the two. Every time
you make any kind of change the
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histogram will update and go into
preview mode so for the most part you
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can just ignore this and leave it in
preview mode and as you've seen it's
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really not any different.
So to work with curves you'll want to go
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down to here
and click the create new fill or
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adjustment layer button
and select to add a curves adjustment.
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Before we make any adjustments you'll
want to make sure this curves adjustment
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layer
is in luminosity blend mode, so that
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we're only affecting the raw
brightness values in the image and not
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the color values as well.
If you were working with a color image
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and you wanted to affect the contrast of
the colours
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we can either use normal mode or colour
mode here
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but since i just want to work with the
black and white as it were
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brightness values i'm going to be
working in luminosity mode.
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So with that done this is the curves
control panel,
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as you can see it uses a histogram to
show you which parts of the image's
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brightness you're editing.
It also shows us, as the earlier
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histogram did, that the left and right
hand sides are rather lacking in
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information.
To start off we can quite quickly get
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rid of these gaps on the left and right
hand side
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by moving in our input black and our
output white
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closer to the center. We can do that by
dragging in
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these two arrows here. So as you see if
you click
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and drag this white arrow closer to the
center and closer to our histogram,
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if you look at our top histogram it's
now been moved
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further to the right. We can do the same
our black arrow
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and drag that closer to our histogram
and that has also stretched it out.
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Now we don't want to push this too far
at the moment and obviously we don't
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want to move in so we get absolute black
or white
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as we did with that earlier exaggerated
cloud picture
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but that is a good way of closing off
the gaps
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and if we switch our curves adjustment
on and
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off here we can see what a difference
we've already made.
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Now looking at our image, despite us
having made quite a dramatic difference,
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our gray values in the center of the
image obviously also need some work
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so we'll do that now. Now.
you can just click and drag on your
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curves line to add points
but i find the best way to adjust the
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curves line
is by using this little hand modify tool
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here.
This tool allows you to drag directly on
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the image
to adjust that selected level of
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contrast in the image.
It's far easier to demonstrate this than
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to explain it.
With the tool selected when you hover
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over the image
you'll see you get this little bouncing
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dot on your curves histogram
and this indicates which part of the
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histogram you're currently hovering over.
So if we hover over this dark point here
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next to his trousers
we can see we're on the left hand side
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of the histogram and when we hover over
his hand here that's a lot brighter
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we can see we're on the right hand side
of the histogram.
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This allows us to see exactly which part
of the histogram we'll be altering
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and then when we drag up or down on this
point we can see
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that's the part that we're brightening
or darkening.
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So it's usually better to start in the
center of your histogram i find.
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Which in this case is represented at
this spot near the man's elbow.
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Now looking at the suit we can see it's
a bit too bright.
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So if we click and drag at this point
we can darken it down.
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Conversely looking at the image we can
see that the background is a bit darker
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than we might like,
so we can drag up on that point to
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brighten it up.
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Now looking at his beard i feel that the
darker points
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need to be darker and the lighter parts
might need to be a little bit lighter
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so we can drag down on the darker points
and if we want to, drag up just a little
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on the lighter points. You can edit these
points at any time in curves
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by hovering over your chosen point until
you see this little
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movement arrows icon and then you can
drag
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it around to change the values.
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You can add as many points as you want
to this line
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it's very much down to personal
preference and what adjustments your
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particular photograph needs.
One important thing to remember is you
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don't want to drag your points too
far. So if for example i were to drag up
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this shadow information here you can see
that eventually
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you can make your shadows white and
obviously you don't want to do that.
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Generally speaking the best way to learn
curves is just to experiment with it.
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In terms of experimenting however trying
to undo an adjustment initially in
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curves
isn't quite as straightforward as it
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could be. Control,
or if you're on a Mac, command z may only
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undo
one level of error and pressing it again
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may bring that error back in again
such as this.
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If however you add an Alt in with your
control or command z
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you will instead take steps backwards in
your process, rather than doing a simple
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undo, So now if we keep pressing that,
you'll see it's removing our changes one
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by one.
If all else fails you can use this drop
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down box
in your curves adjustment to reset your
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curves.
Now if we press that once we'll see that
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all it's got rid of
is our smaller adjustments. If we press
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that again
we'll see it completely resets curves.
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Now this two stage adjustments to your
curves
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is really useful if you want to make
changes to the way that you've added
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points to the curves line,
without obviously having to redo this
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input output stage again.
So that's basically curves. One final
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thing to mention
is that if you lose your curves window
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at any point or it's closed unexpectedly
like that
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you can double click on your little
curves icon here to bring it back.
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Outside of the issue with the fading in
this picture you'll notice it has some
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small spots of damage.
If you'd like to watch some tutorials on
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how to fix damage such as this
or how to add color to images like this
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those are available on my channel.
Along with tutorials my channel has a
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large variety of videos which showcase
old photographs such as one where i
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coloured every pre-color photography us
president.
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As always any thoughts questions or
suggestions for future videos are always
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appreciated in the comments below. Thanks
for watching
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