How to Resize Image Only If Width Exceeds with Graphics/Image Magick

How to resize image only if width exceeds with Graphics/Image Magick

You can easily achieve that by using an 'unlikely large' height value:

convert  orig.png  -resize '64x10000>'  scaled.png

This will resize the original PNG only if its width was larger than 64 pixels or if its height is larger than 10 000 pixels. But the chance that the command will ever encounter an input that's higher than 10 000 pixels is very low. So it will (almost) only encounter input files where the width value matches.

Original PNGs with widths lower than 64 pixels will remain untouched (unless their height is above 10 000 pixels...).

CollectionFS Graphicsmagick resize width only if larger than

This works:

gm(readStream, fileObj.name()).resize(1200, 1200, '>').quality(100).autoOrient().stream().pipe(writeStream);

However, after using it with the gridfs package you may get this error:
Error: <ID> does not exist. This is a package's bug, so this topic would go separately.

Bash: batch resize images if width/height exceeds a specific value

A possible solution:

#!/bin/sh

set -e
maxwidth="1900"  # in pixels, the widest image you want to allow.

#find all .jpg in current dir and subdirectories
FILES="$(find . -iname '*.jpg')"

for imagefile in $FILES
do
if [ -f "$imagefile" ]; then
imgwidth=`sips --getProperty pixelWidth "$imagefile" | awk '/pixelWidth/ {print $2}'`
else
    echo "Oops, "$imagefile" does not exist." 
    exit
fi

if [ $imgwidth -gt $maxwidth ]; then
    echo " - Image too big. Resizing..."
    sips --resampleWidth $maxwidth "$imagefile" > /dev/null 2>&1  # to hide sips' ugly output 
    imgwidth=`sips --getProperty pixelWidth "$imagefile" | awk '/pixelWidth/ {print $2}'`
    imgheight=`sips --getProperty pixelHeight "$imagefile" | awk '/pixelHeight/ {print $2}'`
    echo " - Resized "$imagefile" to $imgwidth""px wide by $imgheight""px tall";
fi
done

resizing image with rmagick/imagemagick to be less than a specified product of its width and height

You need to properly calculate the ratio, which is a square root from your desired dimension divided by (row multiplied by col):

row, col = [2793, 1970]
ratio = Math.sqrt(4_000_000.0 / (row * col))
[row, col].map &ratio.method(:*)
#⇒ [
#  [0] 2381.400006266842,
#  [1] 1679.6842149465374
#]
[row, col].map(&ratio.method(:*)).reduce(:*)
#∞ 3999999.9999999995

Resize images that are larger than X in Ubuntu

You might want to use ImageMagick. It isn't included in the default installations of Ubuntu and many other Linux distributions, so you will have to install it first. Use the following command:

sudo apt-get install imagemagick

You can specify a width (or height) and ImageMagick will resize the image for you while preserving the aspect ratio.

The following command will resize an image to a width of 2000:

convert example.png -resize 2000 example.png

There is also an option so that it will only shrink images to fit into the given size. It won't enlarge images that are smaller. This is the '>' resize option. Think of it only applying the resize to images 'greater than' the given size, the syntax might be a little counter-intuitive.

convert example.png -resize 2000\>  example.png

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You can use bash to apply the command to all of your images,

for file in *.png; do convert $file -resize 2000\> $file; done

Increase the length of first image in graphics magick

Your problem with the resize is caused by mixing .in() methods which insert things direct on the command line with the graphicsmagic library methods which apply some extra heuristics on what to do. Adding a .resize attempts to resize the main graphic object (which is then ignored by .mosaic which sizes the final image according to the contents).

The easiest solution is to use your .in()-based syntax for the resize:

    gm()
    .in('-page', '+0+0')
    .in('-resize', '50x100!')
    .in('http://localhost:8080/user1')
    .in('-page', '+50+0')
    .in('http://localhost:8080/user2')
    .in('-page', '+50+50')
    .in('http://localhost:8080/user3')
    .mosaic()
    .write('C:/images/output1.jpg', function (err) {
        if (err) console.log(err);
    });

This works on my test with local images.

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