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Working with the Magnetic Lasso tool

From: Photoshop Masking and Compositing: Fundamentals

Video: Working with the Magnetic Lasso tool

All right. We didn't really get anything done in the previous exercise, so I've reverted to the saved version of Alternative eye color.psd. I'll once again turn off the lines layer so that we can focus on the frog. In this exercise, I am going to show you a great use for the Magnetic Lasso. One of the things that bothers a lot of folks as they start using this tool is they try to get too ambitious with it. You don't want to select an entire image really using any of these tools. You are best off combining the tools together and I'll show you how that works in the next chapter.

Working with the Magnetic Lasso tool

All right. We didn't really get anything done in the previous exercise, so I've reverted to the saved version of Alternative eye color.psd. I'll once again turn off the lines layer so that we can focus on the frog. In this exercise, I am going to show you a great use for the Magnetic Lasso. One of the things that bothers a lot of folks as they start using this tool is they try to get too ambitious with it. You don't want to select an entire image really using any of these tools. You are best off combining the tools together and I'll show you how that works in the next chapter.

But for now, I just want to make a case for using this tool on small portions of an image. For example, let's say that I want to take this rear eye right there, the eye that's barely visible in the background and we want to make a commensurate change to it so that it matches this forward eye. What we want to do is select this rear eye and add it to the layer Mask, make sure you have the Magnetic Lasso tool selected and these kinds of small modifications are exactly what this tool is designed for.

So I'll click down here at the bottom of the eye like so, and then I'll click at this corner. I may actually click down here at this location, and then sort of round off the corner like that. What you want to do is you want to make sure that these edges that are getting drawn between the various points are scalloping outward if possible instead of inward, because if they start scalloping inward, that's going to give us bad effect. So the trick is to lay down as many points as you can and then up here at this obvious corner, I'll click, and I'll continue to move my cursor down trying to avoid of course that scalloping right there and I'll continue to add points along this edge until I get back to the beginning, and then I'll click in order to complete that selection outline. All right.

Now, at this point, you are probably going to want to smooth off this selection outline and give it a little bit of a blur too, so that it matches the focus of that rear eye. And the way folks typically work with this tool is they go up to the Select Menu, choose Modify, and then choose, for example, Smooth. The problem with this command is you're working on a marching ant selection, so you can't really see what you are doing, and furthermore, there's no preview associated with this dialog box. So you are not going to see the results until after you click OK. So if I apply a Radius of 3 pixels, I am really working in the dark.

I'll click the OK button, I guess that looks better, I don't really know. I can see that I've rounded off the edges a little bit. Then I might go up to the Select menu, choose Modify, and choose the Feather command in order to soften that selection, so that it matches the blur associated with the image. But again, I'm trying to modify a marching ant style selection, and I am working blind because there's no preview. So I might say, well, gosh. It looks like there is a blur of 6 pixels, I don't know, and then click OK and I really don't know if I've done what I was trying to do or not.

So I tell you what, let's undo those modifications by pressing Ctrl+Alt+Z, or Command+Option+Z on a Mac twice in a row to get rid of feather and then smooth. Then switch to the eye color layer right there, and click on its layer Mask to make it active, and we want to fill this area with white. White is currently my background color. So I'll press Alt+Backspace or Option+ Delete on the Mac in order to make that portion of the mask white which reveals the adjustment. All right. Now, I'll press Ctrl+D or Command+D on the Mac in order to deselect the image and we can already see that it's far too harsh.

So I tell you what, let's switch to the layer Mask by pressing the Alt key, or the Option key on the Mac, and clicking on that layer Mask thumbnail there in the Layers panel. Now, we see the layer Mask independently of the image so we can get a sense of what's going on, and you'll note that it's pretty garbagy. Now, the problem is we need to modify this portion of the mask without harming the forward eye which is in great shape. So somehow we need to select this right -hand region and you can do that using either of a couple of tools we've already seen; either you could switch to the Lasso tool and just go ahead and draw big broad selection around that area, or I'll go ahead and click to deselect the image.

You could even switch to the Rectangular Marquee tool and just draw a selection like so, and that's where these tools become really powerful when you're modifying the contents of an existing mask. All right. Now, we need to smooth the mask and feather it using a couple of filters. We'll start by going to the Filter menu, choosing Noise, and choosing that command that allows you to smooth off your masks which is Median. I came up with a Radius value of 6 pixels, and that ends up smoothing off those edges pretty nicely. It rounds out the corners as well, but that's going to prove to be okay once we blur this mask.

So now I'll click OK in order to accept that modification. To feather the mask, you go to the Filter menu, choose Blur, and choose Gaussian Blur. Gaussian Blur and Feather are actually exactly the same command. They work the same except that Gaussian Blur obviously works on the mask as opposed to a selection outline, and you can preview the results. Now, I found that a Radius value of 4 pixels worked out nicely. So I'll go ahead and dial in that value and click OK. All right. Now, you can click inside the Image window in order to deselect the mask. All right.

Now, let's see the results by Alt+ Clicking or Option+Clicking on that layer Mask thumbnail again, and you can see that we have some smoother softer transitions. So just to get a sense of the contribution of the adjustment layer, I'll turn its eyeball off for a moment. So you can see that the original eyes are much redder. Now, I'll turn that adjustment back on, so we can see the newly modified colors. Now, one more thing about the Magnetic Lasso, I am going to go ahead and switch back to it here. If I were you, I'd wonder what's going on with these options, because typically, the options up here in the options bar do a lot to control the accuracy of the automated selection tools.

However, in this case, I don't find them to be all that overwhelmingly powerful. The Width value sets how far the points and segments can vary from the edges that are automatically detected by the tool. A width of 10 pixels works out pretty nicely. However, if you find that you need more precise results, you can reduce that value and you can do so from the keyboard by pressing the Bracket keys. Those are the keys to the right of the P as in Paul key on an American keyboard. So pressing the Left-bracket key will reduce the Width value, pressing the Right-bracket key will increase that value, and you can experiment with that as desired.

The Contrast option determines how much contrast, how much luminance contrast is required inside the image in order to count as an edge. So once again, lower values are going to give you more precise control. However, reducing either Width or Contrast will also increase the complexity and potentially the scalloping associated with that final selection outline. So that's something to bear in mind. Frequency sets how frequently the tool lays down Anchor Points. Again, you can experiment with this value as desired.

But, between you and me, it verges on a kind of black magic, not exactly sure what that 57 even means. Then finally, we've got this option for those of you who own Wacom Tablets and the like. You've got the option to use the Stylus Pressure to change the Width setting on-the-fly. But, for my money, and this is based on years of experience with this tool, I leave these values as set by default. All right. That takes care of the Lasso tools. In the next exercise, I'll show you how to use the Quick Selection tool.

Show transcript

This video is part of

Image for Photoshop Masking and Compositing: Fundamentals
Photoshop Masking and Compositing: Fundamentals

128 video lessons · 31043 viewers

Deke McClelland

Expand all | Collapse all
  1. 15m 25s
    1. Welcome
      1m 12s
    2. Loading my custom dekeKeys shortcuts
      3m 45s
    3. Adjusting the color settings
      4m 29s
    4. Setting up a power workspace
      5m 59s
  2. 1h 0m
    1. The channel is the origin of masking
      1m 54s
    2. The Masks and Channels panels
      4m 48s
    3. How color channels work
      7m 7s
    4. Viewing channels in color
      3m 24s
    5. How RGB works
      4m 12s
    6. Single-channel grayscale
      5m 12s
    7. Mixing a custom "fourth" channel
      5m 15s
    8. The other three-channel mode: Lab
      5m 45s
    9. A practical application of Lab
      4m 55s
    10. The final color mode: CMYK
      7m 5s
    11. Introducing the Multichannel mode
      5m 56s
    12. Creating a unique multichannel effect
      5m 18s
  3. 44m 27s
    1. The alpha channel is home to the mask
      1m 40s
    2. The origins of the alpha channel
      3m 40s
    3. How a mask works
      7m 10s
    4. Making an alpha channel
      4m 2s
    5. Using the new channel icons
      6m 27s
    6. Saving an image with alpha channels
      4m 23s
    7. Loading a selection from a channel
      4m 7s
    8. Putting a mask into play
      3m 55s
    9. Loading a selection from a layer
      4m 27s
    10. Loading a selection from another image
      4m 36s
  4. 1h 0m
    1. The mask meets the composition
      1m 8s
    2. Viewing a mask as a rubylith overlay
      6m 13s
    3. Changing a mask's overlay color
      5m 34s
    4. Painting inside a mask
      6m 3s
    5. Cleaning up and confirming
      5m 18s
    6. Combining masks
      5m 10s
    7. Painting behind and inside a layer
      5m 27s
    8. Blending image elements
      6m 1s
    9. What to do when layers go wrong
      6m 3s
    10. Hiding layer effects with a mask
      4m 22s
    11. Introducing clipping masks
      5m 29s
    12. Unclipping and masking a shadow
      3m 50s
  5. 1h 35m
    1. The seven selection soldiers
    2. The marquee tools
      6m 31s
    3. The single-pixel tools (plus tool tricks)
      6m 48s
    4. Turning a destructive edit into a layer
      5m 34s
    5. Making shapes of specific sizes
      7m 7s
    6. The lasso tools
      5m 49s
    7. Working with the Magnetic Lasso tool
      7m 19s
    8. The Quick Selection tool
      8m 13s
    9. Combining Quick Selection and Smudge
      4m 52s
    10. The Magic Wand and the Tolerance value
      6m 55s
    11. Contiguous and Anti-aliased selections
      6m 58s
    12. Making a good selection with the Magic Wand
      6m 34s
    13. Selecting and replacing a background
      6m 55s
    14. Resolving edges with layer effects
      7m 52s
    15. Adding lines of brilliant gold type
      7m 28s
  6. 1h 11m
    1. Selections reign supreme
    2. Introducing "selection calculations"
      4m 19s
    3. Combining two different tools
      7m 29s
    4. Selections and transparency masks
      5m 17s
    5. Selecting an eye
      7m 1s
    6. Masking and blending a texture into skin
      5m 1s
    7. Painting a texture into an eye
      4m 19s
    8. Combining layers, masks, channels, and paths
      4m 54s
    9. Moving selection outlines vs. selected pixels
      5m 36s
    10. Transforming and warping a selection outline
      7m 45s
    11. Pasting an image inside a selection
      7m 26s
    12. Adding volumetric shadows and highlights
      6m 54s
    13. Converting an image into a mask
      4m 42s
  7. 1h 5m
    1. The best selection tools are commands
      1m 5s
    2. Introducing the Color Range command
      5m 59s
    3. Working in the Color Range dialog box
      7m 7s
    4. Primary colors and luminance ranges
      4m 12s
    5. A terrific use for Color Range
      4m 57s
    6. Introducing the Quick Mask mode
      7m 43s
    7. Moving a selection into a new background
      5m 43s
    8. Smoothing the mask, recreating the corners
      8m 43s
    9. Integrating foreground and background
      4m 44s
    10. Creating a cast shadow from a layer
      2m 51s
    11. Releasing and masking layer effects
      3m 11s
    12. Creating a synthetic rainbow effect
      4m 30s
    13. Masking and compositing your rainbow
      4m 46s
  8. 1h 17m
    1. The ultimate in masking automation
      1m 6s
    2. Introducing the Refine Mask command
      6m 58s
    3. Automated edge detection
      8m 23s
    4. Turning garbage into gold
      6m 19s
    5. Starting with an accurate selection
      7m 11s
    6. Selection outline in, layer mask out
      7m 48s
    7. Matching a scene with Smart Filters
      4m 29s
    8. Cooling a face, reflecting inside eyes
      4m 45s
    9. Creating a layer of ghoulish skin
      4m 28s
    10. Adding dark circles around the eyes
      5m 20s
    11. Creating a fake blood effect
      5m 38s
    12. Establishing trails of blood
      7m 40s
    13. Integrating the blood into the scene
      7m 3s
  9. 1h 48m
    1. Using the image to select itself
      1m 37s
    2. Choosing the ideal base channel
      5m 7s
    3. Converting a channel into a mask
      6m 34s
    4. Painting with the Overlay mode
      7m 27s
    5. Painting with the Soft Light mode
      5m 55s
    6. Mask, composite, refine, and blend
      4m 40s
    7. Creating a more aggressive mask
      7m 2s
    8. Blending differently masked layers
      7m 0s
    9. Creating a hair-only mask
      6m 0s
    10. Using history to regain a lost mask
      3m 42s
    11. Separating flesh tones from hair
      8m 28s
    12. Adjusting a model's color temperature
      4m 30s
    13. Introducing the Calculations command
      7m 22s
    14. Extracting a mask from a Smart Object
      6m 34s
    15. Integrating a bird into a new sky
      5m 40s
    16. Creating synthetic rays of light
      6m 4s
    17. Masking and compositing light
      7m 39s
    18. Introducing a brilliant light source
      7m 5s
  10. 1h 34m
    1. The synthesis of masking and compositing
      1m 36s
    2. White reveals, black conceals
      6m 45s
    3. Layer masking tips and tricks
      5m 8s
    4. Generating a layer mask with Color Range
      5m 38s
    5. The Masks panel's bad options
      5m 18s
    6. The Masks panel's good options
      3m 50s
    7. Creating and feathering a vector mask
      3m 42s
    8. Combining pixel and vector masks
      3m 50s
    9. Working with path outlines
      7m 10s
    10. Combining paths into a single vector mask
      7m 52s
    11. Sharpening detail, reducing color noise
      4m 27s
    12. Recreating missing details
      8m 49s
    13. Masking glass
      5m 50s
    14. Refining a jagged Magic Wand mask
      5m 53s
    15. Masking multiple layers at one time
      5m 15s
    16. Establishing a knockout layer
      6m 6s
    17. Clipping and compositing tricks
      7m 37s
  11. 1m 17s
    1. Next steps
      1m 17s

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