Show HN: JavaScript image compressor | Hacker News Reader

Show HN: JavaScript image compressor

github.com

41 pointschenfengyuan11 comments

I was really hoping this would implement some complex algorithm or at least be an interesting implementation, however, it seems to just divide the image height/width by the aspect ratio:

https://github.com/xkeshi/image-compressor/blob/master/src/i...

As I understand it, this library draws the image into a Canvas to then re-compress the Canvas' via the Browser's native `toDataURL('image/jpeg', quality);`. You can optionally specify a width/height to downscale the image.

Imho the readme needs to state what the library actually does. E.g.

"This takes a user image from a file input, optionally resizes it, and returns a JPEG, PNG or WebP as a Blob, ready to upload."

Agreed! I haven't looked into this at all but I wonder if you can run some algorithm on the datauri.

This is a simple resize using canvas.drawImage(). Since data is permanently lost in the output file, it is misleading to call it compression.

Lossy compression is still technically compression.

I've optimally compressed your image for you:

<EOF>

(For very naive definitions of "optimal")

This could be a great (although not really real-world) addition to a JS benchmark suite.

Input (original)

name: Fuckscape_d80352_5915762.jpg

type: image/jpeg

size: 19.14 KB

Output (compressed)

name: Fuckscape_d80352_5915762.jpg

type: image/jpeg

size: 20.64 KB (-7.85% off)

So your image-compressor actually adds 7.85% to the filesize? Maybe I don't understand the meaning of compression, but shouldn't it be smaller?

you should share an image link plus your settings/script to make this useful for OP

I got better results:

Input (original) name: the-northern-trifid-nebula-8499-1920x1200.jpg type: image/jpeg size: 737.26 KB

Output (compressed) name: the-northern-trifid-nebula-8499-1920x1200.jpg type: image/jpeg size: 263.17 KB (64.30% off)

I guess your original was more optimised than mine.

A tool like this should definitely check to make sure it has actually reduced the file size and, if not, just return the original with a note that it couldn't make any gains.

The result is dependent on your Browser. This library uses the Browser's native `ctx.toDataURL('image/jpeg', quality)` method to re-encode the image. The actual compression algorithm is not implemented in JavaScript.

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