libvips/man/vipsthumbnail.1

.TH VIPSTHUMBNAIL 1 "13 May 2010"
.SH NAME
vipsthumbnail \- make thumbnails of image files
.SH SYNOPSIS
.B vipsthumbnail [flags] imagefile1 imagefile2 ...
.SH DESCRIPTION
.B vipsthumbnail(1)
processes each 
.B imagefile
in turn, shrinking each image to fit within a 128 by 128 pixel square.
The shrunk image is written to a new file named
.B tn_imagefile.jpg.
This program is typically faster and uses less memory than
other image thumbnail programs.

For example:

 $ vipsthumbnail fred.png jim.tif

will read image files 
.B fred.png
and 
.B jim.tif
and write thumbnails to the files
.B tn_fred.jpg
and
.B tn_jim.jpg.

 $ vipsthumbnail --size=64 -o thumbnails/%s.png fred.jpg

will read image file
.B fred.jpg
and write a 64 x 64 pixel thumbnail to the file 
.B thumbnails/fred.png.

.SH OPTIONS
.TP
.B -s N, --size=N
Set the output thumbnail size to 
.B N 
x 
.B N 
pixels. The image is shrunk so that it just fits within this area, Images
which are smaller than this are expanded.

.TP
.B -o FORMAT, --output=FORMAT     
Set the output format string. The input filename has any file type suffix
removed, then that value is substitued into 
.B FORMAT
replacing
.B %s.
The default value is
.B tn_%s.jpg
meaning JPEG output, with
.B tn_
prepended. You can add format options too, for example
.B tn_%s.jpg:20
will write JPEG images with Q set to 20.

.TP
.B -p I, --interpolator=I               
Resample with interpolator 
.B I.
Use 
.B vips --list classes
to see a list of valid interpolators. The default is 
.B bilinear.

.TP
.B -r, --sharpen=none|mild|MASKFILE
Images can look a little soft after shrinking.  This option lets you specify
a sharpening mask. Use "none" to disable sharpening, or "mild" to sharpen
lightly, or give the filename of a custom mask file to use. The default is
"mild".  The built-in mild sharpen mask is:

 3 3 24 0
 -1 -1 -1
 -1 32 -1
 -1 -1 -1

.TP
.B -e PROFILE, --eprofile=PROFILE        
Export thumbnails with this ICC profile. Images are only colour-transformed if
there is both an output and an input profile available. The input profile can
either be embedded in the input image or supplied with the
.B --iprofile
option.

.TP
.B -i PROFILE, --iprofile=PROFILE        
Import images with this ICC profile, if no profile is embdedded in the image. 
Images are only colour-transformed if
there is both an output and an input profile available. The output profile
should be supplied with the
.B --oprofile
option.

.TP
.B -d, --delete
Delete the output profile from the image. This can save a small amount of
space. 

.TP
.B -v, --verbose
.B vipsthumbnail(1)
normally runs silently, except for warning and error messages. This option
makes it print a list of the operations it performs on each image.

.SH RETURN VALUE
returns 0 on success and non-zero on error.
.SH SEE ALSO
header(1)