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 -f 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. You can use MxN to specify a rectangular bounding box.
The image is shrunk so that it just fits within this area, images
which are smaller than this are expanded.

.TP
.B -f FORMAT, --format=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. If 
.B FORMAT
is a relative path, the name of the input directory is prepended. In other
words, any path in
.B FORMAT
is relative to the directory of the current input file.

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[Q=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 -c, --crop
Crop the output image down. The image is shrunk so as to completely fill the
bounding box in both axies, then any excess is cropped off. 

.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. Error can mean one or more
conversions failed.

.SH SEE ALSO
vipsheader(1)