Graphics Programs Reference
In-Depth Information
There is normally a 2 GB file size limit in older versions of Photo-
shop and most other computer applications. To respond to the
need for larger file sizes, Adobe launched the Large Document
Format (PSB). It supports documents up to 300,000 pixels in any
dimension (up to 100 inches at 300 ppi). All Photoshop features,
such as layers, effects, and filters, are supported.
Tip
Large Document Format
Doesn't Automatically Mean
Larger Files
When comparing a file saved as a
standard .psd file versus the large
format .psb file, the two file sizes
are virtually identical. Using the
Large Document Format does not
increase file size, it just allows a
larger-sized file to be saved.
Additionally, 32-bits-per-channel images can be saved as PSB files.
It's important to remember that files saved in the PSB format can
be opened only in newer versions of Photoshop.
PNG (.png)
Layers
8-bit
16-bit
32-bit
FORMATS THAT
SUPPORT ALPHA
CHANNELS
Bitmap
Grayscale
Duotone
Indexed Color
RGB
CMYK
Lab
Multichannel
Do you need embedded
transparency for use in print-
ing, multimedia, video, or
animation programs? Then
you might want to stick with
file formats that support
alpha channels. Be sure to
check your software pro-
gram's manual to see which
of the following formats are
compatible:
• Photoshop
• BMP
• JPEG2000
• Large Document Format
• Photoshop PDF
• Photoshop 2.0
• Photoshop Raw
• Pixar
• SGI RGB
• Targa
• TIFF
The Portable Network Graphics format provides lossless compres-
sion. It is increasingly common on the Internet, but not all brows-
ers support it. The PNG format was created to be a patent-free
alternative to GIF. Its major advantage is the PNG-24 file, which
allows for 24-bit images (8 bits per channel) and embedded trans-
parency. It is technically superior to GIF.
The file on the left is a PNG-24. Notice how the transparency is handled perfectly
(even in the soft glowing areas). On the right is a GIF, which is an 8-bit image.
Transparency is not handled as cleanly, and you will l l notice a white edge outside
of the glow.
