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Computer Science, Information Theory

Comparing Lossy Compression Methods for Differentially Private Mechanisms

Comparing Lossy Compression Methods for Differentially Private Mechanisms

Imagine you have a big box full of images, and you want to share them with someone else. However, the images are too large to send directly, so you need to find a way to compress them first. Compression methods are like magic tricks that make the images smaller without losing their quality. But which method is best? In this article, we’ll explore some common compression techniques used in distributed image representation and evaluate their effectiveness.
Logit Values and Log-Likelihood Estimators

One approach to compressing images is to use logit values. Think of logit values as a special kind of cookie that helps the classifier figure out which features are important for recognizing an image. The classifier can then use these features to make predictions, even if some parts of the image are missing. This method works well when both parties have the same features (like dimensions) and can share them with each other.
But what happens when one party’s embedding is compressed losslessly (i.e., 32 bits per dimension), while the other party’s embedding is compressed in a lossy manner? This is like having two different kinds of cookies – one that stays fresh for a long time, and another that gets stale quickly. The classifier can still recognize the image using the fresh cookie, but it might not be able to do so as accurately with the stale one.
Effectiveness of Compression Methods

So, how effective are these compression methods at preserving the accuracy of the classifier? To find out, we compared them with a method called Neural Distributed Image Compression (NDIC). NDIC models the common information between two parties and compresses it separately for each party. This is like having two different recipes for making cookies – one for each party. The result is that both parties have their own special cookies that they can use to make predictions about images together.
We found that NDIC performs better than other methods when the parties have different dimensions or when one party’s embedding is compressed losslessly. This is like having two different types of cookies with different lifespans – the fresh cookie stays good for longer, but the stale cookie might still work for a while.
Conclusion
In conclusion, choosing the right compression method depends on the specific situation. When both parties have the same features and can share them directly, logit values can be used to make accurate predictions. However, when the dimensions are different or one party’s embedding is compressed losslessly, NDIC performs better. Think of it like having two different kinds of cookies – one that stays fresh for a long time, and another that gets stale quickly. The right cookie depends on the situation!