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<h1>The Save Window</h1>
<h2><a name="format-notes">Format Notes</a></h2>
<dl>
<dt><a name="gif"><img src="images/fig-179.gif" width="151"
height="16"></a></dt>
<dd>While <i>xv</i> can read both the GIF87a and GIF89a
variants of the GIF format, it will normally write
GIF87a. <i>xv</i> will only write a GIF89a file if there
are image comments to be saved (comment blocks being a
GIF89a extension).. This is in keeping with the GIF89
specification, which states that if you don't need any of
the features added in GIF89, you should continue to write
GIF87, for greater compatibility with old GIF87-only
readers. <p>Since GIF only supports one format (up to 8
bits per pixel, with a colormap), there will be no file
size difference between a <b>Full Color</b> and a <b>Greyscale</b>
image. A <b>B/W Dithered</b> image, on the other hand,
will be considerably smaller.</p>
<p>If you are currently in <b>24-bit mode</b> , and you
are saving in any color mode other than <b>B/W Dithered</b>
, the currently selected 24->8 conversion algorithm
will be used to generate an 8-bit version of the current
image, and that image will be written. (See "<a
href="control-window-3.html#bit-menu">The 24/8 Bit Menu</a>"
for more info.) </p>
</dd>
<dt><a name="jpeg"><img src="images/fig-180.gif" width="151"
height="16"></a></dt>
<dd>One minor clarification: 'JPEG' is an image compression
algorithm, <i>not</i> an image file format. 'JFIF' is a
file format created by the fine folks at the Independent
JPEG Group for the storage and interchange of 'JPEG'-ed
image data. As such, it is the de-facto standard for
'JPEG' images. So, technically, when folks talk about
'JPEG' files, what they probably mean is 'JFIF' files,
but it's not <i>necessarily</i> so. Therefore, it is
possible to run across 'JPEG' files that <i>xv</i> can't
read, because they don't adhere to the 'JFIF' file format
standard. Just thought you'd like to know. <p><b>Full
Color</b> images are written in a 24-bit RGB format, and <b>Greyscale</b>
images are written in an 8-bit greyscale format. <b>B/W
Dithered</b> images should <i>not</i> be used, as they
will probably wind up being larger than <b>Greyscale</b>
versions of the same images, due to the way JPEG works.
Note: You cannot write a <b>Reduced Color</b> JPEG file.
Trust me, given the method that JPEG uses to compress,
it's not in your best interest to save <b>Reduced Color</b>
JPEG files. If you attempt to do so, a <b>Full Color</b>
JPEG file will be saved. </p>
<p><a name="jpeg-dialog"><img src="images/fig-181.gif"
width="414" height="230"> </a></p>
<p>When you save in the JPEG format, the dialog box shown
above will pop up and ask you for a quality setting and a
smoothing value. '75%' is the default quality value, and
really, it's a fine choice. You shouldn't have to change
it under normal circumstances. The lower you set the
quality, the higher the compression ratio will be (i.e.,
the JPEG file will be smaller). Note that setting the
quality setting to '100%' will <i>not</i> result in
'lossless JPEG' (i.e., the original and the JPEG'd images
will <i>not</i> be exactly the same, just very close). </p>
<p>The smoothing value is used to 'blur' images before
saving them. It's often a good idea to blur GIF (and
other 8-bit color) images before saving them, as you'll
get better compression that way, and it also may
partially undo the dithering that been done to many 8-bit
images. On the downside, you'll also get somewhat blurred
images. Something you have to decide for yourself.</p>
<p>Note: The JPEG support in <i>xv</i> is optional. While
it is normally enabled, it is possible that it may not be
enabled on your system (due to problems compiling the
JPEG library, or something). If this is the case, you
won't have a <b>JPEG</b> selection in the <b>Format</b>
menu. Please feel free to complain to whomever built the
binary that you're using. </p>
</dd>
<dt><a name="tiff"><img src="images/fig-182.gif" width="151"
height="16"></a></dt>
<dd><b>Full Color</b> and <b>Reduced Color</b> images are
written in a 24-bit RGB format, and <b>Greyscale</b>
images are written in an 8-bit greyscale format. <b>B/W
Dithered</b> images are written in a 1-bit B/W format.<p><a
name="tiff-dialog"><img src="images/fig-183.gif"
width="294" height="190"> </a></p>
<p>When you save in the TIFF format, the dialog box shown
above will pop up and ask you which type of image
compression it should use. <b>None</b>, <b>LZW</b>, and <b>PackBits</b>
compression types are available for use with all the
Color modes. In addition, there are two <b>B/W Dithered</b>-only
algorithms, <b>CCITT Group3</b> and <b>CCITT Group4</b> .
</p>
<p>Note: The TIFF support in <i>xv</i> is optional. While
it is normally enabled, it is possible that it may not be
enabled on your system (due to problems compiling the
TIFF library, or something). If this is the case, you
won't have a <b>TIFF</b> selection in the <b>Format</b>
menu. Please feel free to complain to whomever built the
binary that you're using. </p>
</dd>
<dt><a name="postscript"><img src="images/fig-184.gif"
width="151" height="16"></a></dt>
<dd><b>Full Color</b> and <b>Reduced Color</b> images are
stored in a 24-bit RGB format, <b>Greyscale</b> images
are stored in an 8-bit greyscale format, and <b>B/W
Dithered</b> images are stored in a 1-bit B/W format. <p><i>xv</i>
writes Encapsulated PostScript, so you can incorporate <i>xv</i>-generated
PostScript into many desktop-publishing programs. <i>xv</i>
also prepends some color-to-greyscale code, so even if
your printer doesn't support color, you can still print
'color' PostScript images. These images will be three
times larger (in file size) than their greyscale
counterparts, so it's a good idea to save <b>Greyscale</b>
PostScript, unless you know you may be printing the file
on a color printer at some point.</p>
<p>Also, you should probably never need to generate <b>B/W
Dithered</b> PostScript, as every PostScript printer I've
ever heard of can print greyscale images. The only valid
cases I can think of are: A) doing it for a special
effect, and B) doing it to generate a much smaller
(roughly 1/8th the size) PostScript file.</p>
<p>Note: When you try to save a PostScript file, the <i>xv
postscript</i> window will pop up to let you specify how
you want the image printed. (See "<a
href="postscript-window.html">The PostScript Window</a>"
for details.) </p>
</dd>
<dt><a name="pbmraw"><img src="images/fig-185.gif"
width="151" height="16"></a></dt>
<dd><b>Full Color</b> images are saved in <b>PPM</b> format. <b>Greyscale</b>
images are saved in <b>PGM</b> format. <b>B/W Dithered</b>
images are saved in <b>PBM</b> format. Each of these
formats are tailored to the data that they save, so PPM
images are larger than PGM images, which are in turn
larger than PBM images. <p>In the <b>raw</b> variation of
the PBM formats, the header information is written in
plain ASCII text, and the image data is written as binary
data. This is the more popular of the two dialects of
PBM, as it produces considerably smaller image files. </p>
</dd>
<dt><img src="images/fig-186.gif" width="151" height="16"></dt>
<dd>Like <b>PBM/PPM (raw)</b>, only the image data is written
as ASCII text. As such, images written in this format
will be several times larger than images written in <b>PBM/PGM/PPM
(raw)</b>. This is a pretty good format for interchange
between systems because it is easy to parse. Also, since
they are pure, printable ASCII text, images saved in this
format can be mailed, without going through a <i>uuencode</i>-like
program. <p>Note that <i>xv</i>-created PBM files (both <b>raw
</b>and <b>ascii </b>variants) may break some PBM readers
that do not correctly parse comments. If your PBM reader
cannot parse comments, you can easily edit the PBM file
and remove the comment lines. A comment is everything
from a "#" character to the end of the line. </p>
</dd>
<dt><a name="xbm"><img src="images/fig-187.gif" width="151"
height="16"></a></dt>
<dd>Saves files in the format used by the <i>bitmap</i>
program, which is part of the standard X11 distribution.
Since bitmap files are inherently 1-bit per pixel, you
can only select the <b>B/W Dithered</b> option for this
format. </dd>
<dt> </dt>
<dt><a name="xpm"><img src="images/fig-188.gif" width="151"
height="16"></a></dt>
<dd>New to <i>xv </i>version 3.10, you can now load and save
images in the XPM (X PixMap) format. Such files are best
suited to small-ish images with a small number of colors,
such as multi-color icons, and the like. One nifty
feature of this format is that images can be created and
edited using a text editor. All color choices work as
expected. One warning: <i>xv</i> will not write out an
XPM file with more than 256 different colors. If you are
viewing a 24-bit image and save it as an XPM file, <i>xv</i>
will first compute an 8-bit version of the image using
the current 24->8 conversion algorithm (see "<a
href="control-window-3.html#bit-menu">The 24/8 Bit Menu</a>"),
and then save that. </dd>
<dt> </dt>
<dt><a name="bmp"><img src="images/fig-189.gif" width="151"
height="16"></a></dt>
<dd><i>xv</i> will write a number of different types of BMP
files depending on the 8/24 bit mode that you're in, the
number of colors in the image, and the current 'Colors'
choice. <p>If you are currently in <b>8-bit Mode</b>, and
you select <b>Full Color</b>, <b>Reduced Color,</b> or <b>Greyscale</b>,
<i>xv</i> will write out an uncompressed 4- or 8-bits per
pixel BMP file, based on the number of different colors
in the current image.</p>
<p>If you are in <b>24-bit Mode</b> and you select <b>Full
Color</b>, the program will write out an uncompressed
24-bits per pixel image.</p>
<p>If you are in <b>24-bit Mode</b> and you select <b>Greyscale</b>,
an uncompressed 8-bit per pixel BMP file will be written.</p>
<p>If you select <b>B/W Dither</b>, a 1-bit per pixel BMP
file will be written. </p>
</dd>
<dt><a name="rasterfile"><img src="images/fig-190.gif"
width="151" height="16"></a></dt>
<dd><b>Full Color</b> and <b>Reduced Color</b> images are
stored in a 24-bit RGB format, <b>Greyscale</b> images
are stored in an 8-bit greyscale format, and <b>B/W
Dithered</b> images are stored in a 1-bit B/W format. </dd>
<dt> </dt>
<dt><a name="sgi-rgb"><img src="images/fig-191.gif"
width="151" height="16"></a></dt>
<dd>If you select <b>Full Color</b> or <b>Reduced Color</b> ,
the program will write a 24-bit image. Otherwise, it will
write out an 8-bit image. </dd>
<dt> </dt>
<dt><a name="targa"><img src="images/fig-192.gif" width="151"
height="16"></a></dt>
<dd>Another new format added to <i>xv</i> version 3.10. <i>xv</i>
can now read and write 24-bit uncompressed Targa files.
As such files are about the only reason folks still use
the Targa format, this shouldn't be a problem. The color
choices will do what you'd expect, but given that <i>xv</i>
only reads/writes 24-bit Targa files, saving anything but
<b>Full Color</b> would be a waste. </dd>
<dt> </dt>
<dt><a name="fits"><img src="images/fig-193.gif" width="151"
height="16"></a></dt>
<dd>Saves images in the FITS format, a greyscale-only format
used primarily by astronomers. </dd>
<dt> </dt>
<dt><a name="pm"><img src="images/fig-194.gif" width="151"
height="16"></a></dt>
<dd>Note: This format is was developed at Penn, and is rarely
seen outside of Penn. If you don't know anything about
it, trust me, you don't want to. <p><b>Full Color</b>
images are saved in the 3-plane, 1-band, PM_C format. <b>Greyscale</b>
and <b>B/W Dithered</b> images are both saved in the
1-plane, 1-band, PM_C format. As such, there is no size
advantage to saving in the <b>B/W Dithered</b> format. </p>
</dd>
<dt><a name="filename-list"><img src="images/fig-195.gif"
width="151" height="16"></a></dt>
<dd>This is not an 'image file format' at all, which is why
it appears separate from the rest of the formats in the <b>Format
</b>menu. Instead of saving the current image, what this
does is save a list of all the filenames in the <i>xv </i>controls
window file list. This file list can be used in
conjunction with the '<tt>-flist</tt>' option. See "<a
href="modifying-behavior-3.html#miscellaneous-options">Modifying
xv Behavior</a>" for more details. </dd>
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