HashAlgorithm.ComputeHash

Question

I have 2 same images with different Image properties and file properties (e.g. CreationDate, etc.). When I calculate hash, I get different hashes. Is there any way to skip such properties and calculate hash to get same hashes?

Awaiting help. Thanks

Added one edge case that may or may not matter to your application. — Eric J.
– Eric J., Commented Mar 9, 2016 at 1:34

Community · Accepted Answer · 2017-05-23 12:15:30Z

5

You can read the image data into a byte array and hash that byte array.

That way, differences in meta-data would not be considered.

Since the 2D data is read into a 1D array, you can construct cases where two images with different dimensions have the same hash. For example, consider a 2x2 image and a 4x1 image. R means red and B means blue (just to pick two colors)

RB
BR

and

RBBR

Both would have the same hash code. If that matters to you, prepend (or append) the width and height of the image to the byte array before hashing.

edited May 23, 2017 at 12:15

CommunityBot

11 silver badge

answered Mar 9, 2016 at 1:08

Eric J.

151k65 gold badges353 silver badges563 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Kishan Over a year ago

Thank you! Is there any solution for video formats?

Eric J. Over a year ago

There's a lot more data involved, but the same basic approach. You could probably grab a few seconds of data from the middle of the video and use that if performance is key. I would not grab the beginning or end as some videos have the same lead-in (e.g. if the same company made them)

Collectives™ on Stack Overflow

HashAlgorithm.ComputeHash

1 Answer 1

2 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related