Resize images

gistfile1.txt

#!/bin/bash

set -eu

error() {
    local msg="$1"

    echo $msg >&2
    exit 1
}

abspath() {
    local path="$1"

    # Check path is not empty
    [ -z "$path" ] && error "Path is empty"

    # Check path exist's
    [ -e "$path" ] || error "Path doesn't exit: $path"

    # Check path is a directory
    [ -d "$path" ] || error "Path is not a directory: $path"

    cd "$path"
    pwd -P
}

resize() {
    local file="$1" size="$2" path="$3"

    mogrify \
        -path "$path" \
        -filter Triangle \
        -define filter:support=2 \
        -thumbnail "$size" \
        -unsharp 0.25x0.08+8.3+0.045 \
        -dither None \
        -posterize 136 \
        -quality 82 \
        -define jpeg:fancy-upsampling=off \
        -define png:compression-filter=5 \
        -define png:compression-level=9 \
        -define png:compression-strategy=1 \
        -define png:exclude-chunk=all \
        -interlace none \
        -colorspace sRGB \
        "$file"
}

SRC_PATH=$(abspath "${1:-}")
DST_PATH=$(abspath "${2:-}")
MAX_SIZE=${3:-}

# Check binaries
which magick &>/dev/null || error "You need to install ImageMagick"
which mogrify &>/dev/null || error "You need to install ImageMagick"

# Check source and destionation is not the same
[ "$SRC_PATH" != "$DST_PATH" ] || error "Source and dest. path can't be the same"

# Check we set max size or use default
[ -z "$MAX_SIZE" ] && MAX_SIZE="1000"

# Find all the images
for file in $(find "$SRC_PATH" -type f -name *.jpg); do

    # Create the destination directory
    dir=$(dirname $file)
    dst_dir=$DST_PATH${dir##$SRC_PATH}
    mkdir -p $dst_dir

    # Get the size in pixels
    size=$(magick identify -format "%w:%h" "$file")
    width=${size%%:*}
    height=${size##*:}

    # Check if this is already correct size
    # or if it's portrait or landscape
    if [ "$width" -lt "$MAX_SIZE" -a "$height" -lt "$MAX_SIZE" ]; then
        echo "SKIP: $file ($width x $height)"
        cp -f "$file" "$dst_dir"
    elif [ "$width" -gt "$height" ]; then
        echo "$file ($width x $height portrait)"
        resize "$file" "$MAX_SIZE" "$dst_dir"
    else
        echo "$file ($width x $height landscape)"
        resize "$file" "x$MAX_SIZE" "$dst_dir"
    fi
done

The command takes 3 arguments. ./script.sh [src] [dst] [size]

It will then resize any image that is larger then that size either vertically of horizontally. If you don't specify a size then it will default to 1000 pixels.

If the file is already smaller then it will simply copy it over since it's already smaller then then size we want.

So I downloaded a few pictures from unsplash and created a structure.

$ tree img/
img/
├── test1
│   ├── alicia-petresc-ttjZ2LAbwDs-unsplash.jpg
│   └── angela-bailey-qgYDMG4hU3w-unsplash.jpg
└── test2
    ├── marcelo-cidrack-TvquR9Ye_i4-unsplash.jpg
    └── test3
        ├── cameron-venti-Z8uJ_8PkNpg-unsplash.jpg
        ├── edward-howell-cvVDDgyU-ps-unsplash.jpg
        ├── nathan-dumlao-YLL-mI9OZAg-unsplash.jpg
        └── randy-fath-2o3tAN2Xh-s-unsplash.jpg

Then I downloaded and ran the script.

$ curl https://gist.githubusercontent.com/mickep76/ca6d067b561b29cf923817fff6cfa384/raw/ac49a86a5385bdc3a1bcc12aa8b2e0eed41f9b16/gistfile1.txt >resize.sh
$ chmod +x ./resize.sh
$ mkdir img2
$ ./resize.sh img img2 2000

Then it will resize all pictures to 2000 if they are larger then that horizontally or vertically and we end up with an identical structure in the destionation.

$ tree img2/
img2/
├── test1
│   ├── alicia-petresc-ttjZ2LAbwDs-unsplash.jpg
│   └── angela-bailey-qgYDMG4hU3w-unsplash.jpg
└── test2
    ├── marcelo-cidrack-TvquR9Ye_i4-unsplash.jpg
    └── test3
        ├── cameron-venti-Z8uJ_8PkNpg-unsplash.jpg
        ├── edward-howell-cvVDDgyU-ps-unsplash.jpg
        ├── nathan-dumlao-YLL-mI9OZAg-unsplash.jpg
        └── randy-fath-2o3tAN2Xh-s-unsplash.jpg

3 directories, 7 files

I ran this on Mac OS X using Bash.

So the behaviour you're getting is by design, that it would skip a file of size 400x400 since it's already smaller then the default size of 1000 pixels.

If you want to modify it to always resize just modify the following.

    # Check if this is already correct size
    # or if it's portrait or landscape
#    if [ "$width" -lt "$MAX_SIZE" -a "$height" -lt "$MAX_SIZE" ]; then
#        echo "SKIP: $file ($width x $height)"
#        cp -f "$file" "$dst_dir"
    if [ "$width" -gt "$height" ]; then
        echo "$file ($width x $height portrait)"
        resize "$file" "$MAX_SIZE" "$dst_dir"
    else
        echo "$file ($width x $height landscape)"
        resize "$file" "x$MAX_SIZE" "$dst_dir"
    fi

Thanks for the detailed reply.