A Shadow from Glass
The marble in the "marble and matches" image requires additional effects for its shadow. The marble is made of transparent blue glass that allows light to pass through it. The density of the material, however, holds back some transference of the light. The color of the marble also affects the color of its shadow.
The main shadow is first. Using the Elliptical Marquee tool, on a new layer, I drew an oval with a slight feather to soften the edges (Figure 4.43). It was filled with a dark blue color.
Figure 4.43. In a new layer, an oval is selected with a slight feather to the edges.
The other objects in this painting are opaque. They block light, and therefore, they cast neutral shadows. In creating them, I used a black fill. The marble, however, is partially transparent. It allows some blue light to pass through it, which alters the color of the shadow. That is why the dark blue fill is needed.
The blue haze caused by the refracted light is created next. I created a narrower oval in the area of the marble's shadow and saved it into an alpha channel (Figure 4.44). Next, I created another narrower oval, which I saved into a second alpha channel (Figure 4.45). Then, the oval is heavily blurred (Figure 4.46). Using the Calculations command, the blurred channel is then subtracted from the original alpha channel, as shown in Figure 4.47. This gives a mask, which is saved into a third alpha channel to increase the softness of the effect at the center of the oval (Figure 4.48). This mask channel is then blurred again to soften the overall effect, as shown in Figure 4.49.
Figure 4.44. A narrow oval is selected in the area of the marble's shadow.
Figure 4.45. The selected oval is saved as a selection into an alpha channel, and then it is blurred.
Figure 4.46. Another narrower oval is created, saved to an alpha channel, and then heavily blurred.
Figure 4.47. Using the Calculations command, the narrowest, heavily blurred channel is subtracted from the original, narrow alpha channel. The results are sent to a new channel.
Figure 4.48. The Calculations command result gives a mask that increases the softness of the effect at the center of the oval.
Figure 4.49. The final channel is then blurred to soften the overall effect.
In the RGB channels, a new layer is created. The mask channel is loaded as a selection and filled with a blue color that is lighter than the previously used one (Figure 4.50). This superimposes a light blue highlight on the shadow underneath it.
Figure 4.50. The channel is converted into a selection and filled with a blue color that is lighter than the one previously used to create the shadow.
As a final touch, the highlights visible within the shadow are created with a soft-edged paintbrush, which uses various shades of light blue and white.
Figure 4.51 . The highlights visible within the shadow are created with the Airbrush tool, which uses various shades of light blue and white.
Another example of light that travels through transparent objects is reflected in the image named ointment (Figure 4.52). In this image, the shadow of the glass applicator runs across the cork (Figure 4.53). The applicator is made of clear glass, so colorization of the shadow is not necessary.
Figure 4.52. This picture shows another example of light that travels through transparent objects. Here, the shadow of the glass applicator runs across the cork.
Figure 4.53. This close-up shows the shadow that is cast over the cork.
In this case, the applicator acts as a magnifying glass that concentrates the light in a bright streak.
To create this effect, I employed the Paintbrush tool. I set the brush to fade out (run out of paint) at a specified time (Figure 4.54). In a new layer, a fade-out stroke is created using a yellow color. The fade distance is decreased and white is used to create a second streak. This completes the effect.
Figure 4.54. In the Brushes palette, I set the brush to Fade (run out of paint).
With the Shift key down, I clicked with the Paintbrush tool at the base where the highlight began and then again at the other end of the top of the cork following the direction of the shadow. The result was light shining through the glass applicator.
If you press the Shift key while using a tool, you achieve a straight line from click to click.