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jimp-dev / jimp

An image processing library written entirely in JavaScript for Node, with zero external or native dependencies.
http://jimp-dev.github.io/jimp/
MIT License
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Some images have 0 hash. #338

Open yaneony opened 7 years ago

yaneony commented 7 years ago

Found this issue https://github.com/oliver-moran/jimp/issues/67 which was closed, but...

I still get some images with 0 hash. For example this one. 908018

Getting "1000000000000000000000000000000000000000000000000000000000000000" hash on it.

I was trying to replace pHash.js but without success.

Ojas-Gulati commented 7 years ago

What is your code/offending line?

yaneony commented 7 years ago

What do you mean?

teramotodaiki commented 4 years ago

I have same problem. I don't know why but you can reproduce it in Codesandbox below. https://codesandbox.io/s/loving-ride-eiljq?file=/src/index.js

In short, the distance between two different images will be zero. Jimp.distance(image1, image2) === 0

These are sample images. You can download:

image1 image1 image2 image2

rambonette commented 1 year ago

@teramotodaiki did you manage to find a workaround for this issue?

I'm experiencing the same issue with two completely different .png images, still the hash() function is returning the same "80000000000" hash.

I tried converting the two images to .jpg but obtained the same results.

Jimp.read('l3qn22kjlm.png', (err, res) => { console.log(res.hash())} );
Jimp.read('lcjb3u6c27.png', (err, res) => { console.log(res.hash())} );

//output
80000000000
80000000000

I'm currently using jimp package without any issues except for this one, so I'm guessing it has something to do with these specific images:

l3qn22kjlm

lcjb3u6c27

Thanks in advance to all the kind souls willing to help :)

hipstersmoothie commented 1 year ago

If anyone wants to submit a PR to fix I'm able to review and merge!

chrisj42 commented 10 months ago

So I really don't know what I'm doing when it comes to phash algorithms, but I have been having this issue and was rather annoyed at it since it basically could not handle sketches at all properly.

I took a look at the phash.js file though and read some of the comments, and something in the getHash function caught my eye. It says that it skips over the first value because it can heavily throw off the average... however the iteration doesn't skip anything. So, I decided to have the x,y start at 1,1 and reduce the average division to match, and suddenly this issue has completely disappeared. I tested all the above images too and they all now produce reasonable outputs.

Am I missing something or was that the issue..? I can make a PR if that's desired, I haven't because I honestly have no idea what the algo is doing and I just made a dumb edit following one of the comments.