In programs of vector graphics circuits are main means of the description of images. In the raster program they have auxiliary value. Them use, for example, as vectorial masks for export of images with not square-topped cropping. Import of pictures from vectorial programs also can be produced in the form of circuits. One more application field — creation and storage of exact separation.

For operation with bitmap graphics the circuit is very convenient means. It is described not by a bit card, and only several formulas. On a disk this information occupies places very little. At all changes of the image the circuit does not break up to separate elements (points), and remains uniform object. Any transformations (reduction, magnification, turns, warps) a circuit do not worsen its quality. It is easy to select a circuit, for this purpose enough one click of the mouse. At last, quality of circuits does not depend on resolution and is always maximum.

It is necessary to understand a line consisting of sequence of segments as a circuit, each of which is described by the mathematical formula — a Bezier curve. The formula of this curve allows to define the form of a segment by means of coordinates of four points (fig. 6.1).

Nodes of a segment or anchor points (anchor points) set position of the beginning and the segment end. You can move a node, thus the segment form changes. 6.1 node And is selected for fig., and nodes In and With — are not present.

Two directing points (direction points) define length and position of guide lines (direction lines). Moving guides, you change the segment form, but thus guides are mandatory allocated on a tangent.

In the circuits created in program Photoshop, there are three types of nodes (fig. 6.2):

• The linear. Has no directing (fig. 6.2,). Circuits are formed Of such points with rectilinear segments.
• The smooth. Its guides are allocated on a straight line (fig. 6.2,). Moving one of guides, you influence and the second, i.e. change the form at once two segments converging in a node.
• The angular. Its guides can be allocated under the arbitrary corner (fig. 6.2,). At guide relocation the form only one segment which it defines changes.

And

For creation of circuits tools of two groups are used. The first of them is intended for creation of a circuit of the arbitrary form, the second — for creation of vectorial figures (closed circuits) to the given configuration.

Vectorial objects can be applied in the program in three modes:

• Normal circuits. These are the auxiliary objects existing in the document, but invisible. If a circuit to activate, it appears on the screen, and it can be outlined the paint tool or to fill with the arbitrary filling. On the basis of circuits there are selected areas.
• Planimetric layers-masks. These are vectorial masks of layers. As well as normal layers-masks, they hide a layer part. Depending on setting of the circuit making a mask, can be hidden or area in a circuit, or out of it.
• Planimetric layers. The layers of special type consisting of filling and circuits, playing a mask role.

Let's note that vectorial objects in all three cases are absolutely identical. However, how they are used (as a planimetric layer, a planimetric mask, a normal circuit) their influence on the image, properties, application field and display methods in the program changes. Before explicitly to consider properties of circuits, we result examples for each mode of their usage.

1. Open any document, for example Things.jpg. Clarify the image in the document so that created circuits were well visible.

2. Select tool Rectangle (Rectangle) intended for creation of rectangles. It is allocated together with other tools of creation of figures in separate group (fig. 1.5 see).

3. Three buttons in a property bar define a mode of creation of a figure (fig. 6.3). Clicking on button Create new shape layer (to Create a new planimetric layer) you pass in a mode of creation of a new planimetric layer. Button Create new work path (to Create a new working circuit) includes a mode of creation of a normal circuit. The third button Create Filled region (to Create area with filling) activates a creation mode растрированного object.

4. Select the first button. Pass in a document window. Push the mouse and drag the cursor, creating a circuit. Release the mouse button, and you see a rectangle with thin black обводкой, colored by working color (fig. 6.4).

5. Look in palette Layers (Layers). There was a new layer (fig. 6.4), its contents — continuous filling. The new layer has a mask consisting of a circuit of a rectangle. Everything that outside of a rectangle — is masked. The mask is connected to a layer.

6. Обводка a rectangle means that the planimetric mask is active. In a palette of layers activity is shown обводкой a mask tag. While in the document there is the active circuit-mask, new circuits at creation turn on in it.

7. Select tool Ellipse (Ellipse). Drag the cursor under the image, creating an ellipse. The received figure became a mask part. Individual circuits as a part of difficult vectorial object for clearness we will name subcircuits (fig. 6.5).

8. Cancel activity of a planimetric mask, clicking or on its tag in a palette of layers (обводка a tag disappears), or on the button with a tick in the right part of a property bar.

9. When the mask ceased to be active at creation of new objects you can select again their type (a new planimetric layer, a working circuit, растрированный object). Click on tool Rounded Rectangle (the Rounded rectangle). In a property bar set a level of a rounding off of corners of the future rectangle in the field of input Radius (Radius). Than more value of radius, corners are especially rounded.

10. Install mode Create New Shape Layer (to Create a new planimetric layer). In a property bar parameters of a new planimetric layer are set:

11. It is possible to define at once style, a superimposing mode, a transparency (fig. 6.7). Afterwards these attributes are easy for changing the same as and for a normal layer. Select the given parameters arbitrarily or leave them by default. Attributes at formation of a planimetric layer are in a property bar for all tools of group.

12. Create the rounded rectangle. The program organized a new planimetric layer. Now them in the document two (fig. 6.8). Pay attention that all parameters are set for a layer entirely, and only the rounding off of corners can be defined separately for each received object. Create rectangles with a different rounding off.

Let's test also other tools of group. All of them have three modes of creation (pay attention that the mode can be defined, only if in the document there is no the active circuit). Each of tools we will build new subcircuits within the active planimetric layer (fig. 6.9).

1. Select tool Polygon (Polygon). Its unique attribute is the number of the sides set in the field of input Sides (Number of the sides). Construct polygons with different number of the sides.

2. Pass to tool Line (Line). Install width of a line in the field of input Width (Width). Place the tool on the image, push the mouse button and drag the cursor. Behind it the thin rectangle with обводкой is pulled — a line which width corresponds to value in the field of input Width (Width), and its length and position you define. To finish line creation, release the mouse button.

3. One more tool of group — Custom Shape (the Arbitrary figure). With its help draw circuits of figures of the given form. Select this tool. Dragging the cursor, create a figure shown on a tag of the tool.

4. You can install other type of a figure and other parameters. Uncovered list Shape (Figure) in a property bar has the same control items, as the list of paintbrushes. Select from the list one of figures (fig. 6.10). The tool tag changes accordingly. Construct a new figure. Click on an arrow to the right of a tool tag in a property bar opens a window of additional parameters (fig. 6.11). Changing them, you can create figures with the defined height or width, a ratio of the sizes, and also to build a figure from center.

As the planimetric layer is not only a layer, but also vectorial object, it is displayed in special palette Paths (Circuits). In it the information on all circuits of the image contains.

1. Open palette Paths (Circuits). Now in a palette single line (fig. 6.12,). In it the planimetric mask of a current layer is shown. If the mask is active, the line is highlit. You can activate a planimetric mask in the image, clicking on its line in palette Paths (Circuits).

2. Pass to other planimetric layer. Now in palette Paths (Circuits) its mask (fig. 6.12,) is shown. Thus, in a palette of circuits the current planimetric mask is displayed only.