Copyright: Copyright © 1998-2001 Ability Plus Software (UK) Ltd.


Vector tools

Please note that vector tools are not available in the "standard" version of Ability Photopaint. Please see http://www.ability.com/ for more information.

Most Photopaint images, whether scanned or created from scratch, are laid out much like any other image, for example, photographs and paintings. Basically there is a surface with an arrangement of colors, represented in Photopaint by combinations of pixels. Whenever you want to edit the image you have to use various techniques to change selected pixels within the whole image. In effect this is what happens whenever you use the normal paint tools to add or remove color, and the selection tools to concentrate on a limited area of the image which you may want to edit, move, scale, or transform in some other way. All of these techniques are relatively cumbersome and inexact, in that it is sometimes difficult to select precisely the area you want to edit. With vector tools you can create areas of color which are treated as objects in their own right. Although these objects are part of the image, in that they are “superimposed” on it, they can also be regarded as independent of the image, therefore easily editable in a variety of ways.

The Photopaint Vector tools use what are called vector paths to create vector objects. Each vector object has a sharply defined shape which encloses a color or range of colors. Vector objects are treated independently of other vector objects and of any image created through normal bitmap technology. Essentially a vector object can be understood as a set of coordinates with various attached attributes. The advantage in using vector objects is that they are easy to manipulate, and therefore easy to scale, move, rotate, etc. as whole objects. None of these operations is easily accomplished with normal bitmap images.

Whenever you create a vector object it is not added to an existing layer but placed above all the layers. If the object is 100% opaque you will not be able to see through to the images on the layers below. However, it is easy to edit any object so that it is transparent in some degree.

The following sections will show you how to create and edit vector objects.

Creating a vector object

Editing vector objects


Creating a vector object

Once you have read about vector objects (see Vector tools) it is a simple step to creating your own.

First, you need to open up the Vector tools box by clicking on the Vector tool [image] on the Tools bar (this is paired with and next to the Vector Preview Mode [image] ). The Vector Tools Box is displayed with all the tools necessary to create and edit vector objects.

There are various options for creating objects:

Vector Line

Vector Rectangle

Vector Round Rectangle

Vector Oval

Vector Polygon

Bezier Curve

Vector Free Hand Objects

Vector Text


Vector Line

Click on the Vector Line tool [image] in the Vector tools box.

Drag the pointer till the line is the required length and then release the mouse.

The line will be given the color of the current background color.

You can read about how to edit vector objects in Vector objects: Modifying.

See also:

Creating a vector object

Editing vector objects


Vector Rectangle

Click on Vector Rectangle [image] in the Vector tools box.

Drag the pointer vertically and horizontally till the rectangle is the required size and then release the mouse.

The rectangle will be filled in with the current foreground color.

You can read about how to edit vector objects in Vector objects: Modifying.

See also:

Creating a vector object

Editing vector objects


Vector Round Rectangle

Click on Vector Round Rectangle [image] in the Vector tools box.

A dialog box will be displayed. Use the Radius slider to change the “roundedness” of the corners. You can set any value between 0 and 50. A radius of 0 produces a normal rectangle.

Drag the pointer vertically and horizontally till the round-cornered rectangle is the required size and then release the mouse.

The rectangle will be filled in with the current foreground color.

You can read about how to edit vector objects in Vector objects: Modifying.

See also:

Creating a vector object

Editing vector objects


Vector Oval

Click on Vector Oval [image] in the Vector tools box.

Drag the pointer till the oval is the required size and then release the mouse.

The oval will be filled in with the current foreground color.

You can read about how to edit vector objects in Vector objects: Modifying.

See also:

Creating a vector object

Editing vector objects


Vector Polygon

Click on Vector Polygon [image] in the Vector tools box.

The “Polygon” dialog will be opened. You can create either a Polygon or a Star by clicking on the appropriate button. Set the number of sides for the polygon or radiating points for the star, between 3 and 16 inclusive, in the Number of Sides box.

In the case of the star you can use the slider to set the Attitude.

Drag the pointer till the polygon or star is the required size and then release the mouse.

The polygon or star will be drawn using the current background color. Only the outline will be drawn, with the body of the shape hollow.

You can read about how to edit vector objects in Vector objects: Modifying.

See also:

Creating a vector object

Editing vector objects


Bezier Curve

Bezier curves enable you create vector objects by using a series of curves, lines and control points to draw vector paths. Each point has an associated axis which can be used to increase the length and degree of curvature of a section of the vector path. The final shape of the vector object is created when you close off the curve. There are various ways of doing this, as you will see.

Click on Bezier Curve [image] in the Vector tools box.

There are two basic techniques to remember when using the mouse to draw curves and lines:

•	Curves: Click once and keep the mouse button depressed to create a curve point, marked by a control point. An axis centered on this point is displayed along with two handles, one at either end of the axis. Drag the handles to extend and rotate the axis, thereby changing the length of the curve and the degree of curvature. Release the mouse button to set the curve. After setting a curve, moving the pointer will create another curve until you click again.

•	Lines: Click once and release to create a control point. Move the pointer to draw a straight line, which becomes fixed as soon as you click again. After setting a line, moving the pointer will draw another line until you click again, at which point you can create a curve if you keep the mouse depressed (as described above) or another line if you click and release.

To complete a curve you must right-click to define the finish point and open a submenu with the following options:

•	Open Curve: draws the curve using the current background color without joining the start and finish points.

•	Smooth Closed Curve: draws and fills in the curve with the current foreground color, the start and finish points being joined together with a smooth curve.

•	Glue end points: draws and fills in the curve with the current foreground color, the start and finish points being pulled towards one another.

•	Close with line: draws and fills in the curve with the current foreground color, the start and finish points being joined with a straight line.

The best way to learn how to create vector objects using Bezier curves is, as always, to experiment. You can always edit or delete the results later on.

You can read about how to edit vector objects in Vector objects: Modifying.

See also:

Creating a vector object

Editing vector objects


Vector Free Hand Objects

This option enables you to draw vector objects freehand using your mouse.

Click on Vector Free Hand [image] in the Vector tools box.

Drag the mouse pointer to draw the required shape and then release the button. A submenu is displayed, giving you the choice of any of the following for completing the curve:

•	Open Curve: draws the curve using the current background color without joining the start and finish points.

•	Smooth Closed Curve: draws and fills in the curve with the current foreground color, the start and finish points being joined together with a smooth curve.

•	Glue end points: draws and fills in the curve with the current foreground color, the start and finish points being pulled towards one another.

•	Close with line: draws and fills in the curve with the current foreground color, the start and finish points being joined with a straight line.

You can read about how to edit vector objects in Vector objects: Modifying.

See also:

Creating a vector object

Editing vector objects


Vector Text

This option enables you to add vector text to an image, selecting from all the usual fonts, sizes and styles.

Click on Vector Text [image] in the Vector tools box.

The mouse pointer turns to a T-symbol. Move this to the point where you want the text to appear and click once to open up the “Vector Text” dialog.

In the main box of the dialog type your text.

All the usual font options for the text are available through the Font button. These include font type, style, and size. (Note that changing any of the font characteristics will affect the contents of the whole of the “Vector Text” dialog. If you would like to mix font characteristics in a piece of text, it is necessary to open up the dialog separately for each change.)

The text will take the color of the current Background Color box i.e. the lower box in the Tools bar.

In the Alignment box you can choose either Horizontal or Vertical for text to run either across or down the image window respectively.

There are two ways you may want to edit vector text:

•	firstly, treating it purely as text, you can select the Vector Text button [image] in the Vector tools box and click on the vector text you want to edit i.e. using the mouse pointer T-symbol. This opens up the “Vector Text” dialog again, with the relevant text selected. Edit the text as you would normally e.g. you can change the style, size and font, and remove or add letters. Click on OK to close the dialog box and apply your changes.

•	secondly, you may treat the vector text as both text and shape, as with any other vector object. In this case, you can use the normal procedures for editing vector objects, which you can read about in Vector objects: Modifying.

See also:

Creating a vector object

Editing vector objects


Editing vector objects

There are several ways in which you might want to edit the vector objects you have created (see Creating a vector object).

These fall into three categories:

•	Adjustment of the object’s size, position, shape and alignment.

•	Changing the color, transparency, border properties, etc. of the object.

•	Manipulating, adding and deleting control points to change the shape of the object.

Before you can proceed with editing you must select one or more of the vector objects. To do this click on the Select Curves tool [image] in the Vector tools box.

Various dialogs and tool boxes are displayed. (These will be dealt with later.)

Select one (or more) of the vector objects by dragging your mouse around the relevant object (or objects) and then releasing the mouse. Alternatively, move the cross pointer till it turns to a hand over the object and then click once. Since you will often have several objects in close proximity, or even overlapping, this latter method is a useful way of pinpointing the object to be selected. A box is placed round the object to indicate that it has been selected. You can now edit proceed to edit the selected object in various ways.

For information on how to edit an object’s size, position and shape, see Vector objects: size, position, shape.

For information on how to alter color properties, see Vector objects: Fill options.

For information on how to manipulate control points to alter the shape of the object, see Vector objects: Modifying.


Vector objects: size, position, shape

Once you have selected a vector object (see Editing vector objects), you can make changes to its size, position and shape. This is achieved by making adjustments to the transformation box which has been placed around the object.

The Vector tools box contains the following options, which are accessible by clicking on the relevant tool:

Free transform [image]. This allows you to move, scale and rotate the object. The pointer becomes an arrow inside the box, a cross while placed over any of the handles, and a curved double-headed arrow outside the box.

•	To move the object, place the pointer inside the box and drag the arrow to a new position.

•	To stretch the object, place the pointer over the relevant handle (or handles) and drag the cross to a new position.

•	To rotate the object, move the pointer anywhere outside the box and drag-rotate the curved double-headed arrow to a new position. Note that the object rotates about the star-like symbol at the center of the box. You can move this symbol by clicking on it and dragging. The object will henceforth rotate about the new position.

The above operations are together known as Free Transforms, that is they are applied by you by hand, using the mouse, and are all available simultaneously. You can restrict the range of transforms to any one of these or to one of the other options. In choosing one of these options, you automatically make the others unavailable. For instance, while scaling you will be unable to rotate the selection.

To access the other options click on the relevant tool or right-click and make a selection from the displayed menu.

The options include:

Scale		Stretch the object either horizontally or vertically by dragging the handles of the transformation box. The object will be scaled to match the new box dimensions.
Rotate		Rotate the object by dragging the double-headed arrow outside the transformation box. The object will rotate with the box. Note that the star-like symbol acts as the center of rotation and can be dragged to a new position.
Skew		Skew the object by dragging a center-of-line handle in either direction along the line of the transformation box on which it is situated. The object will adjust to fit the skewed box. Note that dragging a center-of-line handle moves the whole of the line.
Move		Move the object by dragging the transformation box to a new position.
Mirror		Mirrors the object when the transformation box is dragged to an adjacent position: left or right, the object is reflected in a vertical “mirror”; up or down, the object is reflected horizontally; diagonally, the object is reflected vertically and horizontally. Note that Mirror moves the object to its mirror-image position.
Reset		Resets the original position, size and shape of the object i.e. returns it to its state when first selected. Note that Reset is available only through the right-click menu and not the tool box.

In addition to the above you also have the option to align vector objects in a variety of ways: see Vector objects: aligning.


Vector objects: aligning

The Align tool box gives you the power to arrange objects in a variety of ways.

Since vector objects can overlap in the image window, it is useful to be able to decide which position each object will occupy in relation to the others in the “hierarchy”, and therefore which objects will be completely visible and which partially hidden. In addition, Align gives you options for adjusting the height, width and position of selected groups of objects.

If you have two or more overlapping objects, you may want to change the order of one or more of the objects. Select the object you would like to re-align. It is best to use the hand-pointer and then click once (see Editing vector objects). For these tools to become active you must select one and only one object (with the exception of grouped objects - see below).

In the Align tool box there are four options highlighted:

Bring to Front		The selected object will be brought in front of all the objects it overlaps.
Send to Back		The selected object will be sent to the back of all the objects it overlaps.
Bring Forward		The selected object will be brought in front of the overlapping object one place ahead.
Send Backward		The selected object will be sent behind the overlapping object one place behind.
The above options work with a single selected object. However, you can select several objects and then turn them into a single Group. The boxes surrounding the individual objects are turned into one big box around all the selected objects. To create a group drag the pointer round the relevant objects and then release. The individually selected objects can now be turned into a group by clicking on the G tool [image]. The above four options are highlighted. You can now proceed to move the group to the front or back, forwards or backwards. To Ungroup and return to the individually selected objects, just click on the U tool [image].

To activate the rest of the align tools you need to select at least two of the objects. Drag the pointer round the objects you want to align and then release the mouse button. Each of the objects is surrounded by its own box. Note that if you attempt to move one of these objects they will all move together.

After you have made your selection the rest of the options in the Align tool box become available. Each of the following commands applies to the currently selected objects (non-selected objects are ignored):

Align Left		Objects are lined up with the object furthest to the left.
Align Right		Objects are lined up with the object furthest to the right.
Align Top		Objects are lined up with the top of the current highest object.
Align Bottom		Objects are lined up with the bottom of the current lowest object.
Align Vertical		Objects are lined up along a vertical axis.
Align Horizontal		Objects are lined up along a horizontal axis.
Space Evenly Vertically		Spaces three or more objects evenly in vertical direction.
Space Evenly Horizontally		Spaces three or more objects evenly in horizontal direction.
Make all same width		Makes all objects the same width.
Make all same height		Makes all objects the same height.
Make all same size		Makes all objects the same height and width.


Vector objects: Modifying

In normal viewing mode vector objects are displayed as colored shapes, curves or lines. As explained in Editing vector objects it is possible to do basic editing when still in this mode. However, for more sophisticated editing of an object’s shape it is best to go into Preview mode. The objects then appear in their basic outline without color, that is as vector paths, and the main control points can be seen.

The control points mark the key places along the vector path and are used for altering the shape of the vector object. This is done by manipulating the axis that runs through each control point.

The following section shows you how to modify various types of vector object, for example, a Vector Rectangle and a Bezier Curve.

To modify a vector object two actions must be performed beforehand:

Click on the Modify tool [image] on the Vector tools bar. This displays the Modify Tools Bar, which contains these tools:

 Modify Control Points

 Sharp Corners

 Add Control Point

 Remove Control Point

Next, click on the Preview mode tool [image] on the Tools bar. The vector objects are then displayed as vector paths.

Make the control points visible by clicking on the Modify Control Points tool [image] on the Modify Tools Bar and then clicking on the vector object you would like to modify. There will be four control points, one at each corner, for a rectangle; two for an oval, one at the top and one at the bottom; one for each “joint” in a Bezier Curve, that is, at each of the points where you clicked when creating the curve; and so on.

Notes on control points and axes

1.	Each control point (except for those described in 7 below) has an axis running through it in a particular direction (sometimes the axis is not visible i.e. when the control point is at a corner the axis is folded up). The axis is centered on the control point, with the two halves being equal in length.

2.	At either end of the axis there is a handle. Handles are used to turn the axis around the control point, which acts as the center of rotation, and to alter the length of the axis. Changing the direction or length of an axis changes the vector path that runs through the relevant control point. Note that the axis through a control point situated on a curve of the vector path is always at a tangent to the vector path at that control point (if the path at that point is a corner the axis is folded up, and if it is a straight line the axis runs along the line).

3.	As a line is lengthened the vector path around the control point is stretched into a wider curve; as it is shortened the vector path is contracted until it finally becomes a sharp corner when the line is of zero length (as with a square).

4.	Whatever you do with one handle is mirrored by the other handle, that is, the handles act in opposing ways - turning one handle downwards will tilt the opposite handle upwards, dragging one handle outwards will cause the other handle to move an equal distance in the opposite direction, and so on.

5.	The handles can be moved or rotated by dragging with the mouse. Note that you can also drag the control point itself and the line will move as a whole without altering its length or direction.

6.	Alterations in the vector path are restricted to the sections between the adjacent control points on either side of the control point that is being edited.

7.	Some vector objects – especially those that are “open curves”, or polygons without a fill color – have start and finish points that “float free”. These do not have the normal control point and axis, but either a point without an axis or a one-length axis i.e. there is no mirror axis acting in an opposed way.

Apart from modifying vector objects by dragging control points and handles, you can also add and remove points and turn curves into sharp corners:

•	Since the vector path is only affected between adjacent control points on either side of the edited control point, you may wish to add or remove control points to restrict or increase the editable range. To add a control point click on the Add Control point tool [image] on the Modify Tools Bar. Next, click on the relevant vector object to active all the current control points. Move the mouse pointer over the point on the vector path where you want the new control point to appear and click once. A control point and axis will be added to the path at this point. The segment of vector path that is affected when editing will thus be reduced. The new control point can be used to alter the vector object, as described in the previous paragraph.

•	Contrariwise, if you would like to remove a control point, click on Remove Control point [image] on the Modify Tools Bar and then click on the relevant vector object. Next, click once on the control point you would like to remove. The control point will disappear and the segment of vector path that is affected when editing will thus be increased.

Note that after adding or removing a control point you must once again click on the Modify Control point tool [image] and then the vector object to be able to modify the vector path, as described above.

•	The Sharp Corners tool [image] enables you to convert a control point on a curved vector path into a sharp corner. The axis running through the control point will be reduced to zero length, although you can stretch it out again by dragging in the usual way (the sharp corner will then become a curve again). Convert a control point into a sharp corner by clicking on the Sharp Corners tool and then clicking on the relevant object to activate the control points. Next, click on the control point you would like to convert to a sharp corner.

When you have modified the vector objects to your satisfaction, click on the Preview mode tool [image] on the Tools bar again to switch it off and return to the normal vector object view, with colors restored.


Vector objects: Fill options

Vector objects can be filled in with color, using either Solid Fill, Gradient Fill or Pattern Fill.

To make these available you must first click on Select Curves [image] in the Vector tools box. Next, you need to use your mouse to select one of the objects (see Editing vector objects). The Fill tools box and Bezier Options boxes are displayed (as well as the Align box - see Vector objects: aligning).

Choose from these options:

Vector objects: Solid Fill

Vector objects: Gradient Fill

Vector objects: Pattern Fill


Vector objects: Solid Fill

You can fill a vector object with a solid color by clicking on Solid Fill [image] in the Fill tools box (see Vector objects: Fill options).

Before clicking on Solid Fill you need to select a vector object. The “Fill” dialog is then displayed:

In the Color box select the Fill color from:

•	Foreground: the current foreground color

•	Background: the current background color

•	Black: solid black

•	50% Gray: half white, half black

•	White: solid white

•	Custom Color: select a color in the Select Color dialog

Note that the Fill color is displayed in the Preview box.

In the Blending box set the Mode and Opacity. The Mode works in a similar manner to blending between layers, except that blending is restricted to the selected vector object, rather than applied to the whole vector object “layer” (see Vector objects: blend modes).

Once you have set the Color, Opacity and Mode click on OK to apply the Fill.

The particular Solid Fill applied will now appear in the Bezier Options box. Here you can edit the Fill in a number of ways:

1.	First, click on one of the Solid Fills listed in the top box. (Since you can set many of these for the same object, there may be more than one listed. For each of them the relevant details will be displayed in the rest of the box.)

2.	In the Border Size box you can set a border value between 0 and 50.

3.	Click on the Border Color box to open up the Select Color dialog to select a new color.

4.	In the Mode box select a mode from the drop-down list (see Vector objects: blend modes).

5.	Use the Opacity slider to set a value between 0 and 100%.

6.	Finally, click on the Fill Color box to open up the Select Color dialog, where you can select another color.

The changes you make will take effect immediately.

At the top of the box there are some Move buttons. These allow you to move through the saved Solid Fills:

 Move operation up

 Move operation down

 Move operation first

 Move operation last

As you click on these you will see the selected object change to display the properties of each of the chosen Solid Fills. If you would like to delete a particular Solid Fill, make sure it is selected and then click on Delete operation [image]. The Solid Fill will be deleted from the list and the next one down in the list applied to the selected vector object.

You can create many Solid Fills for the one vector object, as well as Gradient Fills and Pattern Fills.


Vector objects: Gradient Fill

You can fill a vector object with a gradient by first selecting a vector object and then clicking on the Gradient Fill [image] tool in the Fill tools box (see Vector objects: Fill options). The Bezier Options box is then displayed.

To activate the Gradient Fill options in the Bezier Options box, you must first drag the gradient pointer – a hand symbol – a short distance across the selected vector object. Release the mouse and the Gradient Fill option is listed in the box at the top of the Bezier Options box.

Select Gradient Fill to make the normal gradient options visible. You can now proceed to set the Border Size and Border Color, and the Mode and Opacity (see Vector objects: blend modes).

Next, select from the available gradients in the Gradient box and gradient types in the Gradient type box below. For information on using gradients and some examples, see Gradient Fill. However, bear in mind that in this case you are using gradient fill with vector objects and not with normal selections or layers.

Any selections you make in the Gradient and Gradient type boxes, as well as in the Border Size and Color and Mode and Opacity boxes, are immediately implemented in the selected vector object.

Note that the extent of the gradient is in accordance with the distance you initially dragged the gradient pointer. You can alter this by making all your gradient selections, as described above, and then clicking on the Set Vector button at the foot of the box. This turns the pointer to the gradient hand-pointer again: drag this the required distance across the vector object and then release the mouse. The gradient is applied across this distance.

Note that every gradient you use with this particular object is listed in the box at the top of the dialog, along with any Solid Fills and Pattern Fills you may have created.


Vector objects: Pattern Fill

You can fill a vector object with a pattern.

1.	First select a vector object and then click on Pattern Fill [image] in the Fill tool box (see Vector objects: Fill options).

2.	The pointer becomes a paint tin. Move this over the selected object and click once.

3.	In the first instance the object will be filled with a gray color. However, a Pattern Fill option will now appear in the Bezier Options box. Click on this option to display the rest of the Pattern Fill options.

4.	Drag the slider to change the Border Size of the object.

5.	Change the color of the border by clicking on the Border Color box to open up Select Color.

6.	Set the blend mode of the object in Mode and the degree of transparency in Opacity (see Vector objects: blend modes).

7.	To fill the vector object with a pattern, do the following:

a.	Click anywhere in the Fill Pattern box. This opens up the Pattern Editor.

b.	In the Pattern Editor you will find a display of all the patterns you have previously saved. (If the Pattern Editor is empty you need to create a pattern before you can proceed. Do this by making a selection of the part of an image that contains the pattern you want to use, and then select Make Pattern from the Select menu. The selected pattern is then made available to all tools that use patterns.)

8.	Click on the pattern you want to use and click OK.

The selected vector object will be filled in with the chosen pattern. To change the pattern fill for the object just select another pattern. You can have many pattern fills attached to the same vector object.


Vector objects: blend modes

The following examples show you how to apply the blending techniques discussed in Vector objects: Fill options. Bear in mind that the whole point of blending is to be able to work out what color values will be displayed when an image is composite, that is, made up of various layers and objects, with some colors overlapping one another.

Blending with vector objects is similar to blending between layers, but with these differences:

•	All the vector objects belonging to an image can be regarded as occupying a layer of their own. This layer is positioned above all the normal image layers.

•	The effect of blending with vector objects is worked out by taking the color of the selected vector object, along with its mode and opacity, and calculating a final color from a combination of this, the color of the underlying image layer, and the color of any other vector objects that overlap with the selected object.

Photopaint has to calculate, for each pixel, the resultant color from a combination of the base color (the color of the layer below the vector object “layer” or the color of the object that overlaps with the selected object) and the blend color (the color of the selected vector object). The particular blend mode used determines, of course, the way the resultant color is calculated.

The default value for the blend mode is Normal, as you can see in the Mode box.

Another important concept when selecting a blend mode is that of opacity, which is set in the Opacity box. For some blend modes an effect becomes apparent only if the opacity is set at less than 100% e.g. Dissolve.

The main blend options, which you can select in the Mode box, are:

•	Normal

The resultant color is the same as in the currently selected object (subject to the amount of transparency set in the Opacity box, therefore visibility through to the lower layer). In effect, the base color is not used to help calculate the resultant color where the base and blend colors overlap.

•	Dissolve

An object with less than 100% opacity is converted - “dissolved” - to 100% opaque randomly scattered pixels. The effect is of a rough brushstroke, containing a mixture of blend and base pixels, rather than an evenly transparent one.

•	Multipy

The brightness values of the base and blend colors can be combined to create a darker tone. This is done by multiplying the two brightness values when they are expressed as fractions. For example, white has a brightness value of 255 (the maximum) and is represented as 255/255 or 1; black has a brightness value of 0 (the minimum) and is represented as 0/255 or 0. All other brightness values are represented as fractions between 0 and 1 e.g. 150 is represented as 150/255; 100 as 100/255. Therefore, using Multiply we get the result (100 * 150) / (255 * 255), which works out at 59/255. You can immediately see that the resultant brightness will always be lower than (or equal to) the brightness of either one of the multiplied fractions. This intuitively fits in with our experience of placing one transparent sheet on top of another, where the result is always darker.

Note that the above means that if the blend color is white, the resultant color is the same as the base color. If the base color is white, the resultant color is the same as the blend color. If either the base or the blend color is black, the resultant color is black. If the base color is transparent, the result of blending any color is black (since a transparent layer counts as 0, that is, the same as black).

•	Screen

This mode has the opposite effect to Multiply, combining the base and blend colors to create a lighter tone.

These are some of the more important options, but there are many others:

Behind, Overlay, Difference, Addition, Subtraction, Darken Only, Lighten Only, Hue, Saturation, Color, Luminosity, Divide, Color Burn, Color Dodge, Hard Light, Soft Light

Remember that you can always cancel or change the effect of a blend mode by selecting another one, especially the Normal blend mode.

If you would like to make the blending operations using vector objects permanent, then you should select Flatten Image from the Layers menu. See the relevant notes in Merge operations with layers for more information.


Plug-ins

Please note that Plug-ins not available in the "standard" version of Ability Photopaint. Please see http://www.ability.com/ for more information.

A powerful feature of Photopaint is the ability to use "plug-ins". A plug-in is a mini-program that extends the operation of a parent program. To be used with Photopaint, the plug-in must be Adobe Photoshop™ compatible. A plug-in usually behaves in a similar way to a built-in filter.

Many design studios and freelance designers make their plug-ins available on the web. Although you will have to pay a fee to download some of these, there is still a huge number that you can download for free. Since most plug-ins are written to be compatible with Adobe Photoshop, you can begin your web search for suitable plug-ins by searching for something like: Photoshop plug-ins. Plug-ins are also available from time-to-time with computer magazines.

Installing and running plug-ins

1.	Follow the instructions that come with the plug-in. Usually, this will simply be a case of unzipping a compressed file into the correct target folder. Sometimes, the plug-in will come with its own setup program. In all cases, make sure the plug-in is installed in the Photopaint plug-in folder, which is typically:

\Program Files\Ability Office 2002\Plug-ins

In Photopaint, select Options from the Tools menu and view the General tab of the dialog to check and set the plug-in folder.

2.	Exit Photopaint and then restart it to activate the plug-in.

3.	To run the plug-in, make a selection on the current image (or select all of the image) and select Plug-ins from the Filter menu. A sub-menu is displayed showing all the available plug-ins.

4.	Pick a plug-in. Depending on the plug-in, either it will be applied immediately to the open image in your window or a filter dialog box will open. In the latter case you will be able to edit the settings for the filter. There will usually be a preview box to display the results before you apply the filter.

Note that some of the plug-ins act as true filters, that is they alter an image on the basis of those colors that comprise the image. However, there are plug-ins which overwrite the current image.