ImageMagick - how to enforce min/max heights/widths?

Question

Using ImageMagick, how can I resize an image to have a minimum:

• height of 150px
• width of 200px

and also have a maximum:

• height of 225px
• width of 275px

UPDATE:

In case it helps, here's a further explanation of what I'm experiencing.

I have a buch of images with all different ratio dimensions. Some images have 1:5 height/width ratios. Some have 5:1 height/width ratios. So that I want to do is set that a minimum height/width size for the image but also don't want the image size to be larger than a particular size.

If I need to apply white padding to an image to make it fit within my constraint so that I don't have to distort the image, I'd like to do so.

Answer 1

I can't entirely get my head around your requirement, but I think this should be possible if you run IM twice.

See the manual on geometry options:

A combination of

widthxheight> Change as per widthxheight but only if an image dimension exceeds a specified dimension.

and

widthxheight^ Minimum values of width and height given, aspect ratio preserved.

might do the trick. However, for images whose aspect ratio lies outside your requirements, I think you will have to create a fixed size canvas in IM, fill it with some colour, insert the image, and do a trim() on it... Probably not possible in one go, though.

Answer 2

OK, I do some similar processing. I don't have a generic solution for arbitrary sizes and aspect ratios, but if your input set of images is either 1:5 or 5:1, you can group them into 2 categories and process accordingly using some of these code snippets.

Step 1: determine which aspect ratio the image is, and based on that, set your target final altered dimensions.

INPATH="path/to/your_file.jpg"
DIMS=`identify "${INPATH}" | awk '{print $3}'`
WIDTH=`echo "${DIMS}"| cut -dx -f1`
HEIGHT=`echo "${DIMS}"| cut -dx -f2`
if [[ ${WIDTH} > ${HEIGHT} ]]
then
    #file is in landscape orientation
    THUMBDIM="80x60"
    WEBDIM="624x480"
else
    #file is in portrait orientation
    echo -n "(Portrait orientation) "
    THUMBDIM="60x80"
    WEBDIM="480x624"
fi

Step 2, do the actual resize:

convert "${INPATH}" -resize "${THUMBDIM}" "resized-${INPATH}"

This sample assumes a fixed set of desired sizes, but of course you could do some basic arithmetic using your original dimensions as input and scaling up in proportion to fit within your stated boundaries.