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ADOBE PHOTOSHOP CS5 DESIGN 17

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					                                                  Creating Channel Masks            499

      Another way to add a vector mask is to select your desired layer, draw a work
      path with the Pen tool or one of the shape tools, and then select Layer➪
      Vector Mask➪Current Path.


      Managing vector masks
      Here are a few vector mask tips. You can perform the following tasks:

       ✓ Edit a vector mask path. Use the pen tools and the Direct Selection tool,
         as described in Book III, Chapter 2.
       ✓ Add multiple shapes or paths to the existing vector mask. All you need
         to do is drag another shape with any of the shape tools. Or add another           Book VI
         path with the Pen tool. You can also add, delete, and intersect shapes           Chapter 3
         and paths using the Add, Subtract, Intersect, and Exclude icons in the




                                                                                          Advanced Masking
                                                                                          Getting Exact with
         Options bar.




                                                                                             Techniques
       ✓ Remove a vector mask from a layer. Drag the thumbnail to the trash
         can icon in the Layers panel or choose Layer➪Vector Mask➪Delete. You
         can also click the Delete (trash can) icon in the Masks panel.
       ✓ Disable (temporarily hide) or enable a vector mask. Shift-click the
         vector mask thumbnail or choose Layer➪Vector Mask➪Disable (or
         Enable). You can also click the
         Disable/Enable Mask icon in the
         Masks panel.
       ✓ Rasterize a vector mask. Rasterizing
         (or turning the mask into a pixel-
         based image) converts the vector
         mask into a layer mask. Choose
         Layer➪Rasterize➪Vector Mask.
       ✓ Apply layer styles to vector
         shapes. This is a quick-and-easy
         way to create buttons for a Web
         page or a custom logo, as shown in
         Figure 3-5. Just select the layer, not
         the vector mask, and choose
         Layer➪Layer Style. Select your
         style of choice. For details on layer Figure 3-5: Adding layer styles to your
         styles, see Book V, Chapter 4.         shapes can make them really shine.



Creating Channel Masks
      Photoshop’s channel masks are probably the most time-consuming masks to
      use because they require a lot of manual labor. Not heavy lifting, mind you,
      but work with the tools and commands in Photoshop.
500   Creating Channel Masks


         But, don’t get me wrong; it’s time well spent. Channel masks can usually
         accurately select what the other Photoshop tools can only dream about —
         wisps of hair, tufts of fur, a ficus benjamina tree with 9,574 leaves.

         You can create a channel mask in a lot of ways, but I’m here to offer you one
         that works most of the time. To create a channel mask, follow these steps:

          1. Analyze your existing channels to find a suitable candidate to use to
             create a duplicate channel.
             This is usually the channel with the most contrast between what you
             want and don’t want. For instance, in my example, the Blue channel pro-
             vided the most contrast between the windmills and the sky, which I
             wanted to mask, and the background, which I didn’t.
             To duplicate the channel, drag your desired channel thumbnail to the New
             Channel icon at the bottom of the Channels panel. After you duplicate the
             channel, it then becomes an alpha channel and is named (channel) copy.
          2. Make sure the alpha channel is selected in the Channels panel and
             choose Image➪Adjustments➪Levels.
             Using the histogram and the sliders in the Levels dialog box, increase
             the contrast between the element(s) you want and don’t want selected.
             Click OK when you’re done to close the dialog box.
          3. Select a tool, such as the Brush or Eraser tool, and paint and edit the
             alpha channel to refine the mask.
             See Figure 3-6. I used the combo of the Brush and Eraser set to Block
             mode to clean up my mask.
          4. When you complete the mask, click the Load Channel as Selection
             icon (the dotted circle icon on the far left) at the bottom of the
             Channels panel. Then, click your composite channel at the top of the
             list of channels.
             This step loads your mask as a selection, giving you that familiar selec-
             tion outline. You can also use one of my favorite keyboard shortcuts:
             Ctrl-click (Ô-click on the Mac) directly on the alpha channel to load the
             mask as a selection.
             Your selection is now ready to go.
          5. You can leave it within the original image, or drag and drop it onto
             another image with the Move tool, as I did in Figure 3-7.
             Because my new sky was darker than my original, I also darkened my
             windmills so the lighting would be more consistent. If you’ve done a good
             job, nobody will be the wiser that the two images never met in real life.
                                                  Creating Channel Masks                   501

                                                       Channel mask




                                                                                                           Book VI
                                           Original                                                       Chapter 3




                                                                                                          Advanced Masking
                                                                                                          Getting Exact with
                                                                                                             Techniques
                                                                                   Corbis Digital Stock
Figure 3-6: Use the Levels and Photoshop painting and editing tools to refine your channel mask.




                                                                                   Corbis Digital Stock
Figure 3-7: When combining multiple images, masking is usually the most accurate method.
502     Creating Channel Masks


      Putting It Together

            Masking Hair, Fur, and Other Wispy Things
            Hair, fur, fuzz, and other objects with complex or loosely defined edges can prove difficult
            to select with the run-of-the-mill selection techniques. But that’s where masking can
            save the day. Because a mask allows for a 256-level selection, it does a great job of pick-
            ing up those elusive strands of hair and such that would otherwise probably be cut off in
            the selecting process.

            Perhaps you’ve seen those photos where everyone in a composite image appears to
            have helmet hair? Here are the steps to avoid the Aqua Net look and select even the
            smallest wisp of hair:

            1.   Choose File➪Open.
                 Select an image that contains something hairy, furry, or fuzzy. A portrait is an ideal
                 choice (unless the subject is hair challenged).
                 For your first attempt at this technique,
                 starting with an image that has a
                 pretty simple and uncluttered back-
                 ground is best.
                 In my example, I used an image of a
                 pensive, young urban professional
                 shown in the figure.
            2.   Choose Window➪Channels.
                 View each channel by clicking the
                 channel name in the Channels panel.
                 Each channel is an independent gray-
                 scale image and a potential starting
                 point for a mask.
                 It’s best to start with the channel that
                 contains the most contrast between what you want to select and what you don’t. If
                 it’s a toss-up, go with the channel that makes selecting the difficult part of the image
                 easiest. (In my example, that’s the hair, so I chose the Blue channel.)
            3.   Choose Duplicate Channel from the Channels panel pop-up menu. In the Duplicate
                 Channel dialog box, name the channel mask and click OK.
                 You’ve created an alpha channel for the mask, shown in the figure. Now, you can
                 edit the mask without harming the original channel.
            4.   Make sure the alpha channel is selected in the Channels panel and choose
                 Image➪Adjustments➪Levels. Boost the contrast in the image by dragging the
                 Input sliders for shadows, midtones, and highlights.
                                                 Creating Channel Masks                503

     Make the element(s) you want to select to be all
     white or all black with a little gray in the wispy
     areas. In other words, you want to change most of
     the pixels in the image to either black or white.
     If you need help using the Levels adjustment, see
     Book VIII, Chapter 1.
     Remember, the goal is to select the person and his
     or her hair. You can do that in one of two ways:
     ✓ By selecting the person
     ✓ By selecting the background first and then                                             Book VI
         inverting the selection                                                             Chapter 3

     In a mask, traditionally, white represents a selected area, black represents an




                                                                                             Advanced Masking
                                                                                             Getting Exact with
     unselected area, and gray represents a partially selected area.




                                                                                                Techniques
     In my example, because my guy is darker than the background, I adjusted the con-
     trast to make the subject as black as I could while making the background lighter.
     You can see the result in the figure.
5.   When you’re done, click OK to close the Levels dialog box.




6.   Refine the mask by selecting the Eraser tool and selecting Block Mode from the
     Options bar.
     The Block Eraser is a great tool for cleaning up masks. It allows you to paint inside
     the mask without creating any feathered edges.
7.   Press D to access the default colors.
     Remember, the Eraser tool paints with the background color, so be sure you have
     the color you want before you drag. Press X to switch the foreground and back-
     ground colors.
                                                                                 continued
504   Creating Channel Masks

  continued
         8.   Clean up your mask by painting with black and
              white, as shown in the figure.
              Make sure to use short strokes so you can undo any
              mistakes you make.
         9.   Use the Zoom tool if you need to touch up the
              details.
              The Block Eraser tool has only one size, so you have
              to zoom in to paint thinner strokes and zoom out to
              erase a larger area.
              Remember to leave some gray around the wispy
              areas, as seen in the figure; otherwise they may
              look chopped off.
              Take your time and be as accurate as
              you can. Patience makes a big
              difference.
              If you’re not sure what you need to
              paint on the mask and you want to
              refer to the color image, simply click
              the composite channel (either RGB or
              CMYK, depending on your image) at
              the top of the Channels panel. Then
              click the mask channel again to return
              to your mask. Or you can view both the
              mask and the composite simultane-
              ously. Your mask appears as a red
              overlay.
              Your mask is refined and ready to go.
        10.   Click the first icon on the left at the
              bottom of the Channels panel to load the mask as a selection.
              Or Ctrl-click (Ô-click on the Mac) the channel mask.
              A selection marquee appears around your mask.
              If you want to soften the edge a little, you can choose Select➪Modify➪Feather and
              enter a value somewhere between 0.5 pixel (for a low-resolution image) to 2 pixels
              (for a high-resolution image). Feathering allows for a soft, natural-looking transition
              between your masked element and the background. I used a 1-pixel feather for my
              image.
        11.   Return to the composite image by clicking the RGB channel (or CMYK, if
              warranted).
              The selection outline appears in your composite image, shown in the figure.
                                                  Creating Channel Masks               505


12.   If you need to invert your selection,
      choose Select➪Inverse.
      In my example, I just filled my back-
      ground with a solid color, so I left the
      background selected.
13.   Choose Window➪Color and mix a
      color of your choice. Choose Edit➪
      Fill, and in the Fill dialog box, choose
      Foreground Color for your Contents.
      Click OK.
                                                                                                Book VI
      Photoshop now replaces the back-                                                         Chapter 3
      ground with a solid color. Check the




                                                                                               Advanced Masking
                                                                                               Getting Exact with
      edges to see how clean your mask is.




                                                                                                  Techniques
14.   Make any final edits you need
      to make.
      My guy looked like he spent too much
      time at the local tanning booth, so I
      toned down the redness in his skin by
      using the Variation commands (see
      Book VIII, Chapter 1), as shown in the
      figure.
15.   When you’re happy with your channel
      mask, save and close the file.
      It takes practice to get masking down
      to a science, but, believe me, it’s worth
      your time. Nine times out of ten, a
      channel mask lends a much better
      selection than any of the easier,
      quicker selection tools and
      techniques.
      Instead of filling the background with a color, you can also open a second image
      and, with the Move tool, drag and drop your masked element into the second image.
      A couple of things to keep in mind when compositing with two images: First, try to
      use two images whose lighting isn’t so dissimilar that it looks artificial. Take into
      account the time of day, the angle of the light, and so on. Second, try to select two
      images whose levels of focus make sense. If you need to soften one of the images,
      apply the Gaussian Blur filter. If your mask is good, your person should look right at
      home in his or her new digs.
506   Book VI: Channels and Masks
  Book VII
Filters and
Distortions
G     ot an image that needs to be sharper or
      maybe less dusty? How about an image that
needs to look like it was wrapped in plastic and
then Xeroxed on a circa-1970 photocopier? Either
way, this is the book that describes the fine-tuning
and the folly of filters.

Filters can do wonders in correcting your images,
making them look better than the original. And if
it’s special effects you’re interested in, look no fur-
ther. Filters can make your image look ripped,
sprayed, wet, hot — and just about any other
adjective you’re interested in. The best news is
that Photoshop offers Smart Filters: filters that
work their magic without damaging your pixels. If
distortions are more your thing, you won’t be dis-
appointed with the Liquify command, for which
image warping, pushing, bloating, and puckering
are daily activities.

				
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