convert jpeg to size suitable for printing the image on an A4 with lpr

[Emanuel Berg <embe8573@student.uu.se>]

I wrote this zsh wrapper to `convert' to do it.

With the 72 PPI resolution, the image get smaller!

With the 200 PPI resolution, the image gets bigger,
and it looks good when viewed with feh, but when
I print (with lpr) the increased-size image gets split
up in two parts on the paper with a black rectangular
box (?) showing up as well.

do-a4-pic () {
    local pic=$1
    local name=${pic:r}
    local ext=${pic:e}
    local new=${name}-a4.${ext}
    local res=1654x2339 # 200 PPI; 595x842 for 72 PPI - http://www.a4papersize.org
    convert $pic \
            -resize $res \
            -gravity center \
            -background white \
            -extent $res \
            $new
}

This is the image I try to print in "A4 size":

    http://user.it.uu.se/~embe8573/bike/shimano-b.jpg

This image is the result of the above computation and
doesn't look good when printed:

    http://user.it.uu.se/~embe8573/bike/shimano-b-a4.jpg

-- 
underground experts united
http://user.it.uu.se/~embe8573