Dave,
The following bash script seems to work. There are 3 cases you need
to consider. If the aspect ratio is greater than 180/130, if the
aspect ratio is less than 180/130 but greater than or equal to 1, if
the aspect ratio is less than 1.
#!/bin/bash
infile="your_infile"
outfile="your_outfile"
dwidth=180 # desired thumbnail width
dheight=130 #desired thumbnail height
width=`identify -format "%w" $infile` # actual image width
height=`identify -format "%h" $infile` # actual image height
aspect=`echo "scale=5; $width / $height" | bc` # actual image aspect
ratio
daspect=`echo "scale=5; $dwidth / $dheight" | bc` # desired
thumbnail aspect ratio
test1=`echo "$aspect > $daspect" | bc` # returns 1 if true and 0 if false
test2=`echo "$aspect >= 1" | bc` # returns 1 if true and 0 if false
if [ $test1 -eq 1 ]
then
echo "aspect larger than desired aspect (wider than tall)"
resize="${dheight}x${dheight}^"
elif [ $test2 -eq 1 ]
then
echo "aspect less than desired aspect (wider than tall) but
greater than 1"
resize="${dwidth}x${dwidth}"
else
echo "aspect less than 1 (taller than wide)"
resize="${dwidth}x${dwidth}^"
fi
convert $infile -resize $resize +repage \
-gravity Center -crop ${dwidth}x${dheight}+0+0 +repage $outfile
Note the use of the ^ in cases 1 and 3
Note: I have not checked this yet for the case where your desired
width is less than your desired height (e.g. 130x180 for example).
This may require an alternate version.
I will try to make a proper script of this for any desired aspect
ratio over the next few days and add it to my script page.
Fred
Hehe, that was a little confusing, sorry. So you're saying do
something like this:
convert 1.jpg -filter Lanczos -resize 180x130^ -gravity center
1_.jpg but it wont work for square images.
Dave
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