How should I shade a picture


For everyone at ease, let's first show a quick way to create shadows. The result usually has to be refined by hand.

Shadows, fast and dirty

1. The basic material for a shadow is provided by the object itself, which is to cast it. First you have to narrow it down by making a selection (see picture on the right). A mask, the path tool or a color channel can be used for this. The previous lessons already presented when which method is suitable. It is pleasant that the selection does not need to be very precise.

2. In order to be able to edit the shadow separately, a new layer must first be created (in Gimp for example with "Layer - New Layer"). The selection you have just made can be filled with the paint bucket from the tool palette. A silhouette has already been created. The shadow should lie under the candlestick. Therefore you drag the new layer with the mouse under the one with the object.

3. The black double should lie flat on the floor. To do this, you pull and pluck it with a distortion tool. In Photoshop it can be found under "Edit - Transform - Distort", in Gimp there is a corresponding button in the tool palette. When using it, your own visual experience is particularly important - as mentioned, the method is very unclean.

4. A trick for a natural effect is to adapt the shadow to an irregular surface. In preparation, a copy of this background must first be made, for example using "Image - duplicate". These are converted to gray levels and saved in any location. Everything is now ready to call up the “Distortion filter - offset” filter in Photoshop (Gimp: “Filter - Mapping - Bumpmap”).

Photoshop then requires the black and white original, the dark areas of which are evaluated as depressions and the light parts as heights. The shadow is reshaped accordingly. The black and white template should be open in Gimp. You can then select it from a drop-down list at the top of the window. After clicking "OK", the shadow has adapted to the background.

As a final step, the shadow becomes more transparent and has a soft outline. The transparency can be set with a slider in the layer palette, for example to 80 percent. Then you can use the Gaussian soft focus filter to smooth out the edges.

Hand made shadows

This lesson assumes a single source of light, such as the sun. It cannot always be seen in a photo, so there are two scenarios:

Existing shadows refer to the location or the light source. The course of the artificial shadow can be precisely determined with their help, for which a few auxiliary lines are sufficient.

You can only guess the location because there are no clues. In this case, it should be marked as plausibly as possible based on your own visual experience. The only important thing then is that it is binding for all assembly elements.
Shadows usually come on their own level. You paint them on with the brush tool and black paint. Then the Gaussian blur gives them smooth outlines, and the layer's Opacity slider makes them transparent. You may also want to use the "Distortion filter - offset" (Photoshop) or "Map - deform" (Gimp) filter to adapt them to an uneven surface. The filter was introduced in the previous lesson.

One rule is extremely important: As a rule, the values ​​for opacity and soft focus should be used consistently throughout the entire installation. It looks very unprofessional if the shadows are contoured differently or opaque.

The most important construction options are to be played through below:

The sun is to the side of the viewer

1. The simplest case: The sun is to the side of the virtual observer. For example, their rays hit the ground at an angle of 40 degrees. In the screenshot above, they can be seen as a red diagonal drawn in a separate layer. The light source itself cannot be seen.
If the sun is visible in the photo, you can simply draw a line that starts from it, touches the top of the obelisk, and then hits the ground.

If the sun is not in the photo, you can also determine a single angle for the complete assembly, according to which all shadows are directed. A line can be drawn from the top of the obelisk that corresponds to this angle. To determine it, the measuring tool, which can be found in the tool palette, helps again. The shadow ends at the intersection of the two legs, which are formed from the floor line and the angle. With Gimp it is good to know that you can set an auxiliary line there by pressing the Alt key and clicking the mouse.

The shadow can be drawn in quite easily by hand. In the present case, only a tapering triangle had to be painted in black. If the outlines are more complicated, you can draw in several angles that go, for example, over the roof ridge, the rain gutter and the dormer window. The method presented at the beginning is also an alternative. However, the silhouette usually has to be reworked.

2. In this variant there is a wall behind the obelisk. But this hardly complicates the matter. A vertical auxiliary line is drawn where the floor line and the wall base meet. The shadow follows her until the angle cuts it off.

3. Another variant: The shadow of a door falls on a wall. Where the shadow touches its lower edge, a vertical line cuts the shadow. It also serves as a fixed point for the shadow line that emanates from the upper edge of the door.

4. Shadows also tend towards the common vanishing point of an object. Therefore you can save yourself work if you want to draw shadows for a coherent construction.

The sun is in front of or behind him

1. Starting from the sun, draw a vertical line. Where it intersects the horizon line, there is an important fixed point: all shadow lines run towards it. As usual, they are limited by the angle of incidence of the sun.

2. For this construction you have to lower the sun below the horizon in order to carry out the construction. Otherwise everything goes as before: The vertical lines are drawn from the sun to the horizon. All shadow lines strive towards the intersection.

The sun is offset from the viewer

Here again three scenarios are conceivable:

1. The position of the light source can be seen in the photo. The procedures are as before.

2. The sun is not visible, but some objects that cast shadows. Further assembly objects are aligned with their alignment lines.

3. You want to set the position of the sun precisely. The tricky process can be used by subscribers in PHOTO HITS 9/2010 to read.