Graphics Programs Reference
In-Depth Information
Image brushes
Art, pattern, and scatter brushes have been supercharged. Finally you can use
embedded raster artwork in the brushes you create, and you can mix raster with
vector in the same brush. You'll find several examples of raster brush art in this
chapter, but keep in mind the following points when creating brushes from raster
artwork:
•
Limit the size
(in pixels) for pattern and art brushes to approximately one megapixel
(see Tip “
How big is a megapixel
”), though scatter brushes can be any size, although
performance can slow down. Because the brush's redraw performance lags with
larger brushes, Illustrator will offer to “optimize” (down sample) any single raster
object (the copy it uses, not the original) that exceeds that limit. Illustrator can't
downsample multiple objects, and may not be able to downsample very large images,
either. You'll see a warning to resize the artwork before creating the brush, at which
point you can choose Object> Rasterize to downsample your image. Illustrator
downsamples the image to match the size of the image on the artboard at the
resolution you choose in the dialog. It may be enough simply to scale the image
before rasterizing, or it might also require rasterizing at a lower resolution,
depending upon the size you're starting with.
How big is a megapixel?
A megapixel is roughly one million pixels. Multiply W × H in pixels to get the total
area. A filled rectangle 1024 × 1024 px is the maximum usable size, but can
sometimes be larger if the artwork boundaries contains fully transparent pixels.
•
To maintain the quality
of your artwork, create the brush as close to the size you need
as possible. Brushes from raster artwork are pixel based, not vector, even if they
include vector in them, and will degrade if significantly scaled. To ensure that you
can access the original artwork, or to re-rasterize it at another resolution, it's best to
always rasterize a copy of your object.
•
Distortion affects rasters,
and if you bend pixels along a path, as is common with art
brushes, the artwork has to be interpolated. Some distortion can be too extreme for
Illustrator to fill in the gaps. There's a significant difference between choosing
Stretch to Fit and Scale Proportionally with art brushes, so experiment to get the
results you want when working with images in your brushes.
•
With a pattern brush
, if your art isn't oriented properly to the path, you must rotate it
first on the artboard. You should note that although you can change the orientation
of your artwork in the Art Brush Options dialog, Illustrator doesn't always rotate
large or complex raster art correctly. To avoid difficulty, rotate the artwork on the
art-board before attempting to create the brush.
•
Raster portions of brushes
can't be colorized. Changing the Colorization settings in the
Brush Options dialog won't have any effect on the raster portions of your brush, only
vector elements (see Sharon Steuer's “shell” gallery later in this section for an
example of this).
Edit automatic corner tiles
When you drag a brush from the Brushes panel onto the artboard, the artwork is
expanded into a group of vectors, each tile within its own sub-group. Some of the
expanded tiles contain an outer unfilled/unstroked bounding rectangle. In order for
an edited tile to correctly replace an original, you must retain the size of the tile
you're replacing, including (if it has one) its bounding rectangle.
Embedded images for brushes
In order to make a linked image into a raster brush, click Embed in your Control
panel.
