Thursday, January 15, 2009

Lasso Tool

During this lesson we will take a photo of a person and remove the background using the Lasso tool.

It helps to use a photo with a distinct edge. Use a digital camera and take a photo of someone in front of the white bricks out in the hallway. This makes for a perfect candidate for the Magnetic Lasso Tool because the background will be uniform.

We will start with the Magnetic Lasso for the initial selection and learn how to clean up the selection with a Quick Mask. Later we can reposition the person on a new background. With these skills we can place people in humorous locations, the moon, an erupting volcano or at the Superbowl.

In later lessons we will learn other techniques for remove backgrounds including the Background Eraser and the Pen Tool.

Lasso Practice

Magnetic Lasso Tool The Magnetic Lasso tool detects and snaps to the edge of an object as you to trace along its outline. As you drag along the edge of an object, the tool drops fastening points to anchor the selection.

1- Take a moment to play with the Magnetic Lasso tool. Notice how you can create your own anchor by clicking the mouse.

2- Try opening your photo_in_text.jpg file and selecting your text by tracing it with the Lasso.

3- When you feel comfortable, move on to the Removing a Background lesson.

Selecting the Subject with the Lasso

Now we are ready to rock and roll. You should already have your photo taken and uploaded to your computer.

1- Open the photo in Photoshop CS3.

2- Using the Magnetic Lasso drag along the edge of an object. The tool will create a selection line along the path as you go. At key edges you may drop your own anchor by clicking the mouse.

!!! If you get an anchor that is out of position, do not freak! Just click on the DELETE key and it will step back a step.

3- Once you have come completely around the figure, click once to close the selection. You know have your person selected. You will undoubtedly find little places where the Lasso missed a spot or two. We will fix that in the steps 4-8.


Cleaning Up the Background with a Quick Mask

As you can see, the Magnetic Lasso was not perfect. It sometimes fails to detect the object around complicated spots like the hair. We can correct this fairly easily by zooming in and switching to Quick Mask mode.


The quick mask mode toggle buttons. A Quick Mask

In quick mask mode, your image is displayed with a red overlay. It represents the masked area. In this mode, your tool palette only displays white and black for the foreground and background colors. Painting with white takes away from the ruby overlay to subtract from the mask, and painting with black adds to the ruby overlay to add to the mask.

4- Click on the Quick Mask button on the toolbar to switch into quick mask mode.

5- Zoom in to where your image needs correcting.

6- Painted away the ruby overlay to reveal the parts of the subject that need to be included in the selection.

!!! Tap the space bar to temporarily bring up the Hand tool to nudge the image over if you come to the edge of the screen.

7- While still in Quick Mask mode apply a half-pixel Gaussian Blur to the mask just to soften the edge the slightest bit. Any filters you apply in quick mask mode will only effect the mask and not the image itself. Filter> Blur> Gaussian Blur

8- After applying the blur effect switch back into selection mode by pressing Q or using the toolbar toggle button.


Removing the Background

9- In the photo layer choose Selection>Invert and the

10- Press delete on the keyboard to remove the old background.

11- Save the image as background_cutout.psd before moving on.

New Background

Now its time to insert the subject in a new background. This shouldn't be a problem if you remember how to drag a photo onto an image like you did in the Photo In Text lesson.

1- Open the photo you wish to use as your new background.

2- In the photo layer of your background_cutout.psd project, use the Move tool to drag the figure onto your background.

3- Resize your figure using Command>T. You can hold down SHIFT to constrain proportions while resizing.

4- When finished, save as jpg.

1 comment:

Bollman said...
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