This month we will revisit parts of Satori and tease out more painting power that you might otherwise miss. We’ll begin with some new tricks with masks and layers.

Satori’s introductory guide has a chapter on rotoscoping, involving an animated jester. Sadly you cannot complete the exercise given there, because it refers to features in version 2 of Satori. In v1.63, published on the December SuperCD, rotoscoping had yet to be implemented.

Nevertheless, that exercise, in which a glow is added to a complex animated figure, contains a useful lesson in masking that can be applied elsewhere. Fire up your copy of Satori and follow me through this tutorial.

THE COLOUR CUBE

If you’re wondering about the function of the hexagons in the Colour dialog, it’s really quite straightforward. They are two views of cube. One corner is black and the diagonally opposite corner is white. You can see the black and white corners at the centre of the views.

Three of the other six corners are the primary colours red, green and blue. The rest of the cube shows all possible mixes of the primaries. All intensities of a hue fall in a line from black to white.

One way to pick a colour is to click anywhere on the cube. Slide the pointer around with the mouse button held down to see the currently selected colour change dynamically. To get a finer display of the graduation between two tints and black/white, go to the Mix tab. Choose a colour from the cube, and make a prolonged single click in one of the small squares at the corner of the mix tab.

The box will change colour, and the large rectangle will show the mix with the colour at the opposite corner. It’s a sub-section of part of the cube’s surfaces. You can now pick your painting colour by clicking in the mix, though sliding the mouse pointer does not show a dynamic change here. If you need a precise match with a colour in the image, click the eyedropper button and then on the place in the picture you want to sample.

This colour can then be transferred into the Mix tab as before, using a slow single click. A quick click will have the reverse effect – the colour at the mix corner will become the current colour selection.

A SHINING EXAMPLE

The demonstration in the guide has the figure being worked on in a file of its own, independent of the background. That will not be the case here, which is more realistic for a generally applicable technique.

Create a new canvas of modest size – 640 by 480 will do. If the background is not set to a dark colour such as black or deep blue, go the Canvas section and change it. This is not essential, but useful so you can easily see the effect you are about to create.

In the Geometry section use the Regular Polygon tool to draw a largish yellow star – see part 2 of the series if you don’t know how. Start the dragging operation at the place you want to be the centre of the shape. Now, twinkling is a bit beyond us, but we can add a halo of diffuse colour to make the star seemingly shine.

This involves turning the star shape into a mask and giving it blurred edges. The mask is applied to a background layer coloured with whatever hue we decide on for the glow, giving a blurred star. With the original star layer in front, the diffuse edges of the mask on the layer behind give the halo effect.

Click on New Layer and rename Layer 2 as Glow. Bring up the layer list and you will see Glow placed at the top and highlighted as the active layer, even though it’s invisible in the editing window because there is nothing on it yet.

Open the Colour window and choose a colour for the glow. You might like to choose something other than the limited range already in the palette. (The RGB sliders were explained in issue 135.) See the panel headed The colour cube for more information on colour selection options.

If you can’t hit on just the right colour, get as close as you can and click on the slider tab. You can now fine tune the hue by dragging the slider. I went for RGB values of 225, 220 and 0 respectively, to give a pale orange. When you’re happy, transfer this colour to the Layer Operations section of the layer tools by clicking in the box next to the Clear button.

Now set the glow layer to this colour by pushing Clear and selecting Coloured in the Clear Layer dialog. Satori now clears the layer by placing a coloured rectangle on it. Since Glow is in front of the layer containing the star, the entire image turns orange.

Next, through the use of a mask, you modify the rectangle so that only a blurred star shows. First, you must make a mask that exactly matches the star you drew earlier. Create a user mask on the Glow layer – this is done by clicking in the grey box on the right-hand side of the Glow entry in the layer list.

Click on Layer 1 in the layer list and then on Edit Shape in the Geometry section. The star is the only object on the layer, so it is selected by default. Now click on Copy and, in the next dialog, change the Copy Object To settings to Mask on Glow.

Now hit OK, and then Finish Edit. The star on Layer 1 has appeared through the orange because you’ve just made a copy of it on Glow’s mask layer, punching a hole through the rectangle. Note that, in the layer list, you can now see the star in Glow’s user mask.

The next step is to invert the mask so that the orange becomes transparent, and the transparent area becomes opaque. Click on the Invert User Mask button (lower right) in the Glow layer entry. The dark canvas background colour will re-appear, and the star will be obscured by orange.

Now select the Glow layer. In the geometry tools click the Rectangle icon on the far left. Press the Mask button. On the Effects tab click Blur. Wind the X and Y values up to 20. Any rectangle drawn now will be placed on to the mask layer and will blur any objects beneath it on the same layer.

Drag a rectangle over the star, and the shape becomes blurred. The fade-out starts within the star shape, so some yellow shows through at the edges and extends just beyond the shape, leaving some of the orange to linger on.

Take a moment to we examine the Object List window, in particular the mask for the Glow layer. At the bottom is the star. Above it is a rectangle placed there when you told Satori to invert the user mask.

The new rectangle switches the effect of the masking objects beneath it. Parts of the layer made transparent by the mask become solid again while previously solid areas become transparent.

Areas that were transparent because no object was present are unaffected by shapes in the mask. The top-most rectangle in the list is the blur region.

There’s one thing left to do: put this glowing orange star behind the original star, so that it haloes the edges. Drag Glow below Layer 1 in the layer list. Hey presto! – a yellow star surrounded by an orange glow.

MISSING THE POINT

You might be dissatisfied with the fact that the blur operation didn’t take in the points, only the edges, so that the glow doesn’t follow all of the shape.

It is possible to modify the mask. Select the Glow layer. Now, with painted objects, you can simply press Edit Shape in the Geometry tools, and pick an object for editing. That doesn’t seem to work with objects on the mask layer.

However, if you first click the Mask button, and then on Edit Shape, the objects selected are on the mask layer. Do this and click on Next to get the star polygon.

An alternative way to select this part of the mask is to bring up the object list, click on the regular polygon object in the Mask section of Glow layer, and then press Select for Edit.

Enlarge the star by dragging both inner and outer sets of nodes outwards. Then hit Finish Edit. The re-shaped mask will give a better effect, if still a little un-pointy.

Adding a glow to a complex shape is not an everyday requirement. Yet it illustrates two serious points: mastery of masks and layers is essential if you want to get anything worthwhile out of Satori, and there are more complex ways to manipulate masks than you will have appreciated at first.

SHADY DEALS

Adding text to a bitmap is simple enough, and in the first part of the series we saw how the mapping feature enables you to make text in to a window on a picture. Don’t forget that RIR and CVS files can be mapped, so you can create interesting fills in Satori.

This isn’t the sum total of what you can do with text in Satori, and it is worth exploring this further. It’s easy for text to lose impact because it doesn’t stand out from the background. There are several ways to remedy that.

A drop-shadow lifts text up from its background. If the gap between text and a black shadow is tiny, it puts the text into relief. A larger gap makes the words appear to float above the picture. Yet a pure black shadow looks crude and unrealistic in this situation. Satori makes light work of a number of more refined shadow effects.

Load any bitmap you have lying around. Go to Geometry and click on the text tool (the ‘T’ button). Enter some text on the Setup tab and choose a large and weighty font. Select a colour on the Colour tab, or pick a bitmap fill on the Mapping tab. Position your text (click on the picture once to see it and again to set it down). Then right-click and render.

A basic drop-shadow is created by clicking on Edit Shape, then Copy. The destination is the same layer. Click on Finish Edit. Nothing seems to happen because the duplicate text is directly on top of the original.

Click Edit Shape and drag the text down to the right. You don’t know if you’ve got the top or the bottom copy of the text, so click the Move Edit Object To Back button (under Copy) to place it beneath the other.

On the Colour tab pick flat shading style and ensure that black is selected in the palette window. Hit Finish Edit. You’ll see coloured text with a solid black drop-shadow. Now you can make the shadow more realistic. Click Edit Shape and, if foreground text is selected, click Next to move to the shadow.

Go to the Effects tab and click on Darken. Move the slider down to about 30 per cent and click Finish Edit to check out the effect. Better – you can see the background now – but the look can be further improved by feathering the edges. Selecting the shadow for editing again, and on the Parameters tab set a Feather value. Try single-figure numbers at first.

By the way, there’s something to try while you have a bitmap file loaded. Select it for editing and drag the corner handles to distort the rectangle the bitmap occupies. The contents will warp to fit the new shape, so it’s easy to make an image appear to lie down, for example.

The darkening effect of the shadow only applies to objects on the same layer. If you move both text and shadow to a layer of their own, only the text remains visible.

This is a pity. Satori sadly lacks the ability to group objects, so if you want to move the text, you have to drag its shadow around separately. Had it been possible to make this effect on a layer dedicated to text, both could have been repositioned as a unit by selecting Move Layer in the layer tools.

One more text effect I’m going to quickly show you before moving on can be seen in the screen grab below. Here the shading within the characters gives the effect of rounded 3D shapes.

Enter some solid text on a blank canvas. Make a copy of the text directly on top of itself, but colour the top layer blue and set the feathering value to about five. The fuzzy edges enable the perimeter of the solid black text to show through. The blue blurring extends beyond it, though. You can clear this away by making a second copy if the solid text, this time send it to the mask layer. Invert the mask by pressing the appropriate button in the layer list. This makes the layer transparent outside the boundary of the text, hiding the halo.

A NEW BRUSH

Version 1.63 of Satori lacks the facility to define new brush types with textures of your own devising. You can, however, build new brushes which are modified version of the existing ones.

Suppose, for example, that the chalk isn’t quite to your taste. You’d like a painting tool just like it, but rougher in texture. It’s easily done. To try this you’ll need to have a blank canvas open.

Bring up the Brush Setup dialog through View, Brush Setup, Type, or by double-clicking in the black square in the paint tools which shows the current brush size. Click on the Type tab and then on the New button.

Enter a name of Coarse Chalk and move on to the Profile tab. Here you can set the solidity of the chalk tip across its diameter. You need a solid tip with a fairly distinct edge, so drag the middle handle as far up and to the left as it will go.

Incidentally, while you’re here, spend a minute playing around with this dialog. Pull the middle handle in a bit, so you can see all of the profile line. Click midway between two handles to make a new one. Drag it down and see what happens to the tip graphic – it’s firm at the edges and centre, but fainter in between.

Clearly, you can produce some strange tip shapes here. Reshape the curve to give the chalk tip and skip forward to the Styles tab. Click the Chalk check box to say that this is the texture you want Coarse Chalk to paint with, and wind the value up to 90 to increase the degree of chalkiness. Now press Apply Now and Save. Close the dialog.

The new texture has appeared as an extra button at the end of painting tools. Press it and, with a suitable size selected, draw on the canvas. Compare the result with the original chalk.

If you want to delete a painting tool, go back to the Brush Setup dialog. Highlight the tool’s name on the Library tab and hit Delete.

LIGHT AND DARK

We finish off this month’s tutorial with a closer look at the colour correction tools. I mentioned these in part one of the series (refer back to the January issue) but restricted myself to the controls on the Slider tab. These offer brightness and contrast sliders along with the means to shift the overall colour balance on three scales: cyan-red, magenta-green and yellow-blue.

These are all global in their effects – moving a slider changes every pixel in the image equally. But some pictures have problems that require more selective control. Load to file GAYST.TIF from the SuperCD. While not badly in need or correction, the wide range of light and shade make it an ideal test-bed.

On the Colour Correction dialog’s Curve tab is a tool which enables you to brighten or darken some parts of a picture more that others. You can home in on an existing range of light intensities to which most of the effects of your brightness corrections are confined.

Let’s say we want to give the darker areas of the street in the picture above a lift, without brightening the pale areas unduly. The graph runs from the darkest pixels on the left to the brightest on the right. If you drag a handle above or below the line, you’ll see the pixels with those light intensities get brighter or darker.

So, to brighten the darker areas, try pulling the second handle upwards to about 75 per cent. The shadowed areas get lighter, as do the bright areas, but not to the same extent. Even so, I’d like to further fine-tune the correction so that there is hardly any effect outside the shadow.

Press the Straight button to put the graph back as it was. Click on the line either side of the handle you just moved. New handles appear. If you drag the original handles again, the new ones act as anchors, preventing the curve from extending as far as it did before.

Unfortunately we’re now getting some strange colour shifts. We need to be more scientific about where additional handles are placed.

Go to the Colour window and click on the eye dropper tool. Sample the picture in the shaded part of the road. Switch to the values tab, where you will see the RGB values for the sampled colour. Every time you sample a colour you need to switch away from this tab and switch back again – the values are only updated when the tab display is refreshed.

Various samples in the shade will give values broadly in the range 40 to 70. The maximum allowable is 255, so roughly speaking the top end of the brightness levels we’re dealing with is a quarter of the way up the scale.

Go back to the Colour Correction dialog and pull the second handle down the line to a position as close as you can get it to 25 per cent. This will act as an anchor at the top level. Now add a handle midway between zero and 25 per cent. Pull it up a small amount at a time and watch the effects.

While large increases have an effect further up the scale, these dramatic changes are far beyond what’s needed. Smaller increases give a very noticeable improvement in the shadows, with only the tiniest change elsewhere.

That’s all we’re going to cover for now. Next month we will finish off this Satori series by concentrating on a painting exercise together many of the threads that we’ve covered over the last three months.

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