Adobe Photoshop Basics

Lesson 4i: Quick Mask & Alpha Channel Practice

Here's some practice exercises to help you get familiar with Quick Mask mode and alpha channels. (Continued below...)

Adobe Photoshop Basics • Read This First! • Course Outline • Quick Mask Intro • More Quick Mask • Alpha Channels • Mask/Selection Practice

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Exercise 1: Rounded Rectangle

1. Open a new image 100h x 200w pixels.
2. Create a rectangular selection
3. Enter Quick Mask Mode
4. Filter > Blur Gaussian Blur
5. 10 pixel radius
6. Image > Adjust > Levels
7. Drag the black and white sliders toward the center as shown in the screen shot.

Voila! A rounded rectangle selection.

Exercise 2: Coloring

Download this image. I've created several selections for various parts of the butterfly and saved the selections as alpha channels. Practice loading alpha channels and filling selections to color the image.

Exercise 3: Create a gradual fade.

1. Open any image
2. Switch to Quick Mask mode.
3. Select the linear gradient tool.
4. Set the gradient options for foreground to background.
5. Click and drag to fill the mask with a gradient (hold shift to constrain it to a straight line).
6. Exit Quick Mask mode. [Note the selection marquee appears as if the image is half selected. That's because the marquee only appears where pixels are more than 50% selected.]
7. Type D to reset default colors.
8. Hit Backspace/Delete.

Exercise 4: Combine selection tools and Quick Mask for faster selections.

1. Save this flower image.
   
2. Use the magic wand with a tolerance setting of about 100 and click on the yellow petals.
3. Most of the petals should be selected. If you need to, choose Select > Similar to select more of the petals.
4. Switch to Quick Mask Mode.
5. Make a selection of the inside of the flower and remove the mask by filling with white.
6. Invert the mask (Crtl-I/Command-I).
7. Exit Quick Mask Mode.
8. Fill with White.

Exercise 5: Create an interesting edge effect without expensive filters.

1. Open any image.
2. Make a rectangular selection staying about a half inch from all edges of the image.
3. Switch to Quick Mask Mode.
4. Go to Filter > Brush Strokes > Spatter
5. Adjust the preview window so you can see the edge of your mask and move the sliders until you are pleased with the effect. I used a radius of 20 and smoothness of 4.
6. Invert the mask.
7. Exit Quick Mask Mode.
8. Fill with white.

Try this same technique with these filters for other edge effects:

• Filter > Distort > Ripple
• Filter > Distort > Glass
• Filter > Distort > Ocean Ripple
• Filter > Artistic > Underpainting
• Filter > Blur > Gaussian Blur (10-20 pixels) followed by Filter > Pixelate > Color Halftone
• Filter > Blur > Gaussian Blur (10-20 pixels) followed by Filter > Pixelate > Crystallize
• Filter > Blur > Gaussian Blur (10-20 pixels) followed by Filter > Pixelate > Crystallize
• Filter > Blur > Gaussian Blur (10-20 pixels) followed by Filter > Pixelate > Mosaic (10)
• Filter > Sketch > Torn Edges
• Filter > Sketch > Water Paper
• Filter > Stylize > Diffuse (apply multiple times)
• Filter > Blur > Gaussian Blur (10-20 pixels) followed by Image > Adjust > Poserize (5-10)

If you'd like additional practice with selections, Quick Mask, and alpha channels, see Photoshop Masks & Selection Techniques for links to tutorials from around the Web. Be aware, however, that some of these tutorials may include features and commands we have not yet covered in this course.

Please post your results from these exercises to the Interactive Classroom.

Next > Intro to Layers

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