Review: Alpha Paint
NOTICE: This is the originally submitted text for an article that appeared
in issue #138 of MICROTIMES magazine. (There are some slight edited
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Copyright(C)1995 Douglas J. Nakakihara.
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Alpha Paint: 36-bit Butter for your Toast
By Douglas J. Nakakihara
If you really need professional results, I've always thought that it was
better to paint in RGB and then hope and pray it looked OK on a composite
monitor. Well, after using AlphaPaint from InnoVision Technology, I can
now see that the problem was in my tools, not in the display capability.
Alpha Paint lets you paint right on the Toaster's Program monitor, so it's
WYSIWYG in the purest sense.
Alpha Channel
With 24-bit real-time painting capabilities, an 8-bit graphics alpha
channel, and a 4-bit dithered video alpha channel, Alpha Paint is billed as
a "36-bit" paint program. Actually, Alpha Paint implements several
different alpha channel tools. There are brush graphics and video alpha
channels, a weight (density) control, and a stencil alpha channel.
Generally, graphics alpha channels are used to composite graphics together,
like when you stamp a brush down with some level of transparency over a
full-screen image. Video alpha channels allow video to show through
graphics. So parts of an image may appe ar solid when viewed as a graphic;
however, when keyed over video, defined areas will appear transparent,
letting you see the underlying video.
The brush alpha channels affect the pen or brush you are painting with and
allow you to independently control their graphics and video transparency.
Weight control is a global density setting and directs the overall amount
of "paint" that is applied. The stencil alpha channel is a protection
mechanism that masks out defined areas of the screen.
The Magic Wand tool lets you quickly define a stencil alpha channel.
Using a definable tolerance range, this tool will unprotect (unmask) areas
of the screen. This works best when the desired object is against a fairly
solid-color background. Depending on the situation, this feature may
eliminate the need to trace an object by hand.
Hyper-Palette
Alpha Paint's palette has 200 "Color Boxes" displayed in selectable banks
of 20. In addition to merely defining a solid color, a Color Box can also
define a "spread pattern" (see below). This allows you to quickly fill
objects with gradients and other patterns as well as define alpha channels.
As you would expect, you can copy between Color Boxes, swap contents, and
create a spread between two Boxes. Individual colors can be defined using
either RGB or HSV (Hue, Saturation, and Value) values. There is also a
24-bit hue and saturation color wheel called a "Color Cube" and a Value
slider available to visually fix a color.
Spread 'Em
The right side of the Palette menu is devoted to custom "spreads."
Essentially this is a color range creation tool, but goes beyond the usual
implementation. As you add colors to the "Spread Preview Bar", a gradient
is formed based on where you place the colors on the bar. A color can be
repositioned by simply dragging its position indicator, and there is an
option to evenly space all colors. Color order can be globally rotated or
inverted. Individual colors can be deleted or duplicated as well. Spreads
can be linear, circular, or radial. Plus, you can adjust the Z-axis
rotation of linear and radial spreads.
Drawing Tools
The basic drawing tools like line, curve, rectangle, circle, ellipse,
polygon, free-hand shape, fill, text, airbrush, etc. are present and
accounted for. The cutting tool is used in conjunction with any of the
geometric shape drawing tools (i.e., circle, polygon, etc.).
Magnification is fixed at 75, 100, 200, 400, and 800 percent of normal.
In the Pen menu, you can choose between circle, oval, and rectangle for
your pen shape. Besides just allowing you to adjust the pen size, you can
also adjust its width and even rotate it. (Obviously, the later doesn't do
much if your pen shape is a circle .) Adjustable feathering is available to
give brush strokes a soft professional-looking edge. The Fade setting
allows you to define how the applied pen or brush will gradually increase
or decrease in one continuous stroke.
Fill 'Er Up
The common Fill tool has some interesting nuances in Alpha Paint. Not only
can you fill an area with a brush, but you have the option of automatically
scaling it to fit the area or having it warped to fill the area. A
tolerance level can be set to determine how close to the original color a
pixel can be when Alpha Paint calculates the fill area.
Text
Alpha Paint supports Toaster, Chroma, and Postscript fonts. Adjustable
attributes include height, width, italics, character spacing, Z-axis
rotation, line spacing, and line justification. With Postscript fonts, you
have the option of wrapping the text around a circle. Once the text has
been defined, you can then apply brush attributes, like rotation, shadows,
etc.
Brushing Up
Brushes can be loaded (and saved) from the Brush menu in addition to being
cut-out from the main screen. When loading a brush you have the options of
trimming black pixels (RGB 0,0,0) from the edges and adjusting the aspect
ratio for (square pixel) brushes created on the Macintosh. From this menu
you also set the global brush graphics and video alpha channels.
You may also size and rotate a brush. The parameters for both of these
attributes may be set manually or interactively. When rotating a brush,
besides allowing you to position and rotate in the X, Y, and Z dimensions,
you can also set the focal length. This allows you to set the visual depth
of field making the brush appear flat or elongated along the Z-axis.
Brushes can be given a beveled edge, outlined, and extruded. There are
also provisions for shadows, as well as back-lit glow and neon-outline
effects, all with adjustable parameters. As an alternative to a brush's
original colors, you can change them to any of the Color Boxes or even map
a new image on it. Edges have the option of being feathered. You may set
independent graphics and video visibility parameters, which are used in
conjunction with the brush alpha channel settings. Most of these brush
attributes are equally applicable to when you are drawing with a pen or
adding text.
The brush tools are also used for compositing full-screen images using
alpha channels. For example, by selecting a left-to-right
greyscale-gradient Color Box for the graphics alpha channel, a full-screen
brush can be stamped down and fade in horizontally over a colored
background.
Drawing Modes
In addition to a normal drawing mode there is Rub Thru, Erase, Hue,
Colorize, Negative, Smear, Watercolor, Mix, Lighten, Darken, Smooth,
Sharpen, Gamma, Contrast, and Oil Paint. Rub Thru lets you paint the swap
screen image into the main screen. The Erase mode replaces pixels with the
current background color. Hue replaces the color hue of a pixel with the
that of the current Color Box. Colorize replaces the hue and saturation
and can be used to colorize greyscale images. The Negative mode reverses
the RGB value of pixels.
The Smear mode smudges areas of an image. Watercolor paints with the
current Color Box, but blends-in existing pixels. Mix is similar but uses
an existing color in the image instead of the Color Box. Smooth can be
used to blur the edges of an object while Sharpen enhances edges. Gamma
and Contrast adjust the difference between light and dark colors. The Oil
Paint mode applies an "impressionist painting style" that mimics oil
painting.
To make using things like Rub Thru a little easier, there is an "Onion
Skin" option. This allows the swap screen to show thru at 25-percent
visibility.
TV O.D.'d
The TV Controls Menu includes standard image correction parameters like
gamma, contrast, brightness, color, sharpness, tint, red, green, and blue.
Additionally, there are special effect operators like embossing, negative,
posterize, mosaic, and oil paint. Embossing adds an engraved look to an
image. Posterize reduces the number of colors yielding a "blown-up"
poster-like effect. Mosaic pixelizes the picture into squares. Negative
and Oil Paint work as described previously for Drawing modes.
I Do I Don't
If you're like me and love to try many things out before committing (OK,
some people call these mistakes.), you'll be glad to know that Alpha Paint
features multiple undo and redo, limited only by your RAM. Moreover, redo
is taken one step further with Redo+. This will re-perform the last
drawing operation using the existing paint attributes. So let's say you
just painstakingly outlined an object by hand, but you forgot you wanted a
feathered border. Well just undo your first attempt, adjust the feathering
setting, and hit Redo+. This can save you so much time when you're trying
to tweak something to get "just" the right effect.
Where appropriate, Alpha Paint features preview windows that give you a
rough idea of what the results of your settings will be. Definitely a
time-saver and something we're seeing more and more of in newer
applications.
File Formats
Alpha Paint can save images in Framestore, IFF24, and JPEG formats.
Brushes can be saved in IFF24 only. Alpha Paint can load these formats,
plus rendered Toaster/Montage CG pages and all IFF images, except low-res
HAM6. (Note: Montage is InnoVision's Toaster CG product.)
Graphics on Video
The Play Menu combines some basic functions of the Toaster Switcher and
Alpha Paint graphics. Generally this will be used to overlay graphics on
video; however, you can also overlay video on video with an alpha channel
mask. For transitions, a fixed-speed fade and cut are provided.
Little Big Things
There are so many little things in Alpha Paint designed to save time and
make your life easier. For example, if you want a brush automatically
pasted down in the center of the screen, just press the Return key. The
Clear-to tool lets you quickly clear the screen to any color/pattern in the
palette. Often after you've adjusted a bunch of settings for a certain
effect, you may want to clear out all settings and start fresh for the next
one. Just hit the F1 key and everything is reset to the default settings,
but the image is left untouched.
System Requirements
Alpha Paint requires Video Toaster 2.0 or greater, 12MB Fast RAM, 1MB Chip
RAM, 10MB hard drive space, a 68030 CPU or better, and AmigaDOS 1.3+.
Alpha Paint does some serious calculations and you'll want all of the
horsepower you can get! The program also supports Wacom and CalComp
pressure sensitive drawing tablets.
Comments and Criticisms
Alpha Paint really needs ARexx support. Besides just being able to batch
process images, it would allow you to animate some of the effects. It
would also be nice if all option parameters could be set using the mouse,
instead of only some. This would minimize having to move your hand back
and forth between the mouse and keyboard. The mini-sliders introduced in
LightWave 3.5 would be perfect.
Another limitation is that you cannot multitask out of Alpha Paint and do
something else. It basically takes over the whole machine. (I am told,
however, that this was a necessary evil to get Alpha Paint to perform its
magic.)
I also wish that the controls interface optionally or simultaneously
appeared on the Amiga RGB monitor. Some Toaster users (like me) have their
Toaster monitors off to the side. As such, they may not be located in a
position where it is comfortable to do detailed work. Interestingly, you
can faintly see the interface on the Amiga RGB monitor if you turn the
brightness up on your monitor.
Conclusion
Alpha Paint is one heck of a program. It comes with a thick three-ring
notebook manual with many tutorials to have you up and running in no time.
You'll soon be able to literally whip up a beautiful complex video graphic
in just minutes.
I'll be the first to admit that you could duplicate everything that Alpha
Paint does using other programs you probably already have. However, Alpha
Paint puts it all there right in front of you. Right at your finger tips.
All wrapped up in one straight-forward easy-to-use package. If you make
your living with the Toaster, you need this program. It's priced a bit
higher than other Amiga paint programs, but it will save you time and
quickly pay for itself.
AlphaPaint
$699.95 (Available direct for $399 for a limited time)
InnoVision Technology
1933 Davis Street, Ste 238
San Leandro, CA 94577
(510) 638-0800