convert2jpg

#!/bin/bash
######################################################################
# Author: jrjbear@gmail.com
# Date: Wed Feb  5 20:19:47 2014
# File: convert2jpg
#
# Usage: convert2jpg [-Sq] [-s N] [-w N] [-c S] image
# Description: A helper script tool wrapping NetPBM utilities
######################################################################

# Set up the defaults
width=1
colour='-color grey'
quiet=""
standardise=' | pnmtojpeg ${quiet}'
commands=""

function print_usage()
{
    echo "Usage: $0 [-Sq] [-s N] [-w N] [-c S] image" >&2
    echo "Convert images of different types (gif, tiff...) into jpeg" >&2
    echo "-S: Enhance the image and make it sharper" >&2
    echo "-s: Scale the image to \`N'" >&2
    echo "-w: Add a border to the image with width=\`N'" >&2
    echo "-c: Add a border to the image with colour=\`S'" >&2 
    echo "-q: Suppress diagnostic message" >&2
    echo "Note that the order of enhance/scale/border options will be" >&2
    echo "used as the order to do the corresponding operations" >&2
}

# Mock functions for NetPBM utilities. Note that we use global
# variable `quiet' to avoid parsing the arguments temporarily
# $1 is the input filename (empty means stdin)
# $2 is the output string
# $3 is the diagnostic message
function _netpbm_mock_func()
{
    cat $1
    echo "$2"
    if [[ -z "${quiet}" ]]; then
        echo "$3" >&2
    fi
}

function pnmnlfilt()
{ 
    _netpbm_mock_func "" "${FUNCNAME} $*" \
        "Enhance the image using parameters: $*" 
}

function pnmscale()
{
    _netpbm_mock_func "" "${FUNCNAME} $*" \
        "Scale the image using parameters: $*" 
}

function pnmmargin()
{
    _netpbm_mock_func "" "${FUNCNAME} $*" \
        "Add margin to image using parameters: $*" 
}

function giftopnm()
{ 
    local file="$1"
    if [[ -n "${quiet}" ]]; then
        file="$2"
    fi
    _netpbm_mock_func "${file}" "${FUNCNAME} $*" \
        "Convert gif file to pnm file"
}

function tgatoppm()
{
    local file="$1"
    if [[ -n "${quiet}" ]]; then
        file="$2"
    fi
    _netpbm_mock_func "${file}" "${FUNCNAME} $*" \
        "Convert tga file to ppm file"
}

function xpmtoppm()
{
    local file="$1"
    if [[ -n "${quiet}" ]]; then
        file="$2"
    fi
    _netpbm_mock_func "${file}" "${FUNCNAME} $*" \
        "Convert xpm file to ppm file"
}

function pcxtoppm()
{
    local file="$1"
    if [[ -n "${quiet}" ]]; then
        file="$2"
    fi
    _netpbm_mock_func "${file}" "${FUNCNAME} $*" \
        "Convert pcx file to ppm file"
}

function tifftopnm()
{
    local file="$1"
    if [[ -n "${quiet}" ]]; then
        file="$2"
    fi
    _netpbm_mock_func "${file}" "${FUNCNAME} $*" \
        "Convert tiff file to pnm file"
}

function jpegtopnm()
{
    local file="$1"
    if [[ -n "${quiet}" ]]; then
        file="$2"
    fi
    _netpbm_mock_func "${file}" "${FUNCNAME} $*" \
        "Convert jpeg file to pnm file"
}

function pnmtojpeg()
{ 
    _netpbm_mock_func "" "${FUNCNAME} $*" \
        "Convert pnm file to jpeg file" 
}


while getopts ":Sqs:w:c:" opt; do
    case $opt in
        S ) sharpness=' | pnmnlfilt -0.7 0.45 ${quiet}'
            commands="${commands}${sharpness}" ;;
        s ) size=$OPTARG
            scale=' | pnmscale -xysize ${size} ${size} ${quiet}'
            commands="${commands}${scale}" ;;
        w ) width=$OPTARG
            if [[ -z "${border}" ]]; then
                border=' | pnmmargin ${colour} ${width} ${quiet}' 
                commands="${commands}${border}" 
            fi ;;
        c ) colour="-color ${OPTARG}"
            if [[ -z "${border}" ]]; then
                border=' | pnmmargin ${colour} ${width} ${quiet}' 
                commands="${commands}${border}" 
            fi ;;
        q ) quiet='-quiet' ;;
        \?) print_usage
            exit 1 ;;
    esac
done
shift $(($OPTIND-1))

for filename in "$@"; do
    case "${filename}" in
        *.gif ) convert='giftopnm' ;;
        *.tga ) convert='tgatoppm' ;;
        *.xpm ) convert='xpmtoppm' ;;
        *.pcx ) convert='pcxtoppm' ;;
        *.tif ) convert='tifftopnm' ;;
        *.jpg ) convert='jpegtopnm' ;;
            * ) echo "$0: Unknown filetype '${filename##*.}'" >&2
                exit 1;;
    esac
    
    convert="${convert}"' ${quiet}'
    outfile="${filename%.*}.new.jpg"
    eval "${convert}" "${filename}" "${commands}" "${standardise}" > "${outfile}"
done