How to create a thumbnail image in NodeJs using sharp library?

Question

I am trying to find a suitable library for image processing,
Basically, I have a use-case for Resizing, Compressing and creating thumbnails of an image,
I found that sharp seems to be a popular node library choice for image processing,

I am able to do some basic operations like resizing an image but,
I couldn't find a way to create thumbnails or smaller sized quality images of the original one.
Can someone please point to the correct code for creating thumbnails and smaller resolution images using the sharp library?

Sample working code:

const sharp = require('sharp');

let test = async () => {

    await sharp('/pathToImage/test.jpg')
    .resize({
        fit: sharp.fit.outside
    })
    .sharpen()
    .toFile('fitOutside.jpg')
    .then(info => { 
        console.log(info);
    })
    .catch(err => {
        console.log(err);
    });

};

test();

Reference -
http://sharp.pixelplumbing.com/en/stable/api-resize/
https://sharp.pixelplumbing.com/en/stable/api-resize/#examples_2

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– Rob, Commented Aug 24, 2019 at 17:14
I don't understand your question. Just resize down to eg. 128 x 128 and save as a jpg. Isn't that a thumbnail? — jcupitt
– jcupitt, Commented Aug 26, 2019 at 4:45
I tried to resize by setting the desired dimensions but, it's removing a part of the image. I need a good quality small-sized version of the original HQ image — Dev1ce
– Dev1ce, Commented Aug 26, 2019 at 4:50

jcupitt · Accepted Answer · 2019-08-26 08:59:25Z

6

If you give both width and height, sharp will usually need to either add or remove pixels on one axis. You can control what it does with the fit parameter:

http://sharp.pixelplumbing.com/en/stable/api-resize/

The default is centre, it sounds like you'd prefer outside.

answered Aug 26, 2019 at 8:59

jcupitt

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5 Comments

Dev1ce Over a year ago

Updated the question, I just tried using fit: sharp.fit.outside without specifying the dimensions, but in this case, it kept the original size? Should I specify the width and height parameters?

jcupitt Over a year ago

You have two options: 1. Just give width and it'll resize to that width while letting height float. 2. Give width and height, and specify how you'd like the image to be fitted.

Dev1ce Over a year ago

For case -> 1. I specify the width and fit correct? and for case 2. I specify the width, height and fit: sharp.fit.outside

jcupitt Over a year ago

No, you only need fit if you give both width and height.

Dev1ce Over a year ago

then case 2. is correct yea? for case 1. only specify width?

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