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. 

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. 

Use "xN" or "Mx" to just resize on
one axis. 

Append "<" to only resize if the input image is smaller than the
target, append ">" to only resize if the input image is larger than the target.

.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. 
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 -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 axes, 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 -t, --rotate
Auto-rotate images using EXIF orientation tags. 

.TP
.B -a, --linear
Shrink images in linear light colour space. This can be much slower. 

.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)