Channel Pulling Masks

Sometimes we get lucky. Every now and then there is actually one of those “Quick and Dirty” tricks that actually works and saves us hours of extra work. Depending on the shot “Channel Pulling” is one of those tricks.

Basically the idea here is if one of the channels in the image shows enough contrast between your subject and the background you can make a quick mask based on that channel and save yourself all the work of having to hand paint the mask.

Here’s how a quick run down on how it works. First let’s take an image like this one I got from Jupiter Images. You can see this is just a basic shot of a person against a white background. While this technique can work with more complex images I just wanted to use an easy example to get the idea across.

The first step is to go to the Channels palette and look at each of the channels in the image. This one is an RGB image so we’ll look at the Red, then Green and finally the Blue channels to see which one offers the best contrast between our subject and the background.



Looks like the Blue channel is our best bet so we’ll use that one. Next we’ll click on that channel and pull it down to the folded page icon in the menu at the bottom of the palette. (Ahhh, now you know why it's called "Channel Pulling"!) This makes a copy of the channel called “Blue copy”.

Now click on that channel in the palette menu to select it and see it on the screen.


Looking at this channel we can see that it needs a little work to be useable as a mask. Remember that you need a mask that is mostly black and white with just a little gray in between them to soften the edge and make a good transition between our subject and whatever the new background will be.

Obviously this means we need to add some contrast to the channel so we can push most of the gray values to black while making sure the rest is truly white. My preferred method for adjusting the contrast is with the “Curves” tool. You can get to the Curves adjustment by selecting Image>Adjustments>Curves from the menu, or by using the shortcut Command + M (sorry, I always have trouble remembering the PC equivalent).

Once we bring this up the adjustment itself is pretty easy, just slide the black point (in this window it’s on the lower left) over towards the right until you see the grays start to fill in to black. Then slide the White point (it’s the one on the right) over to the left until the lighter grays turn to white.


It’s good to note that you want some shades of gray around the edges. Since Black and White are the extremes shades of gray give us some feathering around the edge. How much feathering we need all depends on the image itself. As I noted in a previous post the right combination here depends on how crisp or soft the edges in the image itself are. You want your mask to have a similar amount of crispness or softness as your image. Here is a close up view of the bits of gray I’m using to feather the edges of this mask.



Now the next step is to fill in the areas that need to be black but aren’t quite there yet. Depending on what seems easiest I’ll either use a big brush to paint it in, or use the lasso tool to select those parts and then fill them with black. The same thing goes for any areas that really need to be white.


When you’ve completed this you should wind up with something that looks like this:


And now that we have our mask channel made all we need to do is turn it into a layer mask. Doing this is really simple. First make sure your layer is not set as the background layer. (Background layers cannot use layer masks.) If it is all you need to do is double click on it in the Layers palette. With this done now load the channel we just made as a selection. Again I like to do this by command clicking on the channel’s icon in the Channels palette but you can also use Select>Load Selection from the PS menu as well.

With the selection loaded look to see if the crawling ants are running around the outside of the image. Since by default White in the channel indicates the area that will be selected the channel we made will mean the background gets selected instead of the subject. No worries, all you have to do is choose Select> Inverse from the menu (Command + Shift + “i” on a Mac). This flips around the selection and now your subject is selected instead of the background.

Then the last step is to go back to the Layers palette and click on the little “Add layer mask” icon at the bottom of the Layers palette. Here’s a screen shot of it:










Now we have our layer mask and your image should look like this and you’re ready for the next job. (Don’t forget to Save your image.)

Keepin' it Simple with Layers

Maybe this comes under the “Pet Peeve” heading, but as a retoucher I see a lot of Photoshop files with lots of layers that have names like “Layer 1” or “Layer 2” etc. While I know this is Photoshop’s default naming system what happens is pretty quickly you need some sort of guide to tell what layer is doing what, a sure-fire formula for confusion!

So the suggestion I want to make here is take the brief moment it takes to name the layer in some way that helps whoever is working on the image get an idea of what that layer is for.

For instance when I’m working on a beauty shot typically I’ll have a layer where I do the majority of spotting work that’s called “Spotting”, there will also be a layer called “Stray Hairs” etc. This keeps it easy for me to tell what layer to go to when I need to make some further tweaks.

Taking this a step further if you’re combining several images into a composite image it really helps to name the layers with the names of the source images themselves. Since I work on a lot of movie posters it’s common for me to see layers named something like “boy’s head”. This at least tells me what’s on the layer, but gives me no idea which source image the head came from. Have you ever had to search an entire server looking for the correct shot so you can replace it with a cleaner version? Not fun.

But there is help. Here’s a really easy way to copy and paste the name of the source image so the layer is properly named.

Step One: With the source image open use Photoshop’s “Save As” command (Command + Shift + S on a Mac), then copy the name of the file as it shows up in the dialogue (Command + C on a Mac). Then hit the Escape key.

Step Two: Go to the Layers palette and double click on the layer named “Background”, now paste the name you copied in Step One (Command + V on a Mac).

Step Three: Now drag that layer into the composite image. Note that the layer is now named for the source file.

After doing this a few times your fingers will start to automatically go to the right key combinations and you’ll see that with just a few key strokes and a double click or two you’re done and things are organized and easy to figure out.

See, I feel better already. ;-)

Divide & Conquer: Color to B&W

Black and White imagery has had a long tradition in the world of photography. And in this digital age Photoshop goes a long way to honor that tradition giving us many different ways to convert our Color images to Black and White with more control and finesse than ever before.

What I’d like to talk about here is how to make use of some of that control to easily get results that couldn’t be achieved before without a lot of effort. Suppose you have an image like this one I took at Lake Powell a couple of years ago.

Having grown up loving the dramatic skies in Ansel Adams’ images. When I looked at this image and thought of doing a B&W version I wanted to get close to that kind of drama in the skies. But as I worked on it with Photoshop CS3’s B&W adjustment layer I realized that I wanted to also bring out the detail and contrast in the cliffs. The adjustments that gave me a cool looking sky just didn’t seem to do what I wanted in the cliffs.

Here is a screen shot showing the image adjusted for the sky along with the settings I used to get that.














And when I worked to get the detail and tonality in the cliffs the sky just seemed to miss out on the drama. Here is a screen shot showing the image adjusted for the cliffs, again with the settings.















Luckily Photoshop gives us an easy way to have the best of both adjustments. The secret is to use both adjustment layers combined with layer masks that makes sure they’re only affecting the areas we want affected. To do this all I did was start out with one adjustment, in this case the one for the cliffs, and then by painting black in the layer mask I kept this adjustment from affecting the sky.

Here is a screen shot with the layer mask shown as a Red overlay:














Then all I had to do was copy the mask from the Cliffs adjustment layer to my Sky adjustment layer and invert the values so I had the opposite part of the image covered. That looked like this:














Finally all I had to do was give a quick look over the image to make sure none of the original color was showing up in between the two adjustments and voila I had this as the finished image:

B&W APA Seminar on Aug. 9th

I'll be teaching another seminar for the Los Angeles chapter of the APA on August 9th with some of the folks from Bowhaus. Should be an interesting day.

APA/LA Digital Workshop: From Color to Black and White
Saturday August 9th, 2008
9am - 1pm
3221 Hutchinson Ave, LA CA 90034

Sign Up Today at www.apa-la.org
LIMITED SPACES FOR THIS EVENT PRE-REGISTRATION IS STRONGLY RECOMMENDED

Join us Saturday, August 9th as we present our own Dennis Dunbar and
Bowhaus' Antonis Ricos in the latest of our series of digital seminars.
They'll be taking their audience on an exploration of the Black and White
digital world.

Dennis will start things off by delving into the process of converting Color
Images to Black and White. He'll discuss what happens when you hit the
magical B&W button in Photoshop and show you how to gain control of the
process so you can fine tune the conversion to get the results you're after.
Then he'll show you how you can "Mix and Match" conversion methods to bring
out the right tonality and detail in specific areas of your image.

Then Bowhaus' Antonis Ricoss will take over the session and show you how to
get "Fine Art" Black and White prints from your images. He'll show you how
to create Digital B&W inkjet prints with rich blacks, luminous highlights
and ultra-smooth gradations. These guys really have mastered this art and
you'll see why acclaimed fine art photographers and galleries are now
choosing BowHaus to produce their Master and Exhibition prints. He'll also
show you Bowhaus' IJC/OPM software as well as their new "True Black and
White" printmaking software that you can use to create your own stunning
Digital B&W inkjet prints.

Come join us as this seminar promises to be informative and intriguing and
will help you gain the knowledge you need to move seamlessly between the
World of Color to the World of B&W.

Pre-Registration
$35 APA/LA members
$45 ASMP, LADig, Student members
$55 non-members

Day of:
$45 APA/LA members
$55 ASMP, LADig, Student members
$65 non-members

Brought to you in part by:
Bowhaus www.bowhaus.com

Good Mask - Bad Mask

One of the more frequent questions I get asked is about masking. Almost every Photoshop user has used masks at one time or another to control how one image blends with another to limit some effect to certain areas of the image. Safe to say they're used a lot. But the question that comes up is "What makes a Good Mask?"

Of course the quick answer is "It all depends on what you're trying to do." What that really means is different tasks require different qualities of masks. For instance if you just want to 'nudge' the color of one area a little bit you may get away with a softer mask that's not too exact. But if you're going to strip in a new background behind a shot of a model you're probably going to have to be a good deal more careful with your mask.

In this case the answer to our question "What makes a Good Mask?" is primarily about 'Edge Quality'. With a mask the hardness or softness of the edge is what makes for a seamless, natural looking blend or something that looks like you used a pair of scissors on. This is what we mean when we talk about 'Edge Quality'.

To get a bit deeper with this idea take a close look at the image of your model paying careful attention to the edges that naturally occur inside the image. The edge of your mask should look pretty close to how these natural edges look. Any harder than that and the image will look 'Cut Out'. Any softer and it may look 'Mushy'. (Great technical terms, eh?)

When I'm working on a mask I usually like to use a brush to paint around the edges of the part I'm masking. And while painting this edge I look to use a brush with the right size/hardness combination that looks as hard or as soft as the edge of whatever it is I'm masking. Sometimes this means I need to change the brush as I go along because maybe the depth of field means one part looks sharper than another. After I've painted this 'border' I'll then use the lasso tool and

make a series of selections based on tracing more or less along the center of the border that are then filled to make the mask.

Here is an example.

With this image the red outline you see is the border I painted, and as usual the edge of this bear varies according to the depth of field so I had to change the brush along the way as I

painted.

Here is the image with a black line showing the selection I made with the Lasso Tool.

And here is the image with the mask filled using that selection.

Now let's check the mask to make sure it's solid White and solid Black where it needs to be.

Finally here is the image with a new background.

Of course since I used the mask as a "Layer Mask" all I've done is hide the original background so the new one can show through. This means I can easily fine tune this mask to make sure everything looks just right.

Adding Glows to Hair

Lately a good deal of the work I've been doing has been with photographers who shoot high end beauty shots. Part of this work usually involves adding "a nice glow" to the hair and skin of the model. While there are several ways to do this I thought I'd share here a simple technique for adding a soft, luminous glow to the hair.

To get this effect we're going to use one of Photoshop's "Layer Blending Modes". As you're probably aware there are many blending modes we can use in Photoshop. These break down to variations on a few themes. There are blending modes that affect Contrast and Saturation, modes that darken the image and modes that lighten the image as well as a few other ones.  

Now one thing that users frequently forget is that an Adjustment Layer set to a particular blending mode even without any adjustment made to the settings of the layer itself will give you the same effect as if you had copied the image itself as a layer and set it to that same blending mode. 

The cool thing about using an Adjustment Layer (I like Curves myself) is that it adds almost nothing to the size of your file, which can be an important consideration if you're working on big files. The other cool thing is that while you don't need to play with the adjustments in the layer you can to tweak the effect you're getting. 

The mode we'll use here is the "Screen" mode. This blending mode will lighten an image based on how light the tones are in the layer. So White will have the strongest effect and Black will have the weakest effect. And all you need to do is add a Curves adjustment layer set to "Screen" blending and then make sure the mask for this layer is filled with black (this hides the effect of the layer). 

Now just look at your image and picture where you want the Glow to appear. Then  take the Brush tool and paint White in the Layer Mask wherever you want this effect to show. To really get this right you need to think a bit like an illustrator, but armed with the knowledge that you can always undo the effect by painting Black in the Layer Mask you're free to play and experiment until you're happy with the effect. If it's too strong you can also turn down the opacity of the layer to back off. 

So try it on one of your own images and see how it works. Play a bit and I bet you'll like it.

Communicating Color Effectively

Remember the story about the 3 Blind Men who are shown an animal and asked to describe it? Of course, being blind, they use their hands to feel parts of the animal and then describe what they think the animal is. The first one goes to the front and reaches out to the animal he says, “This is long, thick and strong like a python snake!” The second moves forward, feels the side of the animal and says. “This is tall and wide, like a wall!” Then the third goes to the back and says, “No, this is long and thin, like a rope!”

Meanwhile what the men don’t realize is that they are meeting an elephant, not a python, wall or rope. Communicating the proper appearance of digital images can be a lot like this. When there is no tangible image what we see depends on how our systems are setup. Without following proper color management procedures, or paying close attention to what the others in the workflow are doing we become like the blind men, describing something based on just a small part of the whole picture.

Fortunately the answer has gotten a lot easier in the last several years. Advances in software and hardware has made trusting what you see on your screen possible. By calibrating and profiling your displays using any one of the reputable packages available these days we can know that we are looking at something pretty close to “The Truth”.

If it stopped there life would be easy. But, of course, life is not so easy. In the vast majority of times there are others in the chain we need to deal with. Making sure your image is treated properly and winds up looking like you planned is one of the big challenges in the modern digital workflow.

Here communication is key. Knowing who to talk with, and what questions to ask can be critical to the process. How do you know what the client needs? And how can you get it to them in a way that makes getting it right easy? This is where groups such as UPDIG and DISC come in.

UPDIG, (the Universal Photographic Digital Imaging Guidelines, www.updig.org), is an industry-wide group created by a consortium of photographer’s groups such as APA, ASMP.EP.PPA and many more throughout the world that is focused on determining the requirements for digital images in the various parts of our industry. The folks working on UPDIG have created many resources for photographers and clients including guidelines and “Best Practices” documents for both image creators and those receiving digital images.

This work, begun at the 2004 PPE show, is on-going and continues to grow in both scope and reach. Go to their website, www.updig.org, to learn more about the group and to download the guides and best practices, then put them into practice and share them with your clients, and anyone receiving your digital images. Remember, communication is key.