A Few Adobe PHOTOSHOP Tips

PSA Journal, August, 2000 by Stanley Ashbrook

Creating a Line Drawing From an Image

Although Photoshop doesn't have a trace feature per se; you can easily convert an image into a line drawing using the Smart Blur filter. See figure 1 for the original image. To do so, open your image and choose Filter, Blur, Smart Blur. The resulting Smart Blur dialog box has four settings: Radius, Threshold, Quality, and Mode. Set the Quality to High and Mode to Edge Only. Then, set Radius to 2 or 3 and Threshold to between 35 and 50. Use the Preview window to examine the filter effects and change the Radius or Threshold setting to optimize the result. Then, click OK.

As you'll notice, the filter creates white lines on a black background. See figure 2. To set the image to black lines on a white background, choose Image, Adjust, Invert.

To thicken each line to achieve an effect much like a wood block stamp, choose Filter, Other, Minimum. Then, you enter 2 or 3 in the text field and click OK. See figure 3.

Creating a Colored Pencil Sketch

This tip builds on the previous tip, Convert An Image To A Line Drawing. First, open your image and duplicate the background layer. To do so, drag the background layer to the New Layer icon in the layers. Then, select the new layer and use the Smart Blur filter to create a line drawing of the layer image.

As you may recall, the Line Drawing tip directs you to choose Filter, Blur, Smart Blur and set Quality to High and Mode to Edge Only. Then, using the Preview window to view the filter effects, you adjust the Radius and Threshold settings. Finally, you click OK and invert the image.

Next, you need to posterize the colors of the background layer image. Select the background layer and choose Image, Adjust, and Posterize. In the resulting dialog box, enter 4 in the text field and click OK.

Finally, select the line drawing layer and choose Multiply from the Mode list box in the Layers palette. As you can see, Multiply removes the whites and overlays the line drawing on the posterized image, creating an effect very similar to a colored pencil drawing. See figure 4.

Changing an Object's Color in Photoshop with Selective Color

If you want to change an object's color, Photoshop gives a command called Selective Color, which will do so fairly painlessly. To use Selective Color, choose Image > Adjust > Selective Color. In the resulting dialog box, select the color you wish to change in the Colors pop-up menu at the top of the dialog box and then use the CMYK sliders to tweak the color. Modifying the selected color only affects the color you specify; no other primary colors will change.

For instance, if you select the Greens option in the Colors pop-up menu and then significantly decrease cyan, only the cyan in the green component of the image will be affected.

Cleaning Up a Washed-Out Image

Washed-out, bland images usually entail a great deal of production time attempting to correct the image's tonal range. However, before you try to correct a washed-out image through complex contrast and tonal adjustments, try the following quick technique.

Choose Windows, Show Layers to activate the Layers palette. Then create a duplicate of the Background layer. To do so, select the Background layer and drag it to the New Layer icon. Now, set the Mode option of the new layer to Overlay. As you may know, Overlay mode increases contrasts but preserves highlights and shadows.

Pseudo-color in Photoshop

Indexed color isn't just for the Web. You can use it to transform a grayscale image into a pseudo-color image by creating a color table based on the image and then changing the colors in the table. To try this out, convert a grayscale image to indexed color by choosing Image > Mode > Indexed Color. Next, access the image's color table by choosing Image > Mode > Color Table. Once the dialog box appears, click in the color swatch at the upper left-hand corner of the table and drag to the swatch at the lower-right corner. As soon as you release the mouse, the Color Picker will appear allowing you to pick the first of the colors for your two-color blend. Select a color and click OK. The Color Picker will appear again immediately. Select your second color and click OK. Your color table now contains swatches of the various blend steps. If you're happy with the blend color scheme, click OK and the new color scheme will be applied to the image instantly.

Cropping Out That Pesky Edge

Many times an image will have one or two pixels along an edge that must be cropped out. Instead of using the sometimes-clumsy Crop tool to create a crop selection and laboriously resizing the selection to exclude the unwanted pixel edge, try this quick fix.

Choose Select, All to select the image. Then press the arrow key to move the selection one pixel over to exclude the pixel edge. Next, choose Image, Crop to crop out the edge.

Creating Triangles with Photoshop 5

If you ever need to create a triangle in Photoshop, you can do so by utilizing the Arrowheads function of the Line tool. To try this, select the Line tool, and then set its options. You'll need to specify a line width close to how large you want your triangle to be. So, enter 36 pixels in the Weight text box. Then, select the Anti-aliased and End check boxes to position your arrowhead at the end of the line.

Now, click the Shape button and enter proportional Width and Length values. Vary these settings to create equilateral or isosceles style triangles. Leave the Concavity setting at 0, since you'll want a flat edge. Click OK and then click in your document. Hold down the [shift] key to constrain the triangle to a straight line. Drag upward until the bottom edge of the line corresponds to the edge of the triangle.